Hello!

I have been finishing up the long process of putting a new engine into my 83 Trans Am, and it has an Edelbrock Pro Flo 3503 system on it. It's really not new, it's a GM Goodwrench crate motor from the late 90's or early 2000's.

Anyways, I have been able to work out a lot of the difficulties I have come across, but this one is particularly puzzling for me, however I have a possible solution. When I took the car for the first test drive, it was great for the first few minutes. As I drove it more, the engine started to act as if it were being starved of fuel. I would try to move it in gear up to about 2500 rpm and anything more than that would just make it sputter, backfire, and generally just hesitate until I let up off the throttle. The fuel pump would also start making an audible and high pitched whining. What makes me think it is vapor lock is that when I shut the car off for about a minute or so and start it again, the problem with driving and the whining goes away shortly, but comes back. The sending and return fuel lines are both fairly close to the headers, within half an inch. I'm planning to move them more anyways, but I would like to hear anyone else's input on the situation? My only ideas are vapor lock or if something is blocking flow into the fuel pump. If it were blocked, however, I feel like it wouldn't go away after turning it off for a minute. Any feedback? Thanks!

 

Pretty tough to have "vapor lock" (a non-existent problem today, but very common 50 yrs ago, caused by the fuel flashing into vapor in the suction side of the system, between the tank and the pump) when you have EFI (pump is in the tank, line has ~ 40 - 50 psi in it, gasoline has been formulated since the 60s to avoid it as much as possible).

Sounds more like a gas tank venting problem.

Next time it does it, pop the gas cap off and see if it fixes it. If so, look at your charcoal canister, the "UFO", etc.

 

I have tried taking the cap off and letting it run with no luck. The cannister has been gone forever with the line plugged.