91 KA24DE No Fuel Return.. ??

[DrSumtingWong]

Ive been having an issue gettin my car to idle and accelerate properly without breaking up real bad and back firing.. I recently discovered im not gettin any fuel out of the return side of my fuel rail. Rail is not clogged and Ive tried a new pressure regulator. Using a Snap-on Vaccuum pump the regulator requires a significant amount of pressure for the regulator to open and return fuel. Obviously i cant drive around with a manual pump hangin off my regulator so I also tried connecting vaccuum directly off the intake to my regulator and it still doesnt have enough pressure to open the regulator?? I dont know if this regulator works off of vaccuum and fuel pressure combined which could possibly lead to weak fuel pump and dont feel like wasting $$ on a new pump if not necessary. Any ideas or suggestions would be greatly appreciated.....

[navysnail]

IIRC it uses fuel pressure on one side of a diaphram combined with vaccum on the other side to open it, but i am not 100% sure. I will check the FSM tonight and get back to you on the answer

[teddy]

you are correct navysnail.

[jserrano]

Connect a vacuum gauge with a T-connector on the FPR vacuum hose. The reading should be about 19 in. Hg. or so. Slowly raise the throttle and see what happens to the vacuum. Post back your findings.