Random-ish stalling

First off, let me apologize for starting another stalling thread. I'm new to these forums and I'm not very skilled with vehicles. I read through most of the other stalling threads but couldn't find anything that closely resembled my problem.

With that said, I have been having a problem with my Jimmy (96, 4.3l, 155,000+ miles) stalling at very random times. It has happened 7 times in the past three months, usually more than once in an hours time (4 times one day, 1 time another day, and 2 times another day).

When this first occured it seemed as though I was out of gas. While going uphill the vehicle died without really sputtering. It was easy to start back up and get going again, but stalled twice more, once while going uphill and once while on a level surface. I figured the gas gauge was stuck, but I filled the tank up and realized that the gauge must have been right. After filling the tank the vehicle stopped stalling.

The next time it stalled was while I was making a sharp right hand turn. Once again the fuel gauge was right between 1/4 and 1/2 of a tank. Again it was easy to start back up and get to the gas station.

The last time it did it I was again in the middle of a right hand turn with about 1/4 a tank of gas. It died on me twice before I got to the gas station to fill it up.

Now, is someone else had this problem under those conditions, I would say that he had a bad gas gauge. However, every time this has happened the amount of gas I put in is the correct amount needed to fill the tank according to the gauge.

My other theory is that there is a hose in the gas tank that pulls the gas into the engine and that it is broken in half. That would explain why this always happens somewhere around 1/4 a tank why it happens when making turns. But, I'm no mechanic and this is just a guess. One of the know-it-alls that I work with told me it sounded like heat lock because it happens on hot days after a lot of driving, but I don't know if I trust her.

The only "under the hood" problems I have had to deal with recently was a bad O2 sensor and a cracked vaccuum hose. No problems with the fuel pump, engine components or cooling system yet, so I'm crossing my fingers!

You might want to try the gas cap. It could be a pressure problem.

Here I go again, but most of us with high mileage trucks forget the O2 sensors. Mine failed to slightly rich, the computer corrected by leaning out the mixtures and the truck would stall (sometimes) on sweeping right turns, like freeway on-ramps, when the engine wouldn't run on the lean mixture. It started right back up, because the computer used stored data which uses a slightly rich mixture.
You can drop 100 bucks on an OBDII decoder and with a computer or laptop read all of the sensor outputs. Or you can just replace the sensors for about 100 bucks.
I believe you have 3 sensors on your year, the one behind the cat is only to monitor the cat the other two tell the computer about the oxygen remaining in the exhaust so that it can adjust the fuel injector "on" time to control the mixture.
Rockauto.com has sensors for about $42 eac,h plus you'll need a Sensor socket for about $5, half hour under the truck and your done.
Let us know what you find
See ya
94

Thanks for the suggestions.

My Jimmy has graduated from the stalling at slow speeds stage to trying to die while doing 70+. I about had a heart attack when it started bucking on me yesterday, but I managed to drive it the 50 miles I needed to get home. When it would start to buck I would let off the gas for a second or two and then hammer it. It would jump pretty hard, but that was the only way I could keep it running.

My father seems to think it has something to do with the O2 sensors, the vaccuum lines, or he says its possible that I have water in my gas. I have a feeling that the transmission is going out, but I'm no mechanic. However neither of us has the equipment or time to find out what it is for sure so I'm taking it to the mechanic today.

I'm bumping this thread up because it sounds almost exactly like the problem I'm having.

It'll go a week or more without a problem, then give me trouble for a couple of days. I've had fuel filters replaced twice and I've replaced the air filter.

Usually, but not always, the problem will show up after I've been driving for a while and I slow down to make a sharp turn. An example is exiting an interstate. After the initial problem, it keeps up for a while. If I try to give it too much gas, it seems to choke it out. If I go light on the pedal, it will keep running, but not let me accelerate.

I've noticed the problem mostly when I have about 1/4 tank of gas, but it has happened when I have more. Filling the tank, oddly, seems to help.

It's a 1998, 4.3l V6, just over 121,000 miles.

Thanks.

change fuel filter if it hasn't been done in last 30k

check all vacuum lines for dry rot and cracking

remove and clean EGR and IAC

use TB cleaner to clean throttle body, especially where the butterfly pivots

check fuel pressure (once with ignition ON, engine OFF - and again with the engine running)

if SES light is on, get the codes read at Autozone




I'm bumping this thread up because it sounds almost exactly like the problem I'm having.

It'll go a week or more without a problem, then give me trouble for a couple of days. I've had fuel filters replaced twice and I've replaced the air filter.

Usually, but not always, the problem will show up after I've been driving for a while and I slow down to make a sharp turn. An example is exiting an interstate. After the initial problem, it keeps up for a while. If I try to give it too much gas, it seems to choke it out. If I go light on the pedal, it will keep running, but not let me accelerate.

I've noticed the problem mostly when I have about 1/4 tank of gas, but it has happened when I have more. Filling the tank, oddly, seems to help.

It's a 1998, 4.3l V6, just over 121,000 miles.

Thanks.

jumping on board this thead also. I have a 99 envoy 101,200mi. doing the same thing. happens mostly in the afternoon when the car is hot. mostly coming to a stop or decelerating of any kind. when i get it stopped it starts right back up. but continues to happen. i replaced alot trying to solve this problem. battery, altenator, tensioner, belt, fuel filter. pls. help us figure this out. i'm very hands on so, what ever suggestions you people have, i will try them!

Ignition wiring harness.
Had the same problem with a 97 Jimmy and finally narrowed it down and found the contactors (what your key switch rolls on) were burnt causing an intermintent "skip". Replaced and never happened again. If you replace it you can crack open the old contactor to see what I mean. Took me over a year to find the problem.

I doubt this would fix it but it could be a TPS that's bad as well... I had that screw up in my Blazer

clean your carborator

My 95 Jimmy with 174,000 tends to stall under braking and turns (either direction) when it gets under 1/2 tank. It runs fine on the highway, with no bucking or anything. I have a SES code of 441 purge flow issue. I have changed the gas cap, but still have the code.
If I can get this problem fixed along with the ABS light, I think I'll be happy with the car. I just don't like the stalling becasue wife uses the car shuttling the kids around, and she almost got rear-ended twice.

See my post above. Ignition Wiring Harness

There should have been a recall judging from the type of problems and safety issues it causes. It was only like $60 and took about an hour to install (runs from the switch to the base of the steering column). This is not a shot in the dark, it fixed my stalling problem and I would bet it would fix yours.

I'm not sure if this is the problem, but it was with my 92 Jimmy, if the 4.3L are the same motor.

I put about $600 into a fuel pump, and 3 or 4 visits with labor fixing ground wires before my dad and I took it to a dealer mechanic that my dad knows. He couldn't find the problem at first, but the last thing he checked was a connector one wires running to the injectors. When pulled apart, it looks like two wires poking out inside the connector, and one of them was bent, causing a bad connection and my truck to completely die when driving down the road. He bent the connector back, and never had problems since!

Just a thought.