Fuel Pressure Problems

Okay, after 3 new pumps, fuel pressure in the car still drops to 0 immediately after turning off the ignition. It idles at 36psi, and 47 WOT. The FPR, and fuel filter are relatively new...maybe a year old.

Ruling the fuel pump, and check valve out, what else would cause my fuel pressure to drop to 0 as soon as the ignition is turned off?

btw, the new pump is a walbro 255 in the bucket.

Fuel pressure regulator damaged, leaking injectors, leaking lines.

Would leaky injectors cause the pressure to drop immediately to 0? None of the lines are leaking, so best bet is the regulator?

It doesn't take much loss of fuel to drop the pressure. You can check the injectors by pulling the rails up and priming the pump.

What type of pressure gauge are you getting your reading from?

Ken R.

Okay, we just ruled out the FPR by hooking it up to another TA. Checked out the injectors and they're not leaking. We also can't find any line leaks. I'm totally lost now.

What type of pressure gauge are you getting your reading from?

Ken R.

An analog fluid needle type, not sure on the brand, the car is at a friends house and he's relaying this information to me.

Keep in mind that a single drop of fuel lost in a hydraulic system could drop the pressure to 0 from 40.

Keep in mind that a single drop of fuel lost in a hydraulic system could drop the pressure to 0 from 40.

So, what should I check for on that?

Are you having hard starting problems?

Yes, about 6 second starts.

Still working on it, anyone have any other ideas?

I had same problem it was the regulator (Aeromotive was no good stock unit is fine up to 900hp).. Went back to the stock unit and had no problem. The cpu controls FP anyway... Good Luck....

I had same problem it was the regulator (Aeromotive was no good stock unit is fine up to 900hp).. Went back to the stock unit and had no problem. The cpu controls FP anyway... Good Luck....

How does the cpu control fuel pressure? It has no way of even knowing the fuel pressure. It will adjust the injector pulse width to compensate for a lean condition caused by low fuel pressure, within limits, but the PCM does not control the pressure.

Interesting that you mentioned problems with the Aeromotive AFPR. Seems to be a frequent problem.

Found the problem, and it ended up being something pretty stupid. The kink free plastic hose that came with the pump was to large to completely seal on the out take nipple of the fuel pump. We replaced it with a rubber hose and it now hold pressure great.