how do u tell if an fmu is not working properly (besides ur fuel pressure not rising)? I took mine apart while attached to my car and the diaphram is in tact but when I looked at the metal piston in the middle, it wouldn't move. Is this thing supposed to move up and down easily, cuz I tried to push it down since that is the way the boost would bush it and it doesn't move.

 

Take it out of the car and turn the FMU upside down and see if it slides out. it can only go down so far......

 

has anyone taken apart their fmu and tried to push down on that center piston? Is it supposed to be easy to push down and is it pretty much supposed to be free flowing? Cuz mine is like seized and impossible to push down. My buddy is letting me try his out but not until tomorrow. In the mean time, I want to see if this is the problem.

 

hey by the way if if happens to be defective. I have one for sale. I hope you get your problem fixed.

 

just out of curiosity have you used it as is on your car, and if so what did it cause the car to run like.(rich , lean, etc.?)

 

I don't think I need to get a new one as the guy I bought it from said that he will either give me a new one or my money back. As for the unit, it works up until I hit boost. Because my engine runs rich as it is, I can handle about 1 psi or so and from there it starts to go lean. So in vaccum I'm fine but once I try and hit wot, it goes right into the red zone! So I'm taking it really easy, but suprisingly I can still hit boost at part throttle and I'm still on the rich side of my a/f gauge.