93 JGC Starts then dies - won't continue to run

[joejoe41]

My son has a 1993 Jeep Grand Cherokee. He bought it with a bad fuel pump. That has been replaced, now the car starts very easy, but won't run past 1 second. It keeps dying. There have been a couple of time it ran for about 2-3 seconds, he can rev it up a little, but then it dies. Everytime it dies, it is very sudden, like it just shuts down.

Does the security system allow the car to start and then shuts down?
Relay problem?

Any hints or suggestions would really be appreciated!!!!

Thanks
John
[email protected]

[GregA]

John,

First of all - Welcome to the forum.

See if you (or your son) can get any codes out of it.

Turn the key to ON-OFF-ON-OFF-ON within a few seconds and then watch for the Check Engine light to flash. Count the flashes and pauses and record them (they should be 2 digit numbers). Then post the numbers and we will see what we can do.

Could be a few things keeping it from running, including the security system (especially if it is aftermarket).

Take Care,

[bringselpup]

Once it's running the computer relies on sensors to tell it what to do. For example if no input from the crankshaft position sensor then the PCM thinks the motor isn't turning so it will kill the voltage to the fuel pump etc.

Check engine light on? If so get us the codes. 3 Key on/off sequences last one leave it on and watch the check engine light. It will flash 2 digit codes at you and end with two fives.

If you have no codes I'd start poking around the throttle body. The IAC gets dirty on these things so maybe it's stuck. People have luck using large amounts of carb cleaner stuff to clean it up but most also need to disassemble it to really clean it up.

Who did the fuel pump? A shop shouldn't have given the vehicle back if it wouldn't run longer than 1 sec.

[joejoe41]

No codes from the check engine. My son bought the jeep not running and replaced the fuel pump. I think it is the factory security system.

How do you permanently disable the factory security system? We have tried the key to lock/unlock on the lift gate, but the vehicle still shuts down after it starts. I have bypassed the fuel pump relay, but don't know where to go from here.

Thanks
John

[bringselpup]

The info I've been able to uncover says you're right on trying to lock and unlock the liftgate. That's how to reset the alarm.

Unfortunately I also found info that says the alarm is in the body control module. To actually remove the alarm you'd need to find a BCM without factory theft. I can only wonder if that would then mean you'd have to change the main (PCM) computer too.

It might be cheaper to get your hands on a replacement remote.

I saw talk about valet mode but no one definitively wrote how to put the vehicle into that mode. Maybe a local dealer can tell you?

I have a 93 owners manual somewhere. I wanted it for something else the other day and I can't locate it. If I do maybe it will say something.

[dszilke1]

factory remote resets the alarm. I changed a battery and got the same results. Using the remote to lock and unlock the doors resets the alarm.

Scott

[valhalla3]

I have a 93 Grand Cherokee that has a similar problem At some point my Jeep started cranking over more than normal when starting. I realized that I wasn't hearing the little buzz when you first turn the key on. At that time I thought the sound was the fuel pump. I found as long as I turned the key off and on again until I heard the buzz it would start right up. Usually I only had to turn the key off and on once. This went on for a few months until recently it just keeps cranking over. I can hear the little buzz still but it sounds a little different. Occassionally it would start up and die right out again. I was told that the buzzing sound is the fuel pump relay rather than the fuel pump itself.

I don't get any codes as my check engine light does not flash at all. Can I bypass the relay to determine if that is a problem or not? Does anyone have a pin out of the relay or socket or can tell me how to do it?

Any help with this would be great!

Thanks!

Valhalla

[89ltd]

sounds like the auto shut down relay, is it a 4.0 L engine??

[dksob81]

Your Problem is the Idle Air Control Valve. Replace it, be sure to disconnect the battery, before removing/replacing the IAC. Be sure to adjust it according to the directions that come with the new IAC Valve.

You could also try this, start the jeep and hold the gas pedal lightly keep the engine running at about 1500 Rpms. Do this for a few minutes then let go, does it continue to run?

I had this problem in my 94 about a year ago, it would start then die immediately, if I held the gas in for a minute or so it would be fine and there was a couple occasions that right after getting it started when I come to a stop it would die, well I replace the IAC and it didn't help, but I knew it was the problem and figured I prolly got a bad part from autozone, so I took it back and got a new one put and I was about to put it on and remembered that I forgot to d/c the battery the first time, so I was sure to disconnect it this time. Well it's been a lil over a year and haven't had any problems since.

I don't know if I just got a bad parts from autozone or disconnecting the battery did the trick but either way it works now.

[Scandent]

I have a similar problem with my 93.
Havent been able to figure it out; see my post dated 4/2/2006.

Cycling the alarm (force it to trigger with the window open and manually unlocking the door, then de-activating with key will always reset mine so it will start.

A couple have told me this is due to old battery condition; I watched the voltmeter while cranking last time and it did indeed go below 9 volts; I think Ill try a new battery first, it needs one anyhow (4 years +)