I have a 84 z/28 H.O. It now has a 383 stroker with a 770 holley carb. I replaced the gas tank, because of rust. The high performance fuel pump on my stroker is unable to suply enough fuel and the car is going dead on me when ever I drive it for any long (30 minutes or so) length of time. On short trips it runs fine. It hauls major tail. but if I put it on the road for a little longer distance it runs out of gas and goes dead. When I replaced the tank I notices a braket where what looked like an intank fuel pump went. There is not one there now though. Also when I removed the original engine there was a mechanical pump attached to it. It looked like it had been on the car since the factory. Did the car come with two fuel pumps originally? If so could the lack of the in-tank pump be my problem? Even with a high performance mechanical pump? I would really rather not have to pull the tank again. Could I just install a high performance electric pump as well as the mechanical one that I have and expect the problem to be solved? Every time this happens I have to have it towed and every time I think I got it fixed it happens again and I am tired of towing bills. Please help! Any advice would be great.

Thanks a lot guys!

 

Some cars have both an electric in-tank pump, and a block mounted mechanical pump. The stock mechanical pumps aren't exactly high performance, but they'll perform well enough.

Did you replace the strainer sock when you replaced the tank?

 

When I pulled the tank there was no fuel pump in there. Just a bracket where one should have been, and an extra piece of line to the correct length. I have a high performance mechanical on the 383 stroker that's in there now. I thought the new pump would be strong enough to not need the in-tank pump. It runs good most of the time but when I run it for a while it runs out of gas and takes a couple of hours to get gas back in the lines.

 

By piece of line, do you mean a piece of hose? Someone's removed an in-tank pump then.

It would never ever take a couple of hours to get gas back in the lines. A mechanical pump will prime in seconds.

 

Sounds like you've got a vapor lock problem, not an inadequate fuel pump. The stock factory pump had a return line to keep fuel moving through the supply line to reduce the chance of it picking up heat. Most "performance" mechanical pumps don't have the return, I'm guessing yours doesn't. The gas line probably comes close to a heat source, like headers, which only makes the problem worse.

Which tank pick-up were you describing, the one that was in the car, or the one you put back in?

 

Yeah, my return line is capped off. At least I think it is. I have two lines, one slightly larger than the other. I have my fuel line running from the larger line. Is that the right line? The motor was gone when I found the car setting in a field. It had been there since 1999! I have been trying to bring it back for over a year. Something about this car. I just fell for it. I built a 383 stroker for it, just got it from the shop last Friday getting a eaton posey and new axles installed. Fixing the fuel problem is giving me fits! I thought about header heat and wrapped the fuel line in header wrap, put an electric pump back by the tank to go along with the mechanical one. It seems to help, but has not totally fixed the problem. If it is vapor lock, what can I do to solve it? The lines are very close to the headers. I don't think there is room to re-rout the lines. Any ideas? I'm sick of being broke down on the side of the road! This is ford country and mustang drivers love to blow their horns when they pass a broken Z-28 on the side of the road. LOL

 

Yes, that is the supply line.
Running the return line will help some, because it will reduce the time the fuel stays in the heat source area and picking up heat. Shielding the line can help. Rerouting as much as possible is the real solution.

It probably didn't have one from the factory, but if the car has an in-tank electric fuel pump in it, and it isn't working, it's really hard to suck fuel through a dead pump - that will lead to vapor lock.