Intermittent Stalling Problem

[Cerulean]

Hello all,

I have a problem that I'm hoping I can get some help with. I recently bought an old 1994 Yukon and everything seemed fine for the first couple of weeks. Then it started to stall out on me while I was driving. There will be no warning at all, such as sputtering or backfiring or such. It will just die. I usually don't even notice it has stalled until I go to hit the gas again and nothing happens, or I happen to notice the dash lights are on, (like when you first turn the key before you start it). It simply dies.

It usually seems to happen after I take my foot off of the gas to coast after having been accelerating. It happens at any speed so it is not like I had it floored or anything.

At first it would immediately start back up and I could continue to drive without another problem for a few days. However, it started to happen a bit more frequently and the time it took to restart it seemed to get longer and longer. At first it would immediately restart. Now I have to let it sit, (and I assume cool down) for about an hour or so before it will restart. It will start immediately if I spray starting fluid into it, but stalls out as soon as I take my foot off the gas. It seems to run fine until it gets hot.

I've been told it is probably the fuel pump, but I just wanted to get a second, third and fourth opinion before changing it out in case it may be something less expensive. Plus, I'll have to do the repairs myself because of money issues and have no clue what I'm doing. heh

I gave it a full tune-up, changed the fuel filter and the thermostat, but none of that seemed to help. I had the codes checked but none came up at all. I've only owned the truck about 2 months now, but I do like it and want to get it up and running again.

Any help would be greatly appreciated it. Thank you.

C.

 

[gpracer1]

First thing I would check is the Air Idle Control motor IAC.
It is on the passenger side of the TBI throttle body. It has a plug on it and it looks like a big 1 inch nut that sticks out about 2 inches. It goes into the TB and is angled towards the back.

Take it out and clean it with CARB spray and spray into the hole real good too.

 

[ezdaar]

agree, replace the IAC, dont bother cleaning it, Replace it.

Its sticking closed during part throttle, which is causing the stalling when you let off throttle.
The no restart is also caused by the plunger being stuck shut.. No air = no start..

I would also reccomend doing a Fuel pump swap anyways, as older chevys have always had fuel pump issues.. buy OEM pump... dont try and save some cash here as you will just be doing it again in a few months...

Tip for you to increase FP life.. Dont let the fuel get below 1/4 tank. This exposes the FP to air and not fuel, over heating it. causing premature FP failure..

 

[retorq]

If it's not throwing codes then it's more then likely NOT electrical, ie IAC and it's something physical, ie fuel pressure, bad plug wire. Changing the fuel pumps in these isn't fun .. if I were you I would check everything else before I just dropped the tank and replaced it ...

 

[BattelWagun]

I'm leaning towards the IAC, mine had a similar problem where after accelerating pretty quickly the engine would sputter at idle for a few secs(but never die). Cleaning it helped me, so you should try it, but cleaning it doesn't guarantee anything if it's bad it's bad, and you'll need to replace it.

 

[Cerulean]

First off, just let me start by saying thank you for all of the replies and the help. I really do appreciate it. Unfortunately, the truck is at my Sister's house so I'll have to wait until I can make it over there tomorrow to check out the IAC. I'll definitely have a look and let you guys know if I find anything or if cleaning/replacing it helps.

One of you mentioned your vehicle sputtering because of this problem. The strange thing about mine is the truck does nothing at all before stalling. No warning signs. Just dies and I usually don't even notice right away.

Thanks again, and I'll be sure to keep you updated.

 

[Cerulean]

Well, tried cleaning the IAC today. It was pretty gunked up. Cleaned it up really well, and inside the housing too. No change. Replaced it with a new one and still no change. I let the truck run for about 15 minutes and once it warmed up it stalled out and wouldn't restart. I guess it appears to be the fuel pump for sure at this point. No clue what else it could be.

 

[SunlitComet]

if it stalls after a while while just being parked hook up a pressure gauge. If when it shuts off and has no pressure immediately afterward then it is the pump that shut off either mechanically or the oil pressure switch that powers the pump with engine running is flaking out(incorporated with pressure sensor). if when it stalls it is still holding like 40 psi or more some thing shutdown the ignition or fuel injectors are shutting down both controlled by pcm and in the case of ignition also the ignition module.

 

[Cerulean]

I'll see if I can get my hands on a pressure gauge so I can test that out. Thanks for the help.

 

[Trippers99hoe]

I'll see if I can get my hands on a pressure gauge so I can test that out. Thanks for the help.

My 96 chevy PU was doing this and it was the wires where the fuel pump relay plugs in.

Check the fuel pump relay and the connection (where the relay plugs in).
A new relay only cost 10 bucks ,you may be able to swap it with the a/c relay to test this theory.