Car idle problem
Thread Starter
Racer
Joined: Apr 2001
Posts: 429
Likes: 11
From: Orlando, FL
Car idle problem
My dad bought my car last week and of course it starts surging at idle today and died. Everytime he started it, it would stumble a little then die. Finally he got to a gas station to put more gas in and it runs ok to go down the freeway but was running rough below 2k. He stopped about 15 miles later and when he went to start it again it wouldn't run. There were no problems up to this point.
Any ideas? I was thinking bad fuel or something. I am going to change the fuel filter anyway but was wondering if there was something else.
Any ideas? I was thinking bad fuel or something. I am going to change the fuel filter anyway but was wondering if there was something else.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Need to check fuel pressure at the schraeder valve on the fuel rail. Is this a '89 or 92?
Last edited by BADDUCK; Feb 12, 2007 at 10:21 PM.
Le Mans Master
Joined: Nov 2002
Posts: 7,179
Likes: 2
From: Charlotte, NC
Yep this is an easy thing to do, but as someone mentioned you need to check the fuel pressure & volume. I'm going to GUESS you have a possibly fuel issue.. I would check for vaccum leaks as well, as I'm not sure what year vette you have I would say if it has a MAF sensor make sure there are no air leaks after the MAF.
Good Luck!
-=Rick
Good Luck!
-=Rick
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
More than likely is a fuel delivery issue as well. I only suggested to clean the throttle body and idle air control motor as both can cause idle problems along with vacuum leaks, as we know.
It would not hurt to attach a fuel pressure gauge to the schrader valve, turn the key on and note the fuel pressure. Start the engine and note fuel pressure at idle. Go for a drive with the gauge attached and note any changes especially when the problem occurs. Stop, turn the engine off and see what the fuel pressure does. If the pressure leaks down quickly it could be caused from injectors, FPR diaphram, plusator, check vavle, lines, line connections. The fuel filter probably needs replacing.
It would not hurt to attach a fuel pressure gauge to the schrader valve, turn the key on and note the fuel pressure. Start the engine and note fuel pressure at idle. Go for a drive with the gauge attached and note any changes especially when the problem occurs. Stop, turn the engine off and see what the fuel pressure does. If the pressure leaks down quickly it could be caused from injectors, FPR diaphram, plusator, check vavle, lines, line connections. The fuel filter probably needs replacing.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Thread Starter
Racer
Joined: Apr 2001
Posts: 429
Likes: 11
From: Orlando, FL
Sorry it's the '92 (no MAF), my dad just had it flatbedded to the Chevy dealer and said he would just have them take a look at it. If they don't figure it out then I'll try some of the above but I think they will get it done. I will post what happened after they call back.
Is there a schreader valve on a 92?
Jeff
Is there a schreader valve on a 92?
Jeff
Must have hauled to Searcy.
Thread Starter
Racer
Joined: Apr 2001
Posts: 429
Likes: 11
From: Orlando, FL
Heck no, they don't even have a used car guy here. It died on him in Cabot and they hauled it to Gwatney in Jax. I still haven't heard for them, I guess it hasn't made it in yet. I like Orr there in Searcy though but my insurance only tows to the nearest dealer or somewhat close as there is Ray Chevrolet in Cabot.
Jeff
Jeff
Thread Starter
Racer
Joined: Apr 2001
Posts: 429
Likes: 11
From: Orlando, FL
Well, the Chevy dealer said they couldn't find anything wrong. It started up and they were driving it around. I figure this means the filter was blocked and the sitting allowed the blockage to settle. We are going to change the filter and keep in eye on it.
Le Mans Master
Joined: Dec 2003
Posts: 7,457
Likes: 144
From: NC
Le Mans Master
Joined: May 2005
Posts: 5,214
Likes: 65
From: Queensland, AUSTRALIA
Does it stumble at all when you try and accelerate? Will it pull hard at higher RPM?? Are all the plug leads attached firmly at both ends?
First step is change the fuel filter, which you say youre going to do, Next step is to pull the fuel pump up and have a look at the condition of the filter sock on the pickup. Next step is to pull the vac line off the fuel pressure reg and make sure its not full of fuel (as in the diaphram split in the fuel pressure reg allowing fuel to be sucked in through the vac line), this could cause it run rough at idle under 2,000rpm, and may also cause it to be hard to start (however unlikely it may be).
I dont think this will fix it cause in his first post he states that is was running rough under 2,000rpm. But it certainly cant hurt to clean it anyway!!!
If Techron is some kind of additive to clean fuel injection systems then do this
Although its a 92 with no MAF, this is an absolutely disasterous sugestion in any case. I hope no one with a MAF equiped car ever thinks that is good idea.
First step is change the fuel filter, which you say youre going to do,
Next step is to pull the fuel pump up and have a look at the condition of the filter sock on the pickup. Next step is to pull the vac line off the fuel pressure reg and make sure its not full of fuel (as in the diaphram split in the fuel pressure reg allowing fuel to be sucked in through the vac line), this could cause it run rough at idle under 2,000rpm, and may also cause it to be hard to start (however unlikely it may be).I dont think this will fix it cause in his first post he states that is was running rough under 2,000rpm. But it certainly cant hurt to clean it anyway!!!
If Techron is some kind of additive to clean fuel injection systems then do this
Although its a 92 with no MAF, this is an absolutely disasterous sugestion in any case. I hope no one with a MAF equiped car ever thinks that is good idea.
Thread Starter
Racer
Joined: Apr 2001
Posts: 429
Likes: 11
From: Orlando, FL
Well, dealer called today, they said the opti is going bad. They also said I need fuel injector service, transmission service, tuneup, belt, new hoses and the opti unit. They wanted $2,800. Not going to happen. They are going to charge me $100 for looking at it (which is pretty good as I didn't have to put forth any effort) and the $75 for the tow bill (which my insurance will cover). So I'm going to buy a opti unit this weekend as well as the hoses, belt and fluids. Can do this myself easily enough except for the injector service but I think that isn't needed at the moment. I am still replacing the fuel filter while under the car.
My dad just bought the car from me so I'm going to get everything and I guess we have a father/son project coming up.
I'll have to enlist my brother too.
Jeff
My dad just bought the car from me so I'm going to get everything and I guess we have a father/son project coming up.
I'll have to enlist my brother too.Jeff
Thread Starter
Racer
Joined: Apr 2001
Posts: 429
Likes: 11
From: Orlando, FL
Oh and to check the fuel pump they put a pump directly on the fuel manifold to make sure it wasn't at fault. I wish that was it, those things are a cinch to change on a vette. You could ****** one of those things out in a parking lot in 10 min or less and not even unlock the car. Lucky they aren't something a thief would want.
Le Mans Master
Joined: Dec 2003
Posts: 7,457
Likes: 144
From: NC
Sadly, it took the guys at the dealership where I had it towed only a few hours to get it back together. I never could get that damn dampner off. Man it makes me mad even thinking about that car.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
"Although its a 92 with no MAF, this is an absolutely disasterous sugestion in any case. I hope no one with a MAF equiped car ever thinks that is good idea."
Since when??? Disconnecting the harness at the MAF and letting it run on backup is a basic diagnostic test in every Service Manual, particularly if you suspect a rich or lean condition (or have a scanner and that's what it's showing). It will also rule out the MAF for a host of driveability issues. I don't know of any "disaster" that comes from this. Hell you can drive it with it disconnected if you want to - it isn't going to perform very well, but it isn't going to break anything either. The failure rate of the GM MAF is legendary (though it's far better in the C4 than some of the others). Electronic fuel injection is designed so that it continues to run when information sensors quit working and if one is sending garbage, well it going to run like crap. Either scan it or take it out of the picture and see what happens.
Since when??? Disconnecting the harness at the MAF and letting it run on backup is a basic diagnostic test in every Service Manual, particularly if you suspect a rich or lean condition (or have a scanner and that's what it's showing). It will also rule out the MAF for a host of driveability issues. I don't know of any "disaster" that comes from this. Hell you can drive it with it disconnected if you want to - it isn't going to perform very well, but it isn't going to break anything either. The failure rate of the GM MAF is legendary (though it's far better in the C4 than some of the others). Electronic fuel injection is designed so that it continues to run when information sensors quit working and if one is sending garbage, well it going to run like crap. Either scan it or take it out of the picture and see what happens.