fuel flow help!

[spoolinawdtsi]

87 mustang. fuel cell in spare tire department of trunk. 5/8 fuel line runs along frame into log style filter middle of car all the way to mechanical fuel pump on block.
Fuel pump is a performance products high volume piston pump. 5/8 in 1/2 out.
After playing around with car keeps losing fuel pressure an dying..
i checked filter it flows fine.
pump works fine.
so i check the lines. fuel will flow through it but only after unhooked an lying on the floor.
Questions is! does these piston style race pumps suck fuel from cell an pressurize carb or does it rely on gravity fed fuel?
Does this pump need a electric fuel pump mounted at the cell to feed it?

[joe2412]

your pump is the problem throw it out and get a mechanical race pump and regulator your fuel delivery to the pump sounds right don't change it gvood luck joe g

[DRTRCR22]

Make sure you have a lot of fuel cell breathing with a good roll-over vent line, as big or bigger than your feed line. You cannot ever have any negative pressure in your cell or it will stop flowing. It is even worse with a belt drive pump.
I agree with Joe, sell the piston pump and install a good diaphram pump... it will do everything you will ever need. I have run a good diaphram pump with as small as -8 (1/2") feed line from the cell to a 650hp methanol dirt modified big motor, and a regulated -6 (3/8") bypass return line back to the cell, and never had a problem with enough fuel flow. I have seen numerous times a vaccuum lock on poorly vented fuel cells.
The piston pump is just another gimmick that just does not work for most applications... JMHO... Jim

[RonOwensRacing]

I don't know about the pump you have but i have sold and run the race pump .
We have a lot of dirt racers and drag racers here running the race pump and they work great .
But like said before make sure your cell is vented well it will stop the flow.