I put a new fuel pump in the gas tank, and noticed the fuel rail pressure drops of almost immediately when ignition is turned off.
The old pump was holding pressure for a while but would not go above 40 psi, new pump will put out 60 psi no problem.

Is there a some kind of check valve that holds pressure in fuel rail?
The car seems to run fine, and pressure is instantaneous when key is turned on.

Just wondering if I have bad fuel injectors, they are old stock 19lb'ers. ( I need 22# anyway)
Or could I have hooked the return fuel line to the wrong tube back on the gas tank?
there is one steel line that runs to the bottom of the tank and is open, I put 5 gal of gas in the tank and blew lightly through it heard air bubbles, this is the one that I hooked the return fuel to.

what do you think?
thanks
thanks
Scott

souns right for the line hook-up.
- you won't have any pressure if the pump is not on.

mine holds pressure when i turn the key off after the system has been pressurized. it should not bleed down immediately but happen over a span of a few hours.

do you have your return line blocked to get 60 psi? or your regulator cranked down?

I have a holley regulator, cranked down, If I unplug the vac line it will hold 60 psi. old pump would only do about 40.
I needed 52 psi with the 19# injectors, I thought.
I was running very lean. (not good, new motor)

Old pump was missing the sock filter, and an O-ring was blown out of the top of the pump. Almost like it was sucking air or blowing fuel. was getting very hot also.

But which one is it,
I have a pressure gage mounted on the fuel rail, before the new pump it would hole pressure for about an hour, now it bleeds down in about 3 minutes.
But doesn't seem to affect how the car runs.

What holds the pressure in the fuel rail if the return line is just an open tube that runs to the botom of the tank?



thanks
much Scott

the regulator holds the pressure on the return side. the checkball in the new pump should hold the pressure on that side.what size motor are you running? if you are running a 305, the 19 lb injectors are fine. if you have a 350, you need 22 lb injectors. are you using a chip for a 350? the stock injectors might not like the fuel pressure that high and be getting stuck open. not too sure on that one. normal pressure is between 38 and 45 psi.

I built a 350, lt4 hot cam and some head work.
It was a 305.
I just burnt a new chip from a Iroc Z 350, I bought the moates stuff. with the 305 chip it was running very lean.
Yep, I need to change the injectors. But It seems to run better with the high fuel rail pressure.
Its jumping between lean and rich on the turner Pro software.
I guess that's better than really lean. The other day I had one bank, drivers side headers start to turn color on the ceramic coating (bummer) The other side still looks good.
I still haven't drove this thing on the road yet.
Just up and down the street. (sons car, its been about a year, almost ready for him to drive)


How can I tell if the pressure is bleeding at the new fuel pump, or at the fuel regulator?
I could turn the pressure down at the fuel rail, but, she bleeds to zero, fast so Iam thinking its maybe not the injectors???
what do you think?



Also,
If I drive it like this, is this ok?
when key is on, its rock steady pressure at fuel rail. up to 60 psi.

thanks for the help
Scott

with the 350 programming in there, it will think it has 22lb injectors. it will try to open the injectors further than they are built for. with the 305 programming, it will cause the motor to run lean. i definitely wouldn't push the motor till you get bigger injectors in there. that duel pressure will wear those 19lb ones out fast. they weren't designed to run that high.

use a pair of vice grips to clamp the supply line after you have pressurized the system. if the pressure holds, i would look at the fuel pump. if it doesn't, then it is the injectors or the regulator. after pressurizing the system, clamp both the inlet and the return lines. if it doesn't hold, it is the injectors. if it does hold, it is the regulator.