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-   -   Lost fuel pressure! (http://www.clubcobra.com/forums/shop-talk/83193-lost-fuel-pressure.html)

dlampe 10-21-2007 05:35 PM
Lost fuel pressure!
 
My fuel pump is a holley red pump and it will no longer pumps fuel. When I disconnect the "out" Line to the carbs and blow through it, I can hear the fuel bubbling in the tank. It feels like there is air coming out when the pump is running. It just won't pick up any fuel. I have plenty of fuel in the tank. Any ideas? Do you need more information?

wtm442 10-21-2007 05:59 PM
1) Defective pump :LOL:
2) Break in the line coming from the tank - do you have gas line coming out of the top of the tank? I assume yes. If so, the break in the line is above the fuel level.
3) Is there a fuel filter (screen or small sock) on the fuel pickup in the tank? It might be clogged. My 442 had that problem many years ago. What a PITA. Took a long time to find and fix the problem because it ran OK except at WOT. Probably not this per your explanation that "it feels like there is air coming out ...".
3) Other problem :LOL: :LOL: :LOL:

Naumoff 10-21-2007 07:36 PM
Dean How is the pick up installed into the fuel tank? Is it dropping in from the top or tapped into the bottom of the tank?

If the line drops in the top of the tank make sure that the line on the gas tank side of the pump has no leaks or it will suck air just like a straw with a hole in it.

Rick Parker 10-21-2007 07:43 PM
If the break in the line inside the tank was above the fuel level it wouldn't bubble when he blew into the line from the carbs, right. Suggest looking at the pump, they are notorious for short service life and much has been discussed by others previously, regarding that very subject.

Naumoff 10-21-2007 07:54 PM
Quote:
Originally Posted by Rick Parker
If the break in the line inside the tank was above the fuel level it wouldn't bubble when he blew into the line from the carbs, right. Suggest looking at the pump, they are notorious for short service life and much has been discussed by others previously, regarding that very subject.
Not necessarily. Blowing you are pushing down on the fuel with help from atmospheric pressure, when sucking the atmospheric pressure is working against.

The pump could be bad but I would check the line first.

dlampe 10-21-2007 08:00 PM
I took the pump apart to find a massive amount of trash in front of the fine brass screen inside the tank. Easily enough to restrict flow. I cleaned it out and put it back on. It doesn't seem to be picking up fuel even after I cleaned the trash out. It feels like the pump is turning. Should I try to prime the pump? I didn't think that was necessary but I don't know. The integrity of the line is intact including the pick up.

Naumoff 10-21-2007 08:10 PM
Deane,
I would take the pump off and put some hoses on it and see if it pumps fuel out of a gas can. If it won't pump then you know the pump is trash.

You shouldn't have to prime the pump.

JAM1775 11-06-2007 03:33 PM
I chased a low and at times low fluctuating fuel pressure problem for over a week. I replaced the Holley pump ( hey it was due anyway!), regulator which came with the pump, blew out the lines...crazy even after dropping the tank and inspecting the pick up line. Second time around I isolated the problem to the tank working backwards using a portable psi gauge . This time when I pulled the tank down I real;ly scrutinized the fuel pick up line and suddenly found a hairline crack 3/4 up in the pick up line . That was my problem all along.

Igofastr 11-06-2007 04:03 PM
My first Holley Red lasted 800 miles.

I'd start by replacing the pump (~$100). If it turns out to not fix to problem, you'll already have a replacement for the time when it is. :)

WildBill3 11-06-2007 04:16 PM
Dean we used to run the holley pumps on our I70 racer we had a problem with the spring loaded bypass plungers sticking man we chased this problem for awhile.I think the Aeromotive are a higher quality pump from what all the racers around here say they wont run the Holley stuff anymore .We still run a standard Holley electric pump on the street car but it doesnt sit much any moisture in the fuel while sitting for extended time seemed agervate my pumps,hope this helps...WB3

RedSabre 11-06-2007 04:22 PM
Check your electrical. I had a similar problem on my Bosch pump and found out it was not getting power which turned out to be a faulty connection. I would be sure you have a good ground and power to the pump before tearing anything out or open.

Mike

scootter 11-06-2007 05:12 PM
Was the screen in the pump plugged, or the pickup in the tank? If either had crap in it, you should check the other. I have the black Holley the has a screen inside the pump.
Scott

Roscoe 11-07-2007 07:32 AM
After years of playing with Holley fuel pumps I finally got wise and THREW THEM AWAY!

I replaced the pump with an Aeroquip one and pressure reg and never looked back.

Roscoe

undy 11-07-2007 09:55 AM
Any electric pump will last longer with a plumbed fuel return system (bypass/return style fuel regulator too). The return system keeps the pump flowing and reduces pump cavitation and internal erosion under light engine loads. I re-plumbed my Lone Star with a "two pipe" system and my many fuel-based woes are no more.

John Owen 11-07-2007 03:20 PM
The blockage may have caused cavitation, overheating, and destruction of the pump. They will die quickly if run dry. The above suggestion to check flow outside the car is good - changing to Aeromotive is better.


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