Hey people Im still trying to figure out a intermitent idle / power issue. I have a fuel pressure guage hooked up to my car when i turn on the key the pump primes to 43 psi and then drops to 0 like really fast as soon as the pump shuts off.as long as the pump is running the presure is at like 38-43 psi but when the pump is off it just drops instantly to 0 psi.Shouldnt it hold pressure for awhile?

Yes it should hold pressure even after you take the key out.

If you're loosing pressure right away you have a leak in your fuel system.

or, its an electrical guage, plugged into your acc switch. when the key turns off, the guage does too, just like your stereo

it's a mechanical guage in line between the fuel filter and fuel rail.

When you repleced the fuel pump didi you reuse the stock fuel line clamps. If so you want to replace them, they arent designed to hold the pressue of a larger pump.

I never replaced the fuel pump it is the stk pump.when the car runs i have 37 psi at idle.When i shut the car off i loose presure instantly.It looses so fast i cant even see a gradual neadle drop on the mechanical gauge i have in line it just goes to zero.

I have the exact same problem. I installed an aeromotive FPR and it was working like it was suppose to, when the fuel pump primed the system with the ignition open the pressure would stay up between 30 and 40 psi for while; but now when the pump primes the system and turns off I can see the fuel pressure gauge drop to 0 in like ten seconds. I don't smell or see any fuel leaks in the engine bay. I checked the hoses on the fuel pump and they were ok. Anybody has any idea of what could be the cause?

PS I got a TT pump

I was checking around and found some answers for us.First we should have 43 psi of fuel pressure "according to a manual i seen" second if we are loosing presure that fast after the pump stops then we have a bad regulator or a bad fuel pump.It may be bleeding back from the presure side of the line through the pump or it is bleeding past the regulator back the tank.To check and see which one it is just clamp off the fuel line on the presure side of the system befor the fuel rail and place a guage in the line between the pump and the piont you just clamped off. if you still loose presure it is the pump, it must be leaking out or it is bleeding back through the lines and past the pump.If not then it may be the regulator.To check this you clamp the line after the regulator and do the same thing.This is what I am going to do.If anyone has any comments on why or why not this would work go ahead and through your change in.You will lose some presure after the car sits for a few min. but not like we are discribing.The real scary part is are we going lean under boost because of poor fuel presure?? Only the big guy knows!!!!!!!Not something im going to chance.

Well I checked the line that is before the fuel rail and it did the same thing, the pressure went all the way up to 100 psi and gradually went back down to 10 psi in like 15 sec. and then to 0 psi in 2 minutes. The thing is that when the car is @ idle the pressure is where is supposed to be for the 4bar program(49psi w vaccum line and 59psi w/o it). So it looks like the pump is not holding the pressure. How do I go about fixing this besides getting another pump. This pump only has about 2 years , it is an original nissan 300tt pump. :confused:

I donk know if i would go changing the pump out if it only has 2 years on it.That is very strange to a pump fail in that time frame.It does sound like that is your problem though.So you clamped the line off befor the fuel rail?If so and it still bled then yes it sounds like it is pump.

I clamped the hose coming out of the fuel filter. Did you test the fuel lines on your car?