My buddy Joe's 94 z28 has been acting up.
Here's the scenario. Starts up and runs fine. Shut it down and try to restart it, most of the time it will restart and run fine. But sometimes it will start stumbling and eventually die.
No codes.
We put a new filter in and changed the pump relay. same thing.
Then we hooked up a fuel pressure guage. Starts up and holds steady at about 36psi. Pulled the vacume line and it jumps up to 42 psi. So we shut it down and tried to restart. Turned the key on, and it goes to 40 psi then start it. Pressure drops steady all the way to zero and of course the car dies. One time the pressure actually came back up just before it died and it ran fine.

So what do you think? Fuel pump? Regulator?
Has anyone experienced this problem before? And what was the outcome. I hate to just throw parts at something without being sure of the problem
Any help is appreciated.Thanks guys.

 

Any Ideas guys?

 

Fuel pump is the problem. Ask him if before the problem, did he run it real low on fuel and then fill it up.

 

Yeah, that's the first thing I asked him. But he has never ran it low on gas.
And I think it only has around 30,000 miles. But it is a 94.
The problem started, when he took it to sears to get a new battery. But I can't see how changing the battery could affect the fuel pump. So I just disregarded the whole battery thing.