ok,

91 z28 vortec crate 350 w/stock tpi system. well almost, holley 52mm throttle body and an AFPR.

at the fuel rail....27psi tops. this is the 3rd AFPR i have installed, this is the second fuel filter (yes it is facing the right way), the second fuel pump (man this is getting expensive) and it's a walbro/holley 190 lph now, second set of injectors, i can find no kinks in any fuel line.

if you loosen the fuel line under the hood you get a couple of ounces of fuel out. none comes out the return line.


when you turn the key on it goes up to about 25psi and drops back down. will hold if you kink the fuel hose so the injectors are holding.

with car running (yes the vacum line is off) no matter how far in you adjust it only 27psi. you can adjust it out and the pressure will drop but 27 is all on the up side.

suggestions will be appreciated!!

i am about to tear it all down again but would like some input before i do.

 

Couple of thoughts,

Have you checked the fuel pump wiring to ensure you have good voltage, and a good ground?

When you replaced the pump, did you reuse the stock pulsator? Were the short rubber hose pieces in the tank in good condition, and securely clamped? A leak in any of those would cause a loss of pressure.

Have you verified that your pressure gauge is accurate?

Other than that, the only thing I can think of is some debris blocking one of the feed lines. You could disconnect the ends and blast them out with compressed air. However, I wouldn't recommend that for the rearmost line w/o dropping the tank and disconnecting the fuel pump first, so as not to risk blowing any crap back into the pump. Also, if you can rig up a pressure gauge at the fuel filter connection, you could quickly determine if the problem is further forward, or aft, of that point.

Good luck,

 

thanks Dave,

i had the pump installed at a garage. it was ALL supposed to be checked but i will go back over it again to make sure.

if there was a problem in the tank would i still get that much fuel when priming the pump?

i have checked it with 2 pressure guages and they are almost identical. maybe a pound diffence. there was no change in idle when trying to up the pressure either. if i took it down to far then it would change but on the up side after 27 no matter how much more you adust it no change in idle at all.

with all that has been done i suspect a blockage somewhere too.

one more thing.....when i checked my email it had 37 messages in my in box telling me they had all replied to this posting. then when i get here only yours, hmmmm maybe the car problem is contagious!!

 

When you shut off the key and the pump stops, will it hold pressure? I'd guess the pulsator in the tank is shot. This is a diaphragm just above the pump that is supposed to smooth out the flow. Or maybe the wrong pump? A TBI pump is a lower pressure type pump.

 

OK,

guy at garge said he elimnated the pulsator. i thought is was just to "smooth" out fuel flow so how could it prevent fuel pressure from reaching correct reading? i know it will not hold pressure when it primes without the pulsator but should it effect pressure while running?

pump is a holley/walbro 190 lph pump. i even called holley after i recieved it and read the number and verified what it was. that's how paraniod i am at this point!!

 

If the pulsator had a pinhole leak...

 

If the pulsator is gone, no problem with that then. At this point I'm guessing a cracked/broke fuel line inside the tank, or something of this nature. Do you have a hole cut for pump access or are you dropping the tank? Real pain if so, but try to check the voltage to the pump at the tank, and look for a plug in connector at the top inside of the tank for the pump wires.

 

YOUR GONNA LOVE THIS.......

well, after hours and hours and hours of pulling, checking, and replacing parts........

after hundreds and hundreds of dollars.........

finally gave up and took it to the chevy place. after $482 they got it fixed.

after 3 days of looking they called and asked if they could drop the tank. i said 'sure' but i just had a new holley high volumn fuel pump put in.

i was so paranoid i even called holley and read them the number off the box and they verified i had the right pump before it was installed.

so they drop the tank and call me. seems they ran the number ON THE PUMP and after talking with holley it is a high volumn pump for a friggin dodge neon.

SEEMS SOME ONE AT HOLLEY PUT THE WRONG PUMP IN THE BOX.

anyway, i bought another pump (NOT A HOLLEY) and they installed it. car runs great.

called thunder racing and they will send it back to holley after i send it to them.

MAY YOU ALL BE SPARED FROM THE KIND OF DUMBA S S mistake.

thanks for the suggestions.