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My First Real Problem

robhauser

Member
Joined
Aug 4, 2005
Messages
22
Location
Richmond, VA
Corvette
1990 Coupe - White on Red
Well…. I have my first real problem with my car… I can’t keep it running.

To preface, I last drove it the day before Thanksgiving and everything was fine. I went to start it today and it started right up as usual, but died within a second and then the starter just cranked… maybe a fuel delivery problem?

I have found that I can start it and keep it running if I depress the accelerator a bit, but it does seem to run rough.

I have also checked the codes and I am getting repetitive 12’s. I am hoping it might be an easily replaced sensor or at the least, I can get it running enough to get it to the shop.

Any insight that anyone can offer would be greatly appreciated.

---
Rob
1990 Coupe
Richmond, VA
 

94conv.

Well-known member
Joined
Jun 16, 2003
Messages
446
Location
Indiana
Corvette
1994 red convertible
Could be alot of things, IAC valve or the computer went caput, faulty TPS. No fuel such as pressure or the pump but if it runs with the accelorator..try unplugging the TPS and starting it. IAC usually just concerns Idle, idling rough and such. Mine sat for a few months then the computer went out, it was sending erratic signals to the injectors.Start at the TPS, just my .02. I have some manuals that I can try and research if no one else has any ideas.
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,521
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
IAC valve's My guess!! If it's stuck it can cause a vacuum problem and will run rough and not Idle worth a darn!!!! These cars are bad for it after setting awhile!!!Changed allot of them!!:upthumbs
 

robhauser

Member
Joined
Aug 4, 2005
Messages
22
Location
Richmond, VA
Corvette
1990 Coupe - White on Red
Thank you for the responses. I unplugged the TPS and there was really no effect. If anything, it might had run a split second longer before shutting off, but it still not idle. I will take a look at the IAC valve after work today. Is there a way I can test the functionality of that?

Also, I noticed another odd behavior. After I try to start it and then walk back up to the engine compartment, I can hear a very faint whistle near the fuel rail. I will also try to track the location of the sound more accuratly. It sounds like either a pressurization or a possible leak of pressure somewhere? It only last a few seconds.

Thanks again,
Rob
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,521
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
Thank you for the responses. I unplugged the TPS and there was really no effect. If anything, it might had run a split second longer before shutting off, but it still not idle. I will take a look at the IAC valve after work today. Is there a way I can test the functionality of that?

Also, I noticed another odd behavior. After I try to start it and then walk back up to the engine compartment, I can hear a very faint whistle near the fuel rail. I will also try to track the location of the sound more accuratly. It sounds like either a pressurization or a possible leak of pressure somewhere? It only last a few seconds.

Thanks again,
Rob
You've got a Vacuum Leak!! Check All the Vacuum lines and Fittings around Intake!!That will darn sure make it not Idle and Run Rough!!!:upthumbs
 

robhauser

Member
Joined
Aug 4, 2005
Messages
22
Location
Richmond, VA
Corvette
1990 Coupe - White on Red
Ah... the dreaded vacuum leak. It looks like I have my work cut out for me. Do you happen to know if there might be a diagram of the vacuum lines posted anywhere?

Thanks again,
Rob
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
Check this

(Also, I noticed another odd behavior. After I try to start it and then walk back up to the engine compartment, I can hear a very faint whistle near the fuel rail. I will also try to track the location of the sound more accuratly. It sounds like either a pressurization or a possible leak of pressure somewhere? It only last a few seconds.)


A whistle near the fuel rail may be a vacumm leak. Check the right side of the engine for this vacuum valve.

http://static.flickr.com/105/290560320_79fb23d3ab_m.jpg

http://static.flickr.com/107/290550589_854bc14d70_m.jpg



Good luck with your search and let us know what you find out.:beer
 

robhauser

Member
Joined
Aug 4, 2005
Messages
22
Location
Richmond, VA
Corvette
1990 Coupe - White on Red
OK - the very faint whine after the car turns off appears to be from the brake master cylinder and it sounds like it is internal to the mechanism. I do not beleive it is related to my problem. So next is to check the IAC valve. Is there a way to test this to be sure it is the failed component?

Many, many thanks to everyone!!
 

robhauser

Member
Joined
Aug 4, 2005
Messages
22
Location
Richmond, VA
Corvette
1990 Coupe - White on Red
Interesting development... I removed the air intake from the throttle body and it started right up! I have checked for any type of blockage and there is none and the filter has only a few hundred miles on it and is very clean. When it is running, the exhaust smells like it is running a bit rich. Does this sound like an IAC failure?
 

John Robinson

Gone but not forgotten
Joined
May 3, 2005
Messages
1,555
Location
Muncie, Indiana
Corvette
1993 Polo Green Coupe
Check the TPS

Check your TPS if the car smells rich. The TPS tells the ECM how much fuel to put through the injectors based on the position of the throttle butterfly. When you remove the air intake you are leaning the mixture out so the car runs better. The TPS has specific voltage values you can check and if they are not present then it is bad. Perhaps you can get those values with a search. My guess is that your problem is not a catastrophic problem.
 

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