I just finished completely R&Ring the fuel system on my Coronet. New tank, pickup, fuel lines, pump, filter and rebuilt and deep cleaned the carb (a Street Avenger 875)

Problem is Im getting terribly low fuel pressure. I dont have a psi guage but when you get on it, the car stumbles and sputters and its not pulling enough vacuum to even fill up the (see-thru) fuel filter. It idles just fine and if I feather the throttle enough it will pull enough fuel through. But when its running, its just spurting through the filter. I pulled the rechecked the pump to make sure it was sitting on the pushrod correctly and it was OK. I also checked all the fuel lines. I richened up the mixture as much I could to see if that would help with fuel delivery and it didnt really make any difference.

The pump is a NAPA replacement part for a Hemi, which I figured would be substantial enough to feed my 875.

Could be a bad fuel pump rod the new ones are soft and mushroom that or you got a bad fuel pump.

vac leak or accel pump prob

Is the tank vented through the cap?

can you put the old pump back on and see if it can draw fuel? it's possible the new pickup is constricted. is the lenght of the fuel pump rod the same as the old one? is the reach of the fuel pump arm and travel distance the same?

check fuel pump pressure and volumn at idle and 2500 rpm.

Some of the aftermarket sock filters that slide onto the fuel pick-up inside the tank go on to far. That blocks the end of the pick-up because it is up against the inside of the sock. If you find that this is your trouble just cut the end of your pick-up tube off at a 45° angle.

Crack the gas cap loose to make sure the tank and/or the cap is breathing properly. A sealed tank will lead to no fuel pressure, especially when using the stock fuel pump. It may run okay on a cold start, then get progressivly worse fuel pressure as vacuum builds in the tank.

thanks for the replies guys, much appreciated

It was too cold to do anything on the car today.

the tank is vented through a tube at the front and not the cap (its a 1968 Coronet with a pre-EEC tank) Im wondering since I havent filled it with a full tank of gas yet (only about 5 gallons to get it running) would that have anything to do with pressure build up inside the tank? Ive replaced tanks before and never had a fuel psi problem.

I think I'll try and run it without the gas cap and see what happens. I just feel like the problem is in the tank.

Ive tried 2 other pumps on it-a stock 440 pump and a Holley HP one and Im still not getting the psi I need.

How about the power valve or accelerator pump?

check that pickup for good flow................i think you are on the right track

Can you temporarily run the car off a jerry can connected to the fuel pump?

Might be able to trace it by eliminating the rest of the system.