fuel pressure problems

[philip j]

So my EFI started running like crap about 3 weeks ago, out of no where! The rear pump was noisy, so I thought it was getting weak. Fast forward, new 044 rear pump, new fuel filter, still runs lean. When the car is cold, I can bump the fuel pressure up to 55lbs, by hitting the keys a few times, but the pressure drops to 25PSI within a few seconds. When the engine is warm, I can't build pressure by doing this. I can start the car by adding extra fuel via the EFI programmer, but as the car warms up the fuel pressure drops to about 5PSI at normal operating temp, still adding the extra fuel via EFI programmer. Can I assume the 964 FPR which was new last year has gone bad? Voltage at idle is about 13.8, and manifold pressure is -12.9 - 14.1 Could there be a vacuum problem to the FPR, and not seeing it at MAP? All the lines appear to be in good condition. Any suggestions appreciated. Philip

[xbmwguy]

Phillip I would bet its the FPR. Go with the aeromotive its kinda bulletproof and you have full adjustability

[smurfbus]

Also check voltage at the pumps and that all grounds are good.

[philip j]

Originally Posted by smurfbus

Also check voltage at the pumps and that all grounds are good.

checked voltage key on, but car not running: 12.05V at pump on positive post, .22V on ground post. 12.85 V at battery. I think that's enough voltage to spin the pump properly. Philip

[philip j]

Turns out to be a fuel pump relay, works sometimes/others not Philip