1990 Running problem
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
1990 Running problem
1990 C4 Corvette. when you tun the key it runs and fires up fine, bu will then die about a second of two later. I have found that I have been able to keep the engine running when I can keep the rpms up around 2000. Anything lower than that, it dies. Could this be a weak fuel pump? In my experience, a fuel pump will either work or not. thoughts?
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
What I have is the opposite, the engine will not idle but will run at higher rpms. No codes or check engine lights either.
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
The fuel pump is powered by the fuel pump relay. There is an oil pressure switch that will power the fuel pump if it sees more than 4 PSI. It is a BACKUP for the fuel pump relay and will NOT "save the engine" by shutting off the fuel pump if the oil pressure is low. You can disconnect the oil pressure switch (I have done this as an experiment to prove the point) and the engine will continue to run just fine.
Team Owner
Joined: Jul 2004
Posts: 28,331
Likes: 3,245
From: Hartford WI
Disassemble the Throttle Body. Remove the IAC housing also. Clean the IAC pintle, housing and the entire TB including the passages. Reinstall with NEW gaskets and reset the IAC using the IAC counts.
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Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX
Internet myth. Totally UNTRUE.
The fuel pump is powered by the fuel pump relay. There is an oil pressure switch that will power the fuel pump if it sees more than 4 PSI. It is a BACKUP for the fuel pump relay and will NOT "save the engine" by shutting off the fuel pump if the oil pressure is low. You can disconnect the oil pressure switch (I have done this as an experiment to prove the point) and the engine will continue to run just fine.
The fuel pump is powered by the fuel pump relay. There is an oil pressure switch that will power the fuel pump if it sees more than 4 PSI. It is a BACKUP for the fuel pump relay and will NOT "save the engine" by shutting off the fuel pump if the oil pressure is low. You can disconnect the oil pressure switch (I have done this as an experiment to prove the point) and the engine will continue to run just fine.
Throttle body has been cleaned in the last six months, but I will try this out after I check fuel pressure to be sure. Just curious, do you have any more detail on resetting the IAC using the counts? Not sure about that one.
Team Owner
Joined: Jul 2004
Posts: 28,331
Likes: 3,245
From: Hartford WI
I get the engine to closed loop operating temp. Shut everything but the engine off and run the scanner and check IAC counts. Assuming the timing is right and there are no leaks, the IAC count should be about 20. If it is more, the IAC is opening up for more air so you need to turn the throttle body adjusting screw in to open the blades to allow more air and less need for the metered "air leak". Rev the motor and see where it settles. If it is less than 20, the engine needs less air so screw out the TB adjusting screw, rev and recheck. After it gets to target, you adjust the TPS based off the scanner reading.
Race Director
Joined: Mar 2015
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I thought this was wrong, made no sense when he posted it.
Throttle body has been cleaned in the last six months, but I will try this out after I check fuel pressure to be sure. Just curious, do you have any more detail on resetting the IAC using the counts? Not sure about that one.
Throttle body has been cleaned in the last six months, but I will try this out after I check fuel pressure to be sure. Just curious, do you have any more detail on resetting the IAC using the counts? Not sure about that one.
Thread Starter
TheCorvetteBen
Joined: Feb 2007
Posts: 4,987
Likes: 144
From: Van Alstyne, TX