I have a 92 F150 with the 351W engine and have been having some performance problems. Yesterday I noted fuel pressure of 25 psi and a wildly fluctuating pressure on acceleration so I changed the fuel pressure regulator and got an increase in pressure to 32.5 and steady pressure. The book says it should be 39.5 psi. There was a considerable performance increase after I changed the regulator but it is still sluggish on acceleration.

1. Is my next option to replace the fuel pump in the tank? (was dual tanks but the rear has been removed)

2. Should the pressure increase when I remove the vacuum line from the regulator? There is no change in the pressure when I do so now. Perhaps my fuel pump is limiting me to 32.5 psi?

Thanks

 

your fuel pressure should be around 32 PSI with the vacuum line connected and 39-40 with it disconnected. If you apply pressure to the regulator fuel pressure should increase by 1 PSI for every PSI of air pressure you apply.

 

I pressurized the fuel pressure regulator and could not get more than 34 psi fuel pressure. I then replaced the in tank fuel pump (regulator was new) and got 40 psi with the vacuum disconnected and 35 psi with it connected. Truck runs great now with lots of power all around.