I've got a 88 GTA 350 with a mech. pump fed carb. my problem is that while it is running you can see the gas in the glass fuel filter slowly getting less and less. It acts as if the pump can't keep up. after about 4 min. the car will die. wait a few minutes, it starts right up. and the fuel filter fills back up and the prossess starts all over again. the in tank pump is still in place. Is that what is doing it? I have heard that you are suposed to remove them and replace them with a piece of hose. but noone ever says why. wont the mechanical pump suck threw it?

 

Jam the end of a straw against the bottom of a glass of water and try drinking.

If the in-tank pump still runs, you can use it in conjunction with the mechanical pump.

 

do i need a regulator between the intank pump and the mech? if I go with the mech only can I just cap off the return

 

No, the mechanical pump has an internal regulator. Don't cap off the return.

 

with the return uncaped fuel trickels out....

 

I would guess that since the car is an '88 and has had a mechanical pump added to it, that the pump that was put on was a "normal" input/output only pump. The "return" the originator was talking about was the return line on the car.

If that is the case, you need a return-style regulator after the mechanical pump.

Or, put on a "normal" 3rd-gen style mechanical pump that has the return port, with a 5/16" line connecting the pump return port to the car's return line.

 

should I put a FPR with a return on it just to send that gas back to the tank? why would gas come up and out of the return in the first place?

 

Yes, you should. The in-tank electric pump needs a constant flow of fuel to keep it cool. If you dead-head it, it will burn out.

The return line goes to the bottom of the tank - it doesn't just dump the fuel back in the top of the tank. So, it can siphon out if not closed.

 

could i just hook the mech. pump to the return and suck through that?

 

I've heard of it being done. Two problems:

1) It's a 5/16" line instead of 3/8". You've already got fuel starvation issues.
2) There isn't a pick-up screen on it, so the pump will be vulnerable. Putting a filter on the suction side of a pump isn't a good idea.

 

about where at in the trunk do I need to cut the hole?

 

UPDATE I have cut the hole, pulled the sending unit out, replaced the pump with a pipe, patched it all up, and wouldn't you know...The thing runs great!!!