'97 Grand fuel pump relay killed fuel pump?
 

I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
(well ... maybe one problem with a myriad of 'solutions'). I finally
replaced the computer and the problems stopped for a couple of months. This
week the engine died a couple of times while driving in hot weather and then
would start again after a few minutes. It then began not starting when
driven and then parked for about a half hour. It finally would not start
again. No codes, no engine light. Towed to mechanic.

He says the fuel pump and the fuel pump relay are bad. It was replaced last
year. The mechanic says the relay may have burnt out the fuel pump over time
by creating spikes and low voltage. I don't know much about the system, but
that sounds very strange for relays. Is this a likely diagnosis?

Thanks,

Joe M

Re: '97 Grand fuel pump relay killed fuel pump?
 

I can tell you my fuel pump took out it's relay, it wouldn't stop
running the pump with the ignition off. It ran another couple of months with
a new relay and replaced culprit clogged filter. As a test it should run for
a couple of seconds every time you turn on the ignition key on then shut
off, if the engine is not started. But this really sounds like the
Crankshaft Position Sensor:
http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's why
I asked you to test for the sound of fuel to confirm it's really not
running.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/


"Joe_M" <x24w0cg02@NOsneakSPAMemail.com> wrote in message
news:EvWki.5849$rR.1016@newsread2.news.pas.earthli nk.net...
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months.
This
> week the engine died a couple of times while driving in hot weather and
then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced
last
> year. The mechanic says the relay may have burnt out the fuel pump over
time
> by creating spikes and low voltage. I don't know much about the system,
but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>



--
Posted via a free Usenet account from http://www.teranews.com

Re: '97 Grand fuel pump relay killed fuel pump?
 

I can tell you my fuel pump took out it's relay, it wouldn't stop
running the pump with the ignition off. It ran another couple of months with
a new relay and replaced culprit clogged filter. As a test it should run for
a couple of seconds every time you turn on the ignition key on then shut
off, if the engine is not started. But this really sounds like the
Crankshaft Position Sensor:
http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's why
I asked you to test for the sound of fuel to confirm it's really not
running.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/


"Joe_M" <x24w0cg02@NOsneakSPAMemail.com> wrote in message
news:EvWki.5849$rR.1016@newsread2.news.pas.earthli nk.net...
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months.
This
> week the engine died a couple of times while driving in hot weather and
then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced
last
> year. The mechanic says the relay may have burnt out the fuel pump over
time
> by creating spikes and low voltage. I don't know much about the system,
but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>



--
Posted via a free Usenet account from http://www.teranews.com

Re: '97 Grand fuel pump relay killed fuel pump?
 

I can tell you my fuel pump took out it's relay, it wouldn't stop
running the pump with the ignition off. It ran another couple of months with
a new relay and replaced culprit clogged filter. As a test it should run for
a couple of seconds every time you turn on the ignition key on then shut
off, if the engine is not started. But this really sounds like the
Crankshaft Position Sensor:
http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's why
I asked you to test for the sound of fuel to confirm it's really not
running.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/


"Joe_M" <x24w0cg02@NOsneakSPAMemail.com> wrote in message
news:EvWki.5849$rR.1016@newsread2.news.pas.earthli nk.net...
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months.
This
> week the engine died a couple of times while driving in hot weather and
then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced
last
> year. The mechanic says the relay may have burnt out the fuel pump over
time
> by creating spikes and low voltage. I don't know much about the system,
but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>



--
Posted via a free Usenet account from http://www.teranews.com

Re: '97 Grand fuel pump relay killed fuel pump?
 

I can tell you my fuel pump took out it's relay, it wouldn't stop
running the pump with the ignition off. It ran another couple of months with
a new relay and replaced culprit clogged filter. As a test it should run for
a couple of seconds every time you turn on the ignition key on then shut
off, if the engine is not started. But this really sounds like the
Crankshaft Position Sensor:
http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's why
I asked you to test for the sound of fuel to confirm it's really not
running.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/


"Joe_M" <x24w0cg02@NOsneakSPAMemail.com> wrote in message
news:EvWki.5849$rR.1016@newsread2.news.pas.earthli nk.net...
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months.
This
> week the engine died a couple of times while driving in hot weather and
then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced
last
> year. The mechanic says the relay may have burnt out the fuel pump over
time
> by creating spikes and low voltage. I don't know much about the system,
but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>



--
Posted via a free Usenet account from http://www.teranews.com

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>
You are still describing a code 12 issue I think.....

I would be making 'really' sure the body of the vehicle had full power.

To do this, I take a multimeter and read the volts at the battery posts
with the engine running and the headlights and heater fan and wipers on.
I then move the negative meter probe to the body with the positive
still on the battery positive and compare the voltages.

If the voltages are different, your body ground path is bad.

Good luck!

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>
You are still describing a code 12 issue I think.....

I would be making 'really' sure the body of the vehicle had full power.

To do this, I take a multimeter and read the volts at the battery posts
with the engine running and the headlights and heater fan and wipers on.
I then move the negative meter probe to the body with the positive
still on the battery positive and compare the voltages.

If the voltages are different, your body ground path is bad.

Good luck!

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>
You are still describing a code 12 issue I think.....

I would be making 'really' sure the body of the vehicle had full power.

To do this, I take a multimeter and read the volts at the battery posts
with the engine running and the headlights and heater fan and wipers on.
I then move the negative meter probe to the body with the positive
still on the battery positive and compare the voltages.

If the voltages are different, your body ground path is bad.

Good luck!

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?
>
> Thanks,
>
> Joe M
>
>
You are still describing a code 12 issue I think.....

I would be making 'really' sure the body of the vehicle had full power.

To do this, I take a multimeter and read the volts at the battery posts
with the engine running and the headlights and heater fan and wipers on.
I then move the negative meter probe to the body with the positive
still on the battery positive and compare the voltages.

If the voltages are different, your body ground path is bad.

Good luck!

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Thanks Bill,

Already replaced the crank position sensor when previously chasing P0351
codes. Did not seem to have any impact, but I hear it often accounts for
strange problems.

"L.W. (Bill) ------ III" <LWBill------@------.net> wrote in message
news:46944946$0$16366$88260bb3@free.teranews.com.. .
> I can tell you my fuel pump took out it's relay, it wouldn't stop
> running the pump with the ignition off. It ran another couple of months
> with
> a new relay and replaced culprit clogged filter. As a test it should run
> for
> a couple of seconds every time you turn on the ignition key on then shut
> off, if the engine is not started. But this really sounds like the
> Crankshaft Position Sensor:
> http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's
> why
> I asked you to test for the sound of fuel to confirm it's really not
> running.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Thanks Bill,

Already replaced the crank position sensor when previously chasing P0351
codes. Did not seem to have any impact, but I hear it often accounts for
strange problems.

"L.W. (Bill) ------ III" <LWBill------@------.net> wrote in message
news:46944946$0$16366$88260bb3@free.teranews.com.. .
> I can tell you my fuel pump took out it's relay, it wouldn't stop
> running the pump with the ignition off. It ran another couple of months
> with
> a new relay and replaced culprit clogged filter. As a test it should run
> for
> a couple of seconds every time you turn on the ignition key on then shut
> off, if the engine is not started. But this really sounds like the
> Crankshaft Position Sensor:
> http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's
> why
> I asked you to test for the sound of fuel to confirm it's really not
> running.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Thanks Bill,

Already replaced the crank position sensor when previously chasing P0351
codes. Did not seem to have any impact, but I hear it often accounts for
strange problems.

"L.W. (Bill) ------ III" <LWBill------@------.net> wrote in message
news:46944946$0$16366$88260bb3@free.teranews.com.. .
> I can tell you my fuel pump took out it's relay, it wouldn't stop
> running the pump with the ignition off. It ran another couple of months
> with
> a new relay and replaced culprit clogged filter. As a test it should run
> for
> a couple of seconds every time you turn on the ignition key on then shut
> off, if the engine is not started. But this really sounds like the
> Crankshaft Position Sensor:
> http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's
> why
> I asked you to test for the sound of fuel to confirm it's really not
> running.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Thanks Bill,

Already replaced the crank position sensor when previously chasing P0351
codes. Did not seem to have any impact, but I hear it often accounts for
strange problems.

"L.W. (Bill) ------ III" <LWBill------@------.net> wrote in message
news:46944946$0$16366$88260bb3@free.teranews.com.. .
> I can tell you my fuel pump took out it's relay, it wouldn't stop
> running the pump with the ignition off. It ran another couple of months
> with
> a new relay and replaced culprit clogged filter. As a test it should run
> for
> a couple of seconds every time you turn on the ignition key on then shut
> off, if the engine is not started. But this really sounds like the
> Crankshaft Position Sensor:
> http://jeep.off-road.com/jeep/articl....jsp?id=257990 That's
> why
> I asked you to test for the sound of fuel to confirm it's really not
> running.
> God Bless America, Bill O|||||||O
> mailto:-------------------- http://www.----------.com/
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Mike,

No codes on OBD II. I get codes 12 and 55 on the odometer and have for
months. I was told previously that code 12 always shows and is not an
indicator of a problem, even though it does not disappear after many start
cycles. Was I told wrong?

I had cleaned and reseated both the negative to body ground and the negative
to engine ground before the latest problem. I have not run the specific test
you mention. I will when I next get access to the car.

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>
> You are still describing a code 12 issue I think.....
>
> I would be making 'really' sure the body of the vehicle had full power.
>
> To do this, I take a multimeter and read the volts at the battery posts
> with the engine running and the headlights and heater fan and wipers on. I
> then move the negative meter probe to the body with the positive still on
> the battery positive and compare the voltages.
>
> If the voltages are different, your body ground path is bad.
>
> Good luck!
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Mike,

No codes on OBD II. I get codes 12 and 55 on the odometer and have for
months. I was told previously that code 12 always shows and is not an
indicator of a problem, even though it does not disappear after many start
cycles. Was I told wrong?

I had cleaned and reseated both the negative to body ground and the negative
to engine ground before the latest problem. I have not run the specific test
you mention. I will when I next get access to the car.

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>
> You are still describing a code 12 issue I think.....
>
> I would be making 'really' sure the body of the vehicle had full power.
>
> To do this, I take a multimeter and read the volts at the battery posts
> with the engine running and the headlights and heater fan and wipers on. I
> then move the negative meter probe to the body with the positive still on
> the battery positive and compare the voltages.
>
> If the voltages are different, your body ground path is bad.
>
> Good luck!
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Mike,

No codes on OBD II. I get codes 12 and 55 on the odometer and have for
months. I was told previously that code 12 always shows and is not an
indicator of a problem, even though it does not disappear after many start
cycles. Was I told wrong?

I had cleaned and reseated both the negative to body ground and the negative
to engine ground before the latest problem. I have not run the specific test
you mention. I will when I next get access to the car.

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>
> You are still describing a code 12 issue I think.....
>
> I would be making 'really' sure the body of the vehicle had full power.
>
> To do this, I take a multimeter and read the volts at the battery posts
> with the engine running and the headlights and heater fan and wipers on. I
> then move the negative meter probe to the body with the positive still on
> the battery positive and compare the voltages.
>
> If the voltages are different, your body ground path is bad.
>
> Good luck!
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Mike,

No codes on OBD II. I get codes 12 and 55 on the odometer and have for
months. I was told previously that code 12 always shows and is not an
indicator of a problem, even though it does not disappear after many start
cycles. Was I told wrong?

I had cleaned and reseated both the negative to body ground and the negative
to engine ground before the latest problem. I have not run the specific test
you mention. I will when I next get access to the car.

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>
> You are still describing a code 12 issue I think.....
>
> I would be making 'really' sure the body of the vehicle had full power.
>
> To do this, I take a multimeter and read the volts at the battery posts
> with the engine running and the headlights and heater fan and wipers on. I
> then move the negative meter probe to the body with the positive still on
> the battery positive and compare the voltages.
>
> If the voltages are different, your body ground path is bad.
>
> Good luck!
>
> Mike
> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
> Canadian Off Road Trips Photos: Non members can still view!
> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
> (More Off Road album links at bottom of the view page)

Re: '97 Grand fuel pump relay killed fuel pump?
 

Sometimes the cables can rot inside the clamps which is why the meter
test is a good one just to make sure.

It wouldn't hurt to meter the engine block with the volt test also.

Code 55 should be the only one.

Mike

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many start
> cycles. Was I told wrong?
>
> I had cleaned and reseated both the negative to body ground and the negative
> to engine ground before the latest problem. I have not run the specific test
> you mention. I will when I next get access to the car.
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>> You are still describing a code 12 issue I think.....
>>
>> I would be making 'really' sure the body of the vehicle had full power.
>>
>> To do this, I take a multimeter and read the volts at the battery posts
>> with the engine running and the headlights and heater fan and wipers on. I
>> then move the negative meter probe to the body with the positive still on
>> the battery positive and compare the voltages.
>>
>> If the voltages are different, your body ground path is bad.
>>
>> Good luck!
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Sometimes the cables can rot inside the clamps which is why the meter
test is a good one just to make sure.

It wouldn't hurt to meter the engine block with the volt test also.

Code 55 should be the only one.

Mike

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many start
> cycles. Was I told wrong?
>
> I had cleaned and reseated both the negative to body ground and the negative
> to engine ground before the latest problem. I have not run the specific test
> you mention. I will when I next get access to the car.
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>> You are still describing a code 12 issue I think.....
>>
>> I would be making 'really' sure the body of the vehicle had full power.
>>
>> To do this, I take a multimeter and read the volts at the battery posts
>> with the engine running and the headlights and heater fan and wipers on. I
>> then move the negative meter probe to the body with the positive still on
>> the battery positive and compare the voltages.
>>
>> If the voltages are different, your body ground path is bad.
>>
>> Good luck!
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Sometimes the cables can rot inside the clamps which is why the meter
test is a good one just to make sure.

It wouldn't hurt to meter the engine block with the volt test also.

Code 55 should be the only one.

Mike

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many start
> cycles. Was I told wrong?
>
> I had cleaned and reseated both the negative to body ground and the negative
> to engine ground before the latest problem. I have not run the specific test
> you mention. I will when I next get access to the car.
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>> You are still describing a code 12 issue I think.....
>>
>> I would be making 'really' sure the body of the vehicle had full power.
>>
>> To do this, I take a multimeter and read the volts at the battery posts
>> with the engine running and the headlights and heater fan and wipers on. I
>> then move the negative meter probe to the body with the positive still on
>> the battery positive and compare the voltages.
>>
>> If the voltages are different, your body ground path is bad.
>>
>> Good luck!
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Sometimes the cables can rot inside the clamps which is why the meter
test is a good one just to make sure.

It wouldn't hurt to meter the engine block with the volt test also.

Code 55 should be the only one.

Mike

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many start
> cycles. Was I told wrong?
>
> I had cleaned and reseated both the negative to body ground and the negative
> to engine ground before the latest problem. I have not run the specific test
> you mention. I will when I next get access to the car.
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4694d725$0$10412$9a6e19ea@unlimited.newshosti ng.com...
>> You are still describing a code 12 issue I think.....
>>
>> I would be making 'really' sure the body of the vehicle had full power.
>>
>> To do this, I take a multimeter and read the volts at the battery posts
>> with the engine running and the headlights and heater fan and wipers on. I
>> then move the negative meter probe to the body with the positive still on
>> the battery positive and compare the voltages.
>>
>> If the voltages are different, your body ground path is bad.
>>
>> Good luck!
>>
>> Mike
>> 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
>> 88 Cherokee 235 BFG AT's - Gone to the rust pile...
>> Canadian Off Road Trips Photos: Non members can still view!
>> Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
>> (More Off Road album links at bottom of the view page)
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many
> start cycles. Was I told wrong?

Fifty start cycles or scantool to reset.

Code 12 is only of consequence when it is surrounded by many other codes
from all over the place. In that case it means the battery cable, terminal,
or something inside the battery is not making good contact.

In my case the terminal popped off the battery when I was removing the
positive cable to clean the connection. :/

--
DougW

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many
> start cycles. Was I told wrong?

Fifty start cycles or scantool to reset.

Code 12 is only of consequence when it is surrounded by many other codes
from all over the place. In that case it means the battery cable, terminal,
or something inside the battery is not making good contact.

In my case the terminal popped off the battery when I was removing the
positive cable to clean the connection. :/

--
DougW

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many
> start cycles. Was I told wrong?

Fifty start cycles or scantool to reset.

Code 12 is only of consequence when it is surrounded by many other codes
from all over the place. In that case it means the battery cable, terminal,
or something inside the battery is not making good contact.

In my case the terminal popped off the battery when I was removing the
positive cable to clean the connection. :/

--
DougW

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M wrote:
> Mike,
>
> No codes on OBD II. I get codes 12 and 55 on the odometer and have for
> months. I was told previously that code 12 always shows and is not an
> indicator of a problem, even though it does not disappear after many
> start cycles. Was I told wrong?

Fifty start cycles or scantool to reset.

Code 12 is only of consequence when it is surrounded by many other codes
from all over the place. In that case it means the battery cable, terminal,
or something inside the battery is not making good contact.

In my case the terminal popped off the battery when I was removing the
positive cable to clean the connection. :/

--
DougW

Re: '97 Grand fuel pump relay killed fuel pump?
 

Grand back with new fuel pump and running.

I checked voltages with digital meter while engine idling with lights on,
wipers on, and heater fan on. The reading was just over 13.5 volts across
the battery terminals. About 2 to 4 hundredths of a volt higher with
negative taken from bolt attaching coolant overflow reservoir to body. About
3 to 5 hundredths higher with negative taken where the coil attaches to the
engine. I expect that a bad ground would create a much higher difference,
but I don't know how big a difference it would be. I don't think most
mechanics are going to be checking for differences measured in hundredths of
volts.

I still get code 12. The battery had been disconnected in the shop. My OBD
reader can reset OBD codes, but not the 12 code. Does it reset after 50
start cycles? Does start cycle mean starting the engine and then stopping it
without any requirement to let if run for a while or get to closed loop?

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
> Sometimes the cables can rot inside the clamps which is why the meter test
> is a good one just to make sure.
>
> It wouldn't hurt to meter the engine block with the volt test also.
>
> Code 55 should be the only one.
>
> Mike

Re: '97 Grand fuel pump relay killed fuel pump?
 

Grand back with new fuel pump and running.

I checked voltages with digital meter while engine idling with lights on,
wipers on, and heater fan on. The reading was just over 13.5 volts across
the battery terminals. About 2 to 4 hundredths of a volt higher with
negative taken from bolt attaching coolant overflow reservoir to body. About
3 to 5 hundredths higher with negative taken where the coil attaches to the
engine. I expect that a bad ground would create a much higher difference,
but I don't know how big a difference it would be. I don't think most
mechanics are going to be checking for differences measured in hundredths of
volts.

I still get code 12. The battery had been disconnected in the shop. My OBD
reader can reset OBD codes, but not the 12 code. Does it reset after 50
start cycles? Does start cycle mean starting the engine and then stopping it
without any requirement to let if run for a while or get to closed loop?

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
> Sometimes the cables can rot inside the clamps which is why the meter test
> is a good one just to make sure.
>
> It wouldn't hurt to meter the engine block with the volt test also.
>
> Code 55 should be the only one.
>
> Mike

Re: '97 Grand fuel pump relay killed fuel pump?
 

Grand back with new fuel pump and running.

I checked voltages with digital meter while engine idling with lights on,
wipers on, and heater fan on. The reading was just over 13.5 volts across
the battery terminals. About 2 to 4 hundredths of a volt higher with
negative taken from bolt attaching coolant overflow reservoir to body. About
3 to 5 hundredths higher with negative taken where the coil attaches to the
engine. I expect that a bad ground would create a much higher difference,
but I don't know how big a difference it would be. I don't think most
mechanics are going to be checking for differences measured in hundredths of
volts.

I still get code 12. The battery had been disconnected in the shop. My OBD
reader can reset OBD codes, but not the 12 code. Does it reset after 50
start cycles? Does start cycle mean starting the engine and then stopping it
without any requirement to let if run for a while or get to closed loop?

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
> Sometimes the cables can rot inside the clamps which is why the meter test
> is a good one just to make sure.
>
> It wouldn't hurt to meter the engine block with the volt test also.
>
> Code 55 should be the only one.
>
> Mike

Re: '97 Grand fuel pump relay killed fuel pump?
 

Grand back with new fuel pump and running.

I checked voltages with digital meter while engine idling with lights on,
wipers on, and heater fan on. The reading was just over 13.5 volts across
the battery terminals. About 2 to 4 hundredths of a volt higher with
negative taken from bolt attaching coolant overflow reservoir to body. About
3 to 5 hundredths higher with negative taken where the coil attaches to the
engine. I expect that a bad ground would create a much higher difference,
but I don't know how big a difference it would be. I don't think most
mechanics are going to be checking for differences measured in hundredths of
volts.

I still get code 12. The battery had been disconnected in the shop. My OBD
reader can reset OBD codes, but not the 12 code. Does it reset after 50
start cycles? Does start cycle mean starting the engine and then stopping it
without any requirement to let if run for a while or get to closed loop?

Thanks,

Joe M

"Mike Romain" <romainm@sympatico.ca> wrote in message
news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
> Sometimes the cables can rot inside the clamps which is why the meter test
> is a good one just to make sure.
>
> It wouldn't hurt to meter the engine block with the volt test also.
>
> Code 55 should be the only one.
>
> Mike

Re: '97 Grand fuel pump relay killed fuel pump?
 

Those volt readings are within any tolerances, when you start to see
tenths, you have issues.

Could have just been a bad pump, it happens.

I believe the code will reset with a key start count like it counts to
give you codes.

Mike

Joe_M wrote:
> Grand back with new fuel pump and running.
>
> I checked voltages with digital meter while engine idling with lights on,
> wipers on, and heater fan on. The reading was just over 13.5 volts across
> the battery terminals. About 2 to 4 hundredths of a volt higher with
> negative taken from bolt attaching coolant overflow reservoir to body. About
> 3 to 5 hundredths higher with negative taken where the coil attaches to the
> engine. I expect that a bad ground would create a much higher difference,
> but I don't know how big a difference it would be. I don't think most
> mechanics are going to be checking for differences measured in hundredths of
> volts.
>
> I still get code 12. The battery had been disconnected in the shop. My OBD
> reader can reset OBD codes, but not the 12 code. Does it reset after 50
> start cycles? Does start cycle mean starting the engine and then stopping it
> without any requirement to let if run for a while or get to closed loop?
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
>> Sometimes the cables can rot inside the clamps which is why the meter test
>> is a good one just to make sure.
>>
>> It wouldn't hurt to meter the engine block with the volt test also.
>>
>> Code 55 should be the only one.
>>
>> Mike
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Those volt readings are within any tolerances, when you start to see
tenths, you have issues.

Could have just been a bad pump, it happens.

I believe the code will reset with a key start count like it counts to
give you codes.

Mike

Joe_M wrote:
> Grand back with new fuel pump and running.
>
> I checked voltages with digital meter while engine idling with lights on,
> wipers on, and heater fan on. The reading was just over 13.5 volts across
> the battery terminals. About 2 to 4 hundredths of a volt higher with
> negative taken from bolt attaching coolant overflow reservoir to body. About
> 3 to 5 hundredths higher with negative taken where the coil attaches to the
> engine. I expect that a bad ground would create a much higher difference,
> but I don't know how big a difference it would be. I don't think most
> mechanics are going to be checking for differences measured in hundredths of
> volts.
>
> I still get code 12. The battery had been disconnected in the shop. My OBD
> reader can reset OBD codes, but not the 12 code. Does it reset after 50
> start cycles? Does start cycle mean starting the engine and then stopping it
> without any requirement to let if run for a while or get to closed loop?
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
>> Sometimes the cables can rot inside the clamps which is why the meter test
>> is a good one just to make sure.
>>
>> It wouldn't hurt to meter the engine block with the volt test also.
>>
>> Code 55 should be the only one.
>>
>> Mike
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Those volt readings are within any tolerances, when you start to see
tenths, you have issues.

Could have just been a bad pump, it happens.

I believe the code will reset with a key start count like it counts to
give you codes.

Mike

Joe_M wrote:
> Grand back with new fuel pump and running.
>
> I checked voltages with digital meter while engine idling with lights on,
> wipers on, and heater fan on. The reading was just over 13.5 volts across
> the battery terminals. About 2 to 4 hundredths of a volt higher with
> negative taken from bolt attaching coolant overflow reservoir to body. About
> 3 to 5 hundredths higher with negative taken where the coil attaches to the
> engine. I expect that a bad ground would create a much higher difference,
> but I don't know how big a difference it would be. I don't think most
> mechanics are going to be checking for differences measured in hundredths of
> volts.
>
> I still get code 12. The battery had been disconnected in the shop. My OBD
> reader can reset OBD codes, but not the 12 code. Does it reset after 50
> start cycles? Does start cycle mean starting the engine and then stopping it
> without any requirement to let if run for a while or get to closed loop?
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
>> Sometimes the cables can rot inside the clamps which is why the meter test
>> is a good one just to make sure.
>>
>> It wouldn't hurt to meter the engine block with the volt test also.
>>
>> Code 55 should be the only one.
>>
>> Mike
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Those volt readings are within any tolerances, when you start to see
tenths, you have issues.

Could have just been a bad pump, it happens.

I believe the code will reset with a key start count like it counts to
give you codes.

Mike

Joe_M wrote:
> Grand back with new fuel pump and running.
>
> I checked voltages with digital meter while engine idling with lights on,
> wipers on, and heater fan on. The reading was just over 13.5 volts across
> the battery terminals. About 2 to 4 hundredths of a volt higher with
> negative taken from bolt attaching coolant overflow reservoir to body. About
> 3 to 5 hundredths higher with negative taken where the coil attaches to the
> engine. I expect that a bad ground would create a much higher difference,
> but I don't know how big a difference it would be. I don't think most
> mechanics are going to be checking for differences measured in hundredths of
> volts.
>
> I still get code 12. The battery had been disconnected in the shop. My OBD
> reader can reset OBD codes, but not the 12 code. Does it reset after 50
> start cycles? Does start cycle mean starting the engine and then stopping it
> without any requirement to let if run for a while or get to closed loop?
>
> Thanks,
>
> Joe M
>
> "Mike Romain" <romainm@sympatico.ca> wrote in message
> news:4695486b$0$6292$9a6e19ea@unlimited.newshostin g.com...
>> Sometimes the cables can rot inside the clamps which is why the meter test
>> is a good one just to make sure.
>>
>> It wouldn't hurt to meter the engine block with the volt test also.
>>
>> Code 55 should be the only one.
>>
>> Mike
>
>

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M proclaimed:

> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?

OK, it *could* happen, but I'd try a different mechanic.

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M proclaimed:

> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?

OK, it *could* happen, but I'd try a different mechanic.

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M proclaimed:

> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?

OK, it *could* happen, but I'd try a different mechanic.

Re: '97 Grand fuel pump relay killed fuel pump?
 

Joe_M proclaimed:

> I have a '97 Grand Cherokee 4x4 that has had a myriad of ignition problems
> (well ... maybe one problem with a myriad of 'solutions'). I finally
> replaced the computer and the problems stopped for a couple of months. This
> week the engine died a couple of times while driving in hot weather and then
> would start again after a few minutes. It then began not starting when
> driven and then parked for about a half hour. It finally would not start
> again. No codes, no engine light. Towed to mechanic.
>
> He says the fuel pump and the fuel pump relay are bad. It was replaced last
> year. The mechanic says the relay may have burnt out the fuel pump over time
> by creating spikes and low voltage. I don't know much about the system, but
> that sounds very strange for relays. Is this a likely diagnosis?

OK, it *could* happen, but I'd try a different mechanic.