94 Jeep Stalling After Start

JCF05002

MEMBER
1994 JEEP GRAND CHEROKEE
170,000 MILES

Ok, I changed the fuel filter, yesterday. I added lucas injector cleaner and heet after, I changed the filter. Lots of white smoke came out of the exhaust. I guess that was the heet working. After about 30 mins, the white smoke was almost gone. It ran smooth, I put more gas in it and parked it for the night. I cranked it today and It started, but stalled within 5 seconds. The check engine light comes on and everytime I crank it, the jeep starts right back up and stalls out in 5 seconds. If I give it some gas, it runs until I take my foot off of the accelerator and stalls out immediately. I don't understand what could be wrong. Any ideas?

7 Replies

CARADIODOC

MECHANIC
33,864 POSTS

Did you disconnect the battery or run it dead?

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Friday, June 22nd, 2012 AT 6:48 PM

JCF05002

MEMBER
5 POSTS

Thanks for replying. It's not the battery. See, I just found out that if I put one foot on the break and keep one foot on the accelerater, very lightly - I'm able to put the jeep in whatever gear and drive it. But my foot must be on the accelerator at all times. A backyard mech I just called tells me it can be a clogged fuel line, injectors or iac. He said it could also be a cp sensor issue. He assured me it's not the fuel pump, because the jeep wouldn't even start in the first place. But he's kinda shakey at times, I only contact him when I'm on a tight budget. Any advice?

Thanks!

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Friday, June 22nd, 2012 AT 8:09 PM

CARADIODOC

MECHANIC
33,864 POSTS

Yup. I can discount all of those things. Other than on the diesel trucks, you will never solve a running or stalling problem on a Chrysler product by replacing the fuel filter. A plugged screen on the pickup tube in the tank is more likely to cause stalling when the largest volume of fuel is pumped, which is during coasting.

There aren't large enough particles in the fuel line to plug it. If multiple injectors were plugged, you'd have a misfire when the engine needs the largest volume of fuel which is under load and accelerating. The engine won't restart if the crankshaft position sensor or camshaft position sensor are bad.

The automatic idle speed motor, (AIS), also called the "idle air control" (IAC) motor could be inoperative but that isn't very common. Besides maintaining idle speed, it also gives you the nice idle "flare-up" to 1500 rpm when you start the engine. If you aren't getting that, the common cause is the battery was disconnected or run dead recently. If so, the Engine Computer lost its memory and has to relearn "minimum throttle" before it will know when it must be in control of idle speed. To meet the conditions for the relearn to take place, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.

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Friday, June 22nd, 2012 AT 8:26 PM

JCF05002

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Ok, you just blew my mind with info! I read your post 3 times. Thank You, Caradiodoc! When I crank my truck I only get about 400-600 rpm. I looked up a video on how to clean an iac, just in case. But I will try the hyw speed test, 1st. And as far as the plugged screen, Is that expensive? Can I unplug it myself? I have a friend that owns an oil shop. I could probably get him to let me use a bay, this evening and pull the tank to try to unplug it. I want to check all of these possible fixes. You're being Very helpful!

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Friday, June 22nd, 2012 AT 8:51 PM

JCF05002

MEMBER
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I'm Just Back To Say, Thanks, Again! - In All Actuality, It WAS The IAC. A Very Easy DIY Fix And Only $60. More Than Worth The Price VS How Worse It Could Have Been! Thanks For The Impeccable Info, Caradiodoc!