Question for those of you with Walbro fuel pumps...

[bobafett]

Hey I know some of you have Walbros in your car, and I want to see if the way my fuel system behaves is 'normal', although I suspect it is not.

I am using a AEBS B16 intake manifold, with an AEM fuel rail, and AEM adjustable fuel pressure regulator. I am using a 6-AN fuel line from the stock fuel filter to the inlet on the AEM rail.

I am using stock injectors, and a walbro 255lph hp (high pressure) fuel pump.

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Here is the issue, and I want to know if it is normal or not...

When the fuel pump is running, it has absolutely no problem maintain pressure, but the second I shut off the car, the pressure drops almost immediately, in a matter of 2 or 3 seconds there is hardly any fuel pressure.

I know with a stock setup the car maintained pressure for hour, but ever since I changed all this shit around and added the walbro, I can't maintain pressure when the pump is off.

I am not leaking any fuel, and I don't smell any leaks at the tank where the pump drops in. All injectors are dry and fuel filter is dry.

I have checked several times and have never been able to find a source of a 'leak' and as fast as pressure is dropping off, it would have to be a BIG leak.

Anyway if you guys with walbros have the same scenario I will not worry about it. I was hoping it was a function of the pump to not HOLD pressure when there is no power to it. That would explain my situation.

Thanks guys..
Chris

[AccordEpicenter]

im pretty sure there is a checkvalve in it to keep it primed, So if your still losing fuel pressure, i would check your fpr, i know at least one guy that had funny fuel pressure problems with an aem fpr, if the fpr is good, i would check for leaks between the pump itself and the like 4 inch long piece of hose on it to the metal hard line that goes thru the cap on the tank. If you are still having problems after that, id replace the pump, but i think its the aem fpr personally.

[EricW]

My pressure drops, but not that fast. Like AccordEpicenter said it could be the fpr, I've never checked to see if that was it. I have a cheaper adjustable Fpr, it works but i have been thinking about replacing it with a better one.

[bobafett]

yeah i actually called walbro today and they confirmed what you say jason, that the pump does have a check valve, and should not relieve any pressure.

I will see if I can dig up another regulator and test that shit. Would suck to have to buy another regulator lol. Oh well. :P

Thanks for your inputs guys!