fired up the hotrod today for the first time. couple problems i am having. i think it is computer related but maybe fuel. i turn the key on, fuel pump primes to about 30 psi. start the car, it runs and pressure goes up to about 40 psi. then fuel pressure drops off to 0 and car dies when its at about 8 psi. am i missing a wire somewhere that is making the fuel pump shut off? or am i sucking air or something? it will run till i loose fuel pressure thats it. if i prime fuel pump by turning key on it gets up to about 30 and falls stedily down when the fuel pump shuts off. can anyone help me?

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87 z28 bowtie aluminum 420small block dry sump crower lt. wt. knife edged crank oliver lt wt rods brodix track 1's super ram intake hooker long tube headers mufflex 4"exhaust accel dfi art carr 700 r4 3.42 gears ssm sub frame/ladder bars.....other parts on the way ,soon to be finished!! couple more weeks!!!

http://people.ne.mediaone.net/gdm

 

try having someone probe the ground wire for the fuel pump with test light. Make sure it's getting power. Sounds like it may have a bad relay or something. Also, what fuel pump are you running? And how old is it? It could have a bad check valve in it and won't hold pressure. Also, check your regulator, it could be totally shot. If the car sat for a while it might have gone had.

 

car has been sitting for about 2 years with no movement inside a heated shop. the pump i got used 2 years ago, no clue how old it is, but it looks just like the accel pump listed in summit. i tried finding specs on it everwhere could not. i did find out it was a replacement pump out of a jaguar or something like that. the thing has a 1/2" inlet and was used on a road racing vette, so i know it flows fine but did not know about check valve.
if i turn pump on with with return line pinched (regardless or regulator) it should hold pressure right? unless it is the pump that is bad? can i put a one way valve or should i just spend the dough on a new pump?
as i want this thing finished so i can drive it before winter....it has been two years since the start of this project and its time it hauls *** down the road

 

One thing you can try to do is to short the relay contacts on. This way the pump will be on all of the time. This will tell you if the pump is bad or the FPR. If they seem OK, then it's the relay or ECM.

If the pressure remains low with the pump on all of the time, block the return line. If pressure goes up, it's the FPR. If not, it's the pump.

If it's the pump/ECM, replace the relay with another, or monitor the signal from the ECM. It should remain low all the time (I think the ECM grounds the relay, but I may be wrong.)

If the pump is in the tank, it's probably the rubber hose between the pump and the hardlines.

 

The pressure bleeding off is typical of the Accel type pumps. They don't have the 'check ball' so once they are off they can't maintain pressure.

This sounds very similar to what I went through with my car. I freaked the first time I fired mine up and it did damn near the same thing. It sounds to me like the FP is to low. Do you have an adjustable regulator? You don't say one way or the other. If you don't, get one. If you do, start cranking the screw. I really had to play with mine to get the pressure where I wanted it. Now, when I turn the key on the pressure is something different each time while the pumps prime. Once the engine is running the FP is steady and dead on. The only pressure you should worry about is running pressure. What I did when I set mine was pull the coil wire, disable the injectors and have a friend crank the engine over and watch the fuel pressure while I adjusted it. Once I had the FP where I wanted, I hooked everything back up, turned the key, and she purred like a kitten.

You'll have to forget everything you've learned about 'stock' type pumps and just worry about running FP. Mine are nothing at all like the stock type Walbro in-tank that I had.

Chris

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1996 SS Convertible FOR SALE
1989 Formula 6" rod'd 406, Vortech R-trim, Iron Eagle heads, ASSC custom grind cam, Accel ProRam intake, BBK 58mm TB, 72# Siemen injectors, Accel DFI, 200 hp NOS, ASSC custom CAI, Hooker LT's, custom 3" off road pipe, 4" Mufflex, ASSC custom fuel system with 2-870hp Accel(Bosch) pumps(1 mounted in-tank),TH400 conversion, Art Carr torque convertor, 91 Formula front bumper cover, 91 rear decklid wing, 91 GTA taillights, GTAA RAII hood

[This message has been edited by 96BlownSSragtop (edited September 13, 2001).]

 

thanks for all the replies... blown96....just the answer i was lookin for. yes i do have an afpr. i wired my pump to constant 12v. adjusted the regulator and it seemed to hold steady. but when i prime before starting it was all wacky....so, i'll try it again after i get my super ram tapped from the inside,and button up the oil leak. my mind is at ease a bit now, thanks

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87 z28 bowtie aluminum 420small block dry sump crower lt. wt. knife edged crank oliver lt wt rods brodix track 1's super ram intake hooker long tube headers mufflex 4"exhaust accel dfi art carr 700 r4 3.42 gears ssm sub frame/ladder bars.....other parts on the way ,soon to be finished!! couple more weeks!!!

http://people.ne.mediaone.net/gdm

 

Have i have a set of Brodix Track 1's one too and i was just wondering what you did for the holes for the fan switch and the temp sendor

thanks

i've just been thinking about what i have to do

 

You'll have to use holes in the intake or on a T fitting on the heater hose as it comes out of the water pump. Or you could drill and tap into the radiator/head.



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Cody "cyZ28" Young
'84 black on black Z28

355, 5-speed (on the way out. What goes back in, ooohh baby!!)
http://www.geocities.com/mustang_tbird/codypage.html

 

i dont have a fan switch i used a black magic fan with built in thermostat, and my aluminum water pump has a couple of ports and i used one of those for the temp gauge.

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87 z28 bowtie aluminum 420small block dry sump crower lt. wt. knife edged crank oliver lt wt rods brodix track 1's super ram intake hooker long tube headers mufflex 4"exhaust accel dfi art carr 700 r4 3.42 gears ssm sub frame/ladder bars.....other parts on the way ,soon to be finished!! couple more weeks!!!

http://people.ne.mediaone.net/gdm