redstang97

Ive heard different ways to adjust the FP regulator and I would like to know which one is correct? They say to take the vacume hose off, plug the hole, then make your adjustment. Is this correct, and if so why does the FP go up when I remove the vacume hose. What would be a good pressure to run once I figure this out? Thanx

Eagle2000GT

I have only a basic understanding of the system, but inorder to get the correct A/F mix the computer has to adjust fuel pressure according to vacuum (or pressure in supercharged applications). Too much fuel pressure and the injectors put in too much fuel. Too little fuel pressure and the car runs lean. But as vacuum decreases or boost increases, a higher fuel pressure is needed to put in the correct amount of fuel. The computer compensates for this.

A Ford mechanic told me that my fuel pressure was 43 psi (normal). But I believe thatthatwas thecomputeradjusted number. My Autometer fuel pressure gage reads approximately 30-32 psi.A tuner said to reconcile the differences between the two you subtract vacuum or add boost in psi to the computer corrected number (43 psi). Vacuum is approximately 25 inches (12 psi) at idle. If I subtract that from 43 I get 31 psi (unadjusted fuel pressure) . At WOT (little or no vacuum) my fuel pressure gage goes up to approximately 40-45 psi. With novacuum it should be 43. At 6000 rpm I'm running about 8 psi of boost. My fuel pressure gage should read around 51 psi. (I don't really know because at 6000 rpm I don't have time to look at anything but the tach.) Even though the computer adjusted fuel pressure (what the Ford mechanic sees) is a steady 43 psi, my fuel pressure gage is swinging all over the place depending upon whether I'm at WOT or not (depending on whether I have vacuum/boost or not).

I spent a couple of hundred dollars having my car checked out because lately my Autometer fuel pressure gage has been reading high in stop and go traffic. Wasted money. Nothing was wrong. The tuner also said that the computer adjusts fuel pressureaccording to tempature to keep the fuel from boiling in the fuel rails and spraying vapor into the cylinders. The Ford mechanic saw this when he data logged my car. With the engine hot in city traffic the computer took the adjusted fuel pressure to 53 psi.The result is that I see a higher fuel pressure onmy Autometergage at idle but less swing when I go WOT.