Unstable Fuel Pressure
 

I have recently added a 255LPH fuel pump on my 199 Mustang cobra 4.6 4V, as part of a supoercharger upgrade. None of the other modification have been installed except for the pump. When I driver the car, I get radical fuel pressure fluxuations from 35-60 lbs under load.

Is this normal??? Does a chip fix this???

Thanks!

does you car idle fine? when i was having problems with my speedpro. my fuel pressure was fluctuating. i got a NOS fuel pressure gauge and installed it right on the fuel pump. with 83# injectors and speedpro work. problem solved.

A chip may help. Or you can get an adjustable fuel pressure regulator which might remedy the problem. It could be a bunch of things though like logged fuel rail, dirty injectors, bad O2 sensors, or just bad gas. It proably is just one of those problems that is just annoying not very serious.