1994 Ford Ranger

JFLOYD1

MEMBER
1994 FORD RANGER
6 CYL
4WD
AUTOMATIC
350,000 MILES

Should I have a reading on fuel pressure after this truck sets all night? I checked it after I bought a pressure tester and went through the process as my book requested. I left it connected in just a few minutes I could see the needle going down to 0 with engine off. With the engine running the pressure was between 35 and 40 psi. Just for information the truck runs great and has lots of power. I just got through doing a valve job, it has new fuel injectors new o rings, all new gaskets and a new presure regulator, a new fuel filter. I have noticed that when I crank it some black smoke comes from the tail pipe but goes away after it cranks. I can hear the fuel pump running for about 1 to 2 seconds. After running the engine for a few miles and then cutting it off the truck will crank real good but if I leave it off for 15 to 30 minutes it cranks with the black smoke coming out the tail pipe. My compression is 178 to 180 on cylenders. Thanks for any help with fuel pressure problems.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,709 POSTS

It shouldn't drop that fast. It could be a bad check valve in the pump itself. You would have to check that. However, the black smoke tells me it is running rich at first. That leads me to believe you may have a leaky injector. What you need to do is turn the key to the run position to build pressure. Then, pinch the rubber fuel line from the fuel tank. If the pressure still drops, you have an injector or pressure regulator leaking down. If it doesn't drop, chances are it is the check valve in the fuel pump or a leak somewhere in the line.

Let me know what you find.
Joe