Mike Romain

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
>
>

Mike Romain

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
>
>

Mike Romain

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
>
>

Lon

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.

Lon

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.

Lon

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.

Lon

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.