91 Cherokee start then die

Hi Everyone,

My 91 Cherokee Briarwood, 4WD, 6 Cyl. starts fine and then dies after 1 -3 seconds.

It started with an electrical problem. Got a brand new battery and it died within a week, got a jump and the jeep made it home (about 5 miles) but i noticed when i slowed down at stop lights it would almost stall, i figured this was related to the battery problem. When i parked it in the driveway the radio and door alarms were working, when i went out the next day to start it the battery was dead! Traced it down to the power antennae (after testing alternator, replacing coil, checking dist), it was stuck and would pull 5 Amps every 5 secs or so, pulled the fuse for that and the battery held a charge!

Now it will start perfectly and run normally(no sputtering) for 1 to 3 seconds then die. After starting it usually idles up to about 2kRPM then stabalizes at 1.5 but it cant even make it to 2. If I push the gas in before i start it will make it to about 3KRPM then it goes back down. I did notice the antifreeze was pretty low so i added some. Its not storing a code, the check engine comes on for a second when it stalls though, which i think is normal if the vehicle fails..? If there's no idiot light does that eliminate the possibility of a sensor getting a bad reading (TPM, Oil Pressure, CPS, etc?). I can hear the fuel pump kick on when i put the key to the on position and i have swapped relays on auto shut down and fuel pump to no avail. I have also tried bypassing the balast resistor and resetting the ECM by touching the pos cable to neg for 30 secs. Anyone have any ideas?

Thanks!!

ignition switch or coil are my guess from the internet

mac 'damn electrical gremlins' gyvr

Tried a new coil...I was almost thinking ignition system is out of the equation since it starts..I thought about ignition switch but the on position should be good since fuel pump primes, right? Or does it go into another mode after start?

I have also tried pulling the vacuum on the fuel reg. I removed the filter and blew through it to make sure there was good flow. I'm almost thinking its the fuel pump but dont have a pressure tester, looking for a friend who knows someone with one :/. If i disconnect the the intake it shoots gas about 5 inches across the hood.

Could it be electrical..? It almost seems like something it telling it to shut down..

91 XJ Start then DIE!

Hi Everyone,

My 91 Cherokee Briarwood, 4WD, 6 Cyl. 173K Miles, starts fine and then dies after 1 -3 seconds.

It started with an electrical problem. Got a brand new battery and it died within a week, got a jump and the jeep made it home (about 5 miles) but i noticed when i slowed down at stop lights it would almost stall, i figured this was related to the battery problem. When i parked it in the driveway the radio and door alarms were working, when i went out the next day to start it the battery was dead! Traced it down to the power antennae (after testing alternator, replacing coil, checking dist), it was stuck and would pull 5 Amps every 5 secs or so, pulled the fuse for that and the battery held a charge!

Now it will start perfectly and run normally(no sputtering) for 1 to 3 seconds then die. After starting it usually idles up to about 2kRPM then stabalizes at 1.5 but it cant even make it to 2. If I push the gas in before i start it will make it to about 3KRPM then it just quits. I did notice the antifreeze was pretty low so i added some. The check engine comes on for a second when it stalls though, which i think is normal if the vehicle fails..? If there's no idiot light when its in the on postiion does that eliminate the possibility of it thowing a code or a sensor getting a bad reading (TPM, Oil Pressure, CPS, etc?)?

I can hear the fuel pump kick on when i put the key to the on position and i have swapped relays on auto shut down and fuel pump to no avail. I have also tried bypassing the balast resistor and resetting the ECM by touching the pos cable to neg for 30 secs. I tried pulling the vacuum on the fuel reg. I removed the filter and blew through it to make sure there was good flow. I'm almost thinking its the fuel pump but dont have a pressure tester, looking for a friend who knows someone with one :/. If i disconnect the the intake it shoots gas about 5 inches across the hood.

Could it be electrical..? It almost seems like something it telling it to shut down..

Anyone have any ideas?

Thanks!!
Adam

i had the exacty issue on my 95 a long time ago. it would start and then die, repeatedly, sometimes it would run eventually...then it finally just quit running. i replaced all the sensors tps, cps, all of them cause that's what people on this forum told me to do all those years ago...

finally got fed up and strapped it to the dealer where they charged me over 300 bucks to replaced the ignition switch...

also had the exact same issue in my 79 ford bronco about 6 months later...and a new ignition switch fixed it to...

mac 'was my year for ignition switches' gyvr

You can jumper the ignition switch to see if that is your problem.
However, I'll bet it's the PCM. I have one here from a junked 1992 XJ that does the exact same 3 second run.
I believe there is a timer in the PCM that switches from crank mode to idle mode at 3 seconds.
.
What is the number on your PCM, 56027528 or 56027488?

dennis461 said:

You can jumper the ignition switch to see if that is your problem.
However, I'll bet it's the PCM. I have one here from a junked 1992 XJ that does the exact same 3 second run.
I believe there is a timer in the PCM that switches from crank mode to idle mode at 3 seconds.
.
What is the number on your PCM, 56027528 or 56027488?

Click to expand...

the 3 second thing with the PCM is sometimes the securakey, but that was more an issue with grand cherokees...

oh yeah, when my ignition switch was bad, people told me that my PCM was bad too...

mac 'dealer ignition switch replacement was prolly cheaper than PCM replacement' gyvr

Re: 91 XJ Start then DIE!

Do this:

Hook up a voltmeter to the hot lead from the ignition switch to the fuel pump relay connector. Start it up and let it run while you observe the voltmeter--is there 12 volts present? Is there 12 volts present right up to its dying or does the voltage go away before it dies?

Post up what you find.

Check and see if the exhaust is plugged, had my 87' get the cat clogged. As a last measure I got pissed off and cut it off...I would suggest un-bolting but it is up to you. Too much back pressure kept killing the motor after 2-3 seconds. Long shot but free to check...

How can i jumper the ignition switch dennis??

I can feel air coming out of the exhaust, seems pretty normal and the cat is fairy new, 3 yrs or so, i guess that doesn't mean it could have collapsed though.

I'm thinking the battery drain form the power antennae has something to do with it, if this thing was pulling 5A after the battery was dead could it have killed the PCM?

Re: 91 XJ Start then DIE!

And how would i do that..? Sorry..i'm a newb. I have the haynes manual for my model but i'm not seeing where the fuel pump relay is in reference to the ignition switch.

its changed, now when i start sometimes it will start for a second and others it will not, im thinking the fuel pump may not be giving the right pressure...?

Re: 91 XJ Start then DIE!

Your fuel pump relay is in the PDC--power distribution center--passenger's side fenderwell. Pull the cover, there is a relay/fuse layout diagram in it.

alroosa--I merged your two threads into one.

Thanks for merging them Joe!

I have swapped the relays in the PDC on the fuel pump with the AC. Which lead on the relay do i test? Also is the ignition control is under the hood as well?

Thanks

Your 91 has the key/remote rod/ignition switch arrangement.

The ignition switch is located on the steering column towards the floor board.

K, ill take a look. Then i need a really long jumper cable from the fuel pump relay..? which pin on the relay do i connect the jumper to?

So not the ignition switch....or the fuel pump, borrowed a pressure tester from autozone. The pressure was 31 @ prime 39 running...the pressure didnt change when unplugging the vacuum line from the regulator so i replaced it...didnt work.

The exhaust gets a good push form the muffler and it will stay running off of carb cleaner sprayed in the throttle body...

:doh:
Any other ideas...?

alroosa said:

So not the ignition switch....or the fuel pump, borrowed a pressure tester from autozone. The pressure was 31 @ prime 39 running...the pressure didnt change when unplugging the vacuum line from the regulator so i replaced it...didnt work.

The exhaust gets a good push form the muffler and it will stay running off of carb cleaner sprayed in the throttle body...

:doh:
Any other ideas...?

Click to expand...

You have a vacuum issue. There is no vacuum being applied to the FPR when the engine is running, the fuel pressure needs to be 31 psi until you get on the throttle and the vacuum naturally drops, then the pressure rises to 39 psi. Test/check your vacuum supply to the FPR.

You may also have a related intake leak, resulting in the excessive idle speed.

Thanks will check the vacuum, The elbow is a little cracked but i took it off and tried it with a vacuum line without elbows and no change..where does the vacuum start @?

also sprayed carb cleaner around the intake manifold while starting it and it didnt idle up like there was a broken gasket..