Howdy- I replaced the fuel pump in my Trans Am and it starts and runs great when cold. I drove it 90 miles this weekend to visit my girl at her school and it was fine. I parked it overnight and it started fine the next day. However, once it warms up the engine gets an uneven idle and threatens to kill and if I shut it off and start it again, it won't idle at all without nursing the gas. Once it gets up to highway speed it seems to relax again and function as normal. No hesitation what so ever. Am wondering if my new pump is faulty or if I installed it incorrectly or my car is trying to make me look like a d-bag. Any info would be appreciated. Also- my reverse seems to take a second to catch once engaged. The fluid level is fine and it looks clean- did not want to pull the pan unless totally necessary as the forward gears are good. Could the transmission maybe be causing the engine to act up?

 

Almost sounds like you have a problem with the coolant temp sensor not telling the PCM the engine has warmed up, causing it to run too rich when hot.

What was the problem that lead you to replace the fuel pump? Was the engine exhibiting the problem you describe above before you replaced the pump? Have you checked the fuel pressure with the new pump?

You should set up a "Signature" to include basic info about your car - year, model, engine, trans and any major mods. We can guess from your screen name that its an LT1. Setting up a "Signature" with the basic info eliminates all doubt.

I would also post the tranny question in the "Drivetrain" forum. Better chance of it being seen.

 

Thanks for the info-

When I bought the car, it had a very bad hesitation to start. I found that if I primed the pump by turning key on and not cranking, it would start fine. I worked my way through the fuel system with (in this order) injector cleaner, fuel filter, pressure regulator, fuel pump. I had the rails tested for pressure before installing the new pump and the tech said there was a low pressure issue. I am guessing this caused the bad starting and why priming the pump to build pressure worked. Its starting and firing fine now if started after sitting overnight. I even drove it an hour and a half to see my girl at college and had no issues the whole way. If I shut the car off, whether I drive for an hour or for 20 minutes, it does not want to maintain an idle on its own without me nursing the gas pedal.