Jeep Cherokee hard starting, part II
 

Hi all -

I have a 1991 Jeep Cherokee Laredo with the in-line 6 and
auto-transmission. I have been fighting a hard start problem, which I
posted on this forum about a month ago. My suspicions at that point
were the fuel pump or the crankshaft position sensor. I've noticed
lately some different behavior, and wanted to see what folks thought of
these symptoms. Here goes. If I just sit and crank it, it takes
forever to eventually catch and start. What I've developed is a way to
almost always get it to start. I floor the gas, start to crank it, but
after about 3 seconds or so, I stop cranking it by turning the key to
the ON position from START. While I do this, I keep the gas floored.
Almost always, when I stop cranking and turn the key from START to ON,
*then* it catches and starts running!! At first I thought this was a
fluke, but the method has been consistent for about the last dozen
starts or so. I'm at a loss here, can anyone offer anything?

Thanks,
Bud

Re: Jeep Cherokee hard starting, part II
 

I can't cay about Jeep fuel injection in particular but generally,
pressing the gas while cranking is a good way to blow the airbox off.
What you describe is typical behavior for older fuel injection systems.
The fuel pressure in the rail is bleeding down when the car sits. The
first time you crank it, it takes forever to fire because there's no
pressure in the system.
If you crank it a couple turns, stop, then crank a couple turns more,
you'll find it lites without any pressing the gas. The first time it
spins, it builds pressure, then the next time, it goes.
You can experiment on how many times it needs to go round before it has
enough pressure to lite and once you get it figured out it'll be the
same every time.
May need to stop and start 3 or 4 times to get it to go... My
girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
seconds of cranking.
Continuous cranking won't do it though.

Bud wrote:
> Hi all -
>
> I have a 1991 Jeep Cherokee Laredo with the in-line 6 and
> auto-transmission. I have been fighting a hard start problem, which I
> posted on this forum about a month ago. My suspicions at that point
> were the fuel pump or the crankshaft position sensor. I've noticed
> lately some different behavior, and wanted to see what folks thought of
> these symptoms. Here goes. If I just sit and crank it, it takes
> forever to eventually catch and start. What I've developed is a way to
> almost always get it to start. I floor the gas, start to crank it, but
> after about 3 seconds or so, I stop cranking it by turning the key to
> the ON position from START. While I do this, I keep the gas floored.
> Almost always, when I stop cranking and turn the key from START to ON,
> *then* it catches and starts running!! At first I thought this was a
> fluke, but the method has been consistent for about the last dozen
> starts or so. I'm at a loss here, can anyone offer anything?
>
> Thanks,
> Bud
>

Re: Jeep Cherokee hard starting, part II
 

I can't cay about Jeep fuel injection in particular but generally,
pressing the gas while cranking is a good way to blow the airbox off.
What you describe is typical behavior for older fuel injection systems.
The fuel pressure in the rail is bleeding down when the car sits. The
first time you crank it, it takes forever to fire because there's no
pressure in the system.
If you crank it a couple turns, stop, then crank a couple turns more,
you'll find it lites without any pressing the gas. The first time it
spins, it builds pressure, then the next time, it goes.
You can experiment on how many times it needs to go round before it has
enough pressure to lite and once you get it figured out it'll be the
same every time.
May need to stop and start 3 or 4 times to get it to go... My
girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
seconds of cranking.
Continuous cranking won't do it though.

Bud wrote:
> Hi all -
>
> I have a 1991 Jeep Cherokee Laredo with the in-line 6 and
> auto-transmission. I have been fighting a hard start problem, which I
> posted on this forum about a month ago. My suspicions at that point
> were the fuel pump or the crankshaft position sensor. I've noticed
> lately some different behavior, and wanted to see what folks thought of
> these symptoms. Here goes. If I just sit and crank it, it takes
> forever to eventually catch and start. What I've developed is a way to
> almost always get it to start. I floor the gas, start to crank it, but
> after about 3 seconds or so, I stop cranking it by turning the key to
> the ON position from START. While I do this, I keep the gas floored.
> Almost always, when I stop cranking and turn the key from START to ON,
> *then* it catches and starts running!! At first I thought this was a
> fluke, but the method has been consistent for about the last dozen
> starts or so. I'm at a loss here, can anyone offer anything?
>
> Thanks,
> Bud
>

Re: Jeep Cherokee hard starting, part II
 

I can't cay about Jeep fuel injection in particular but generally,
pressing the gas while cranking is a good way to blow the airbox off.
What you describe is typical behavior for older fuel injection systems.
The fuel pressure in the rail is bleeding down when the car sits. The
first time you crank it, it takes forever to fire because there's no
pressure in the system.
If you crank it a couple turns, stop, then crank a couple turns more,
you'll find it lites without any pressing the gas. The first time it
spins, it builds pressure, then the next time, it goes.
You can experiment on how many times it needs to go round before it has
enough pressure to lite and once you get it figured out it'll be the
same every time.
May need to stop and start 3 or 4 times to get it to go... My
girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
seconds of cranking.
Continuous cranking won't do it though.

Bud wrote:
> Hi all -
>
> I have a 1991 Jeep Cherokee Laredo with the in-line 6 and
> auto-transmission. I have been fighting a hard start problem, which I
> posted on this forum about a month ago. My suspicions at that point
> were the fuel pump or the crankshaft position sensor. I've noticed
> lately some different behavior, and wanted to see what folks thought of
> these symptoms. Here goes. If I just sit and crank it, it takes
> forever to eventually catch and start. What I've developed is a way to
> almost always get it to start. I floor the gas, start to crank it, but
> after about 3 seconds or so, I stop cranking it by turning the key to
> the ON position from START. While I do this, I keep the gas floored.
> Almost always, when I stop cranking and turn the key from START to ON,
> *then* it catches and starts running!! At first I thought this was a
> fluke, but the method has been consistent for about the last dozen
> starts or so. I'm at a loss here, can anyone offer anything?
>
> Thanks,
> Bud
>

Re: Jeep Cherokee hard starting, part II
 

I can't cay about Jeep fuel injection in particular but generally,
pressing the gas while cranking is a good way to blow the airbox off.
What you describe is typical behavior for older fuel injection systems.
The fuel pressure in the rail is bleeding down when the car sits. The
first time you crank it, it takes forever to fire because there's no
pressure in the system.
If you crank it a couple turns, stop, then crank a couple turns more,
you'll find it lites without any pressing the gas. The first time it
spins, it builds pressure, then the next time, it goes.
You can experiment on how many times it needs to go round before it has
enough pressure to lite and once you get it figured out it'll be the
same every time.
May need to stop and start 3 or 4 times to get it to go... My
girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
seconds of cranking.
Continuous cranking won't do it though.

Bud wrote:
> Hi all -
>
> I have a 1991 Jeep Cherokee Laredo with the in-line 6 and
> auto-transmission. I have been fighting a hard start problem, which I
> posted on this forum about a month ago. My suspicions at that point
> were the fuel pump or the crankshaft position sensor. I've noticed
> lately some different behavior, and wanted to see what folks thought of
> these symptoms. Here goes. If I just sit and crank it, it takes
> forever to eventually catch and start. What I've developed is a way to
> almost always get it to start. I floor the gas, start to crank it, but
> after about 3 seconds or so, I stop cranking it by turning the key to
> the ON position from START. While I do this, I keep the gas floored.
> Almost always, when I stop cranking and turn the key from START to ON,
> *then* it catches and starts running!! At first I thought this was a
> fluke, but the method has been consistent for about the last dozen
> starts or so. I'm at a loss here, can anyone offer anything?
>
> Thanks,
> Bud
>

Re: Jeep Cherokee hard starting, part II
 

Clay hacked up a hairball and the stain left behind looked like this:

>I can't cay about Jeep fuel injection in particular but generally,
>pressing the gas while cranking is a good way to blow the airbox off.
>What you describe is typical behavior for older fuel injection systems.
>The fuel pressure in the rail is bleeding down when the car sits. The
>first time you crank it, it takes forever to fire because there's no
>pressure in the system.
>If you crank it a couple turns, stop, then crank a couple turns more,
>you'll find it lites without any pressing the gas. The first time it
>spins, it builds pressure, then the next time, it goes.
>You can experiment on how many times it needs to go round before it has
>enough pressure to lite and once you get it figured out it'll be the
>same every time.
>May need to stop and start 3 or 4 times to get it to go... My
>girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
>seconds of cranking.
>Continuous cranking won't do it though.

Have to agree here with Clay. Should not apply any gas during
cranking. It's easy on the I-6 to check the fuel pressure with a
guage. You might try checking with your local auto parts store to see
if they rent one. Mine did and that's when I found no pressure was
built up to start. In my case, no voltage is going to the tank.

You should have at least 20lbs pressure before cranking and over 30
when running. If you're not getting any pressure, your fuel pump might
be going bad. Good luck!

~Casper
<Jeepers... It'sa jeep thing!>

Re: Jeep Cherokee hard starting, part II
 

Clay hacked up a hairball and the stain left behind looked like this:

>I can't cay about Jeep fuel injection in particular but generally,
>pressing the gas while cranking is a good way to blow the airbox off.
>What you describe is typical behavior for older fuel injection systems.
>The fuel pressure in the rail is bleeding down when the car sits. The
>first time you crank it, it takes forever to fire because there's no
>pressure in the system.
>If you crank it a couple turns, stop, then crank a couple turns more,
>you'll find it lites without any pressing the gas. The first time it
>spins, it builds pressure, then the next time, it goes.
>You can experiment on how many times it needs to go round before it has
>enough pressure to lite and once you get it figured out it'll be the
>same every time.
>May need to stop and start 3 or 4 times to get it to go... My
>girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
>seconds of cranking.
>Continuous cranking won't do it though.

Have to agree here with Clay. Should not apply any gas during
cranking. It's easy on the I-6 to check the fuel pressure with a
guage. You might try checking with your local auto parts store to see
if they rent one. Mine did and that's when I found no pressure was
built up to start. In my case, no voltage is going to the tank.

You should have at least 20lbs pressure before cranking and over 30
when running. If you're not getting any pressure, your fuel pump might
be going bad. Good luck!

~Casper
<Jeepers... It'sa jeep thing!>

Re: Jeep Cherokee hard starting, part II
 

Clay hacked up a hairball and the stain left behind looked like this:

>I can't cay about Jeep fuel injection in particular but generally,
>pressing the gas while cranking is a good way to blow the airbox off.
>What you describe is typical behavior for older fuel injection systems.
>The fuel pressure in the rail is bleeding down when the car sits. The
>first time you crank it, it takes forever to fire because there's no
>pressure in the system.
>If you crank it a couple turns, stop, then crank a couple turns more,
>you'll find it lites without any pressing the gas. The first time it
>spins, it builds pressure, then the next time, it goes.
>You can experiment on how many times it needs to go round before it has
>enough pressure to lite and once you get it figured out it'll be the
>same every time.
>May need to stop and start 3 or 4 times to get it to go... My
>girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
>seconds of cranking.
>Continuous cranking won't do it though.

Have to agree here with Clay. Should not apply any gas during
cranking. It's easy on the I-6 to check the fuel pressure with a
guage. You might try checking with your local auto parts store to see
if they rent one. Mine did and that's when I found no pressure was
built up to start. In my case, no voltage is going to the tank.

You should have at least 20lbs pressure before cranking and over 30
when running. If you're not getting any pressure, your fuel pump might
be going bad. Good luck!

~Casper
<Jeepers... It'sa jeep thing!>

Re: Jeep Cherokee hard starting, part II
 

Clay hacked up a hairball and the stain left behind looked like this:

>I can't cay about Jeep fuel injection in particular but generally,
>pressing the gas while cranking is a good way to blow the airbox off.
>What you describe is typical behavior for older fuel injection systems.
>The fuel pressure in the rail is bleeding down when the car sits. The
>first time you crank it, it takes forever to fire because there's no
>pressure in the system.
>If you crank it a couple turns, stop, then crank a couple turns more,
>you'll find it lites without any pressing the gas. The first time it
>spins, it builds pressure, then the next time, it goes.
>You can experiment on how many times it needs to go round before it has
>enough pressure to lite and once you get it figured out it'll be the
>same every time.
>May need to stop and start 3 or 4 times to get it to go... My
>girlfriends 91 Cherokee does anyway. Usually it hits on the third 1½
>seconds of cranking.
>Continuous cranking won't do it though.

Have to agree here with Clay. Should not apply any gas during
cranking. It's easy on the I-6 to check the fuel pressure with a
guage. You might try checking with your local auto parts store to see
if they rent one. Mine did and that's when I found no pressure was
built up to start. In my case, no voltage is going to the tank.

You should have at least 20lbs pressure before cranking and over 30
when running. If you're not getting any pressure, your fuel pump might
be going bad. Good luck!

~Casper
<Jeepers... It'sa jeep thing!>

Re: Jeep Cherokee hard starting, part II
 

Then again, could be electrical. Your battery in good shape?
Sounds like the starter is taking all the fire away from the ignition.
Soon as you release the key, it has enough spark to run maybe?
I dunno...

Bud wrote:
....when I stop cranking and turn the key from START to ON,
> *then* it catches and starts running!! A...