C4 long crank issue
Thread Starter
4th Gear
Joined: Apr 2026
Posts: 4
Likes: 0
C4 long crank issue
My 1994 c4 has been having long crank issues, at first it was the optispark and i got that replaced ans no issues for like 3 weeks then i went to start it one morning and it took like 3 tries to crank over, it cranks hard and acts like its gonna fire up a couple times but continues to crank until it finally turns over. Ive heard it could be my iac valve sticking so i took it out cleaned it and it started just fine but idled high for about 5 seconds and went back to normal but after starting again 2 hours later it was cranking hard again so im at a loss and obviously could be a fuel issue but even priming the fuel pump before start up and doesnt help at all. Any info or advice would be greatly appreciated
Racer
Joined: Jun 2019
Posts: 276
Likes: 69
From: Florida
I would suggest you check your fuel pressure at the fuel rail valve. The pump will run and prime the rail to about 40psi for 2 seconds when the key is turned to on. There is a check valve in the pump which is supposed to help maintain the pressure for starting the engine. Once it is running the fuel pressure regulator will maintain the pressure. Check the vacuum line going to the regulator and make sure it is dry/no fuel. If it is then the regulator diaphragm is not leaking.
