2000 Gmc Sierra Stalling at Idle

[chefczar1]

I have done a complete tune up, changed out #6 and #1 coil. still stalls. replaced fuel filter and pcv valve. Others have told me it could be a bad valve bad spring. wiring problems or PCM. WHen doing the testing the book calls for a crankshaft sensor. Judging from some other blogs that hasn't worked either. is there anyone who has had this problem and fixed it?

[maxwedge]

Welcome to AF, stalls when? How long, if at all, does it take to restart? lots of info missing here.

[chefczar1]

The longer or hotter the car gets the worse and more frequent the stalling is. Not too much problems restarting, however the longer the car runs the harder it is to start, but it always restarts. I read a reply you did for a guy called Deuce? in 07 with the same exact problems. He had replaced basicallyt everything but still had the problems. I want to avoid those problems.

Stalls only when truck is at Idle. The truck actually loses voltage the longer It runs. Alternator,starter, battery checked out fine

[Schrade]

Any loping at idle?

Done fuel pressure testing?

[chefczar1]

yes there is loping at idle. Thanks I will check fuel pressure. let you know what happens later in the week.

[montytx]

This must be a known issue. My truck has been rough in idle for 3-4 years. I have to rev it in winter to keep it running. But once I get the truck on the road and run it, it is fine. When I changed out my plugs that helped it out quite a bit. Seemed to reduce the issue by about 1/3.

[chefczar1]

Thanks for the REPLY. My Sierra just started running rough around 100,000 miles. It wound up being an issue with the ignition wiring. I also changed out the IAC. I'll post if the problem pursists or makes it better. I had changed out the plugs and wires aso and it didn't help the problem at all.

[Schrade]

Originally Posted by chefczar1

yes there is loping at idle. Thanks I will check fuel pressure. let you know what happens later in the week.

LOPING! Case closed (pretty sure).

Vacuum leak.

Loping idle is vacuum leak. 30 year old lawnmower, or a new car on the lot. If it sucks air where it ain't supposed to, it lopes.

Brick on pedal, block TB arm, anything to get a STEADY idle. 1200rpms or so... Feed starting fluid spray, A LITTLE AT A TIME, EVERYWHERE. Rev increase is the leak.

In a tough spot to pinpoint? Light a book of matches, blow it out while the heads are burnin', and feed the smoke to the leak.

Post back!

[yamaha4556]

vacuum leak

also check the idle air control valve for excessive carbon build up. This basically lets more air into the tb at idle when its cold out. if its stuck open it would let more air into the engine when it shouldnt be. Cleaning it might help.

[Kelsey92504]

I have a 2000 sierra and mine would do the same thing. Stalling at idle espically when cold. I changed plugs, wires, fuel filter, pcv valve, everything to do with a tune up and I got nothing.Then I cleaned the mass air flow sensor, iac and thorttle body and it finally quit.