with the other posts, and run a diagnostic test on the fuel system. start with the basics - sounds like it's either injectors or FPR. if you need injectors help, call Jon at FIC.
1990 C4 Problem
Thread Starter
1st Gear
Joined: Sep 2011
Posts: 1
Likes: 0
1990 C4 Problem
Hi all im new to the forums
so i made this account for my dad because we are having trouble with our 1990 corvette
im not sure if this has been answered on the forums so ill just explain what it is doing
When the vette has been sitting over night and you first turn it on it runs kinda rich probably idles around 2200rpms so after a little while it starts to cough and you kinda have to help it stay running but then it just starts dumping gas and heats up like crazy (pipes turn red/ lots of smoke from extra gas burning) and then it basically floods itself.
Any advice would be great!, we have a general idea of what it might be but we came here to see if anybody else has had this problem
Thanks, Reiss
so i made this account for my dad because we are having trouble with our 1990 corvette
im not sure if this has been answered on the forums so ill just explain what it is doing
When the vette has been sitting over night and you first turn it on it runs kinda rich probably idles around 2200rpms so after a little while it starts to cough and you kinda have to help it stay running but then it just starts dumping gas and heats up like crazy (pipes turn red/ lots of smoke from extra gas burning) and then it basically floods itself.
Any advice would be great!, we have a general idea of what it might be but we came here to see if anybody else has had this problem
Thanks, Reiss
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You likely have leaking injector/s. Turn on the ign to run for more than 2 seconds and measure the fuel pressure, it should be 35-42 psi and turn off the ignition. Fuel pressure should hold up or have only a few psi leakdown in 30 minutes. If you lose pressure rapidly, then either you have leaky injector/s or the fuel pressure regulator or its check valve are defective. Since you have a very rich condition, it must be the injectors.
Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
What JFB said.
+
Remove the vacuum hose from the fuel pressure regulator & check for raw fuel in the hose. If the FPR diaphragm is bad fuel will pump into the intake manifold.
+
Remove the vacuum hose from the fuel pressure regulator & check for raw fuel in the hose. If the FPR diaphragm is bad fuel will pump into the intake manifold.
Team Owner
Joined: Jul 2004
Posts: 28,422
Likes: 3,275
From: Hartford WI
Melting Slicks
Joined: Dec 2004
Posts: 2,473
Likes: 732
I also have a 1990. About 2 years ago, I had to replace the fuel injectors. Got them at a good price at the Fuel Injection Connection. My engine would run, but once it warmed up, two cylinders would stop firing because of bad injectors. I took it to a mechanic that I use for complicated problems, and my car's computer told his computer which two cylinders were not firing. Of course, this made the engine run rough, but it didn't put out black smoke or overheat or cut off.
About 7 years ago, the computer was going bad and I had to replace it. The malfunctioning computer would cause the engine to put out black smoke. Sometimes, the SES light came on and I knew I had 20 seconds to find a safe place to pull off the road. Within 20 seconds, the engine would stall out and would not start up again for 10 to 20 minutes. Eventually, it wouldn't start until it had sat overnight. A remanufactured computer made it run well again.
About 7 years ago, the computer was going bad and I had to replace it. The malfunctioning computer would cause the engine to put out black smoke. Sometimes, the SES light came on and I knew I had 20 seconds to find a safe place to pull off the road. Within 20 seconds, the engine would stall out and would not start up again for 10 to 20 minutes. Eventually, it wouldn't start until it had sat overnight. A remanufactured computer made it run well again.
Last edited by Photomania; Sep 20, 2011 at 10:25 PM. Reason: correct mistake
Team Owner
Joined: Jul 2004
Posts: 28,422
Likes: 3,275
From: Hartford WI
How does it tell that? The L98 is batch fired and there is no cylinder contribution test, is there?
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