92 suburban will only idle if you pump it??

[jerhancock84]

My dad has a 92 chevy suburban that won't idle. If you pump the throttle you can get the rpms up but you can't get it to run steady or hold the pedal in any one spot without it cutting out and dying. I have replaced the distributor, plugs and wires, tps, iac, fuel pump relay, fuel filter, map sensor, and rebuilt the tbi. I'm stumped!!!!

 

[Chuzz]

Did you replace the fuel pressure regulator when you rebuilt the tbi? If so, it may be a faulty fuel pump. I'd run a fuel pressure test on it if it were me. If you didn't replace the FPR, you might give that a try, but run a test on it first. If that's not it, I'd check for vacuum leaks around the tbi. If you have none, the I don't know what to tell you. I'm not a mechanic, just a shade tree.

 

[zora]

did you check for any computer codes?

 

[VanGo]

Sounds like a vacuum leqk to me. It's old enough for some dry rot.

 

[jerhancock84]

Ok so there are no computer codes. Tested the egr valve and it was bad so I replaced it. Checked the vacuum lines and didn't find anything there. Replaced the fuel pressure regulator diaphragm when the tbi was cleaned. How exactly does the fuel pressure regulator work and can you test it?

 

[Spriteman]

My understanding is that it maintains a constant fuel pressure with the diaphragm opening and closing based on how much vacuum it's given from the intake.

Basically it's there to make sure the carb/injectors have enough fuel to give to the cylinders.

Any additional fuel is bypassed back to the tank via the fuel return line.

 

[VanGo]

If you pull the vacuum hose off of the FPR and see fuel, it's bad.

 

[bandit2090]

Check your fuel pressure. I had some similar probs with my 94 and it was a disconnected fuel pump.