1990 C4 having issues....Help
Team Owner
Joined: Jul 2004
Posts: 28,465
Likes: 3,288
From: Hartford WI
I would think that shows up in the IAC counts. It would give you a 0 count and you couldn't adjust the throttle plates close enough to get 30 counts.
Team Owner
Joined: Jul 2004
Posts: 28,465
Likes: 3,288
From: Hartford WI
I would not keep changing parts out, as that gets expensive and you are likely replacing things that are not broken to begin with.
Honestly, if the car runs and if you push down the accelerator and the car dies, it sounds like a fuel feed problem. The inrush of air is leaning the mixture to the point it won't ignite. Could be a lot of things, but I'd focus on fuel pressure first (assuming the vacuum test shows around 20 steadily), around 43 psi with the car running, and even if you rev it a bit. If the pressure is not right, bingo. And if the fuel pressure drops to zero immediately on shutting off the car, you've found the problem. And then have to determine if it is a leaking injector(s) bad fuel regulator or a fuel pump with a bad check valve.
Honestly, if the car runs and if you push down the accelerator and the car dies, it sounds like a fuel feed problem. The inrush of air is leaning the mixture to the point it won't ignite. Could be a lot of things, but I'd focus on fuel pressure first (assuming the vacuum test shows around 20 steadily), around 43 psi with the car running, and even if you rev it a bit. If the pressure is not right, bingo. And if the fuel pressure drops to zero immediately on shutting off the car, you've found the problem. And then have to determine if it is a leaking injector(s) bad fuel regulator or a fuel pump with a bad check valve.
I don't disagree except with the reving part. If you put it under load, you can see better if the pressure can keep up or not. If not, first place I look is the pump.
