Fuel pressure problems

[Lonnie Greene]

I have a 1996 Explorer Sport 2 door 4.0. The fuel pump stopped working. I replaced it and installed a new filter. Fuel pressure was 37 psi. Every thing looked OK.I started the motor, went on a test ride. I got pulled home. I checked fuel pressure again. After it ran for a short time pressur started dropping. The motor stopped. This Explorer has over 145000 miles on it. I checked the fuel pressure regulator. Vacuum lines OK. I changed the regulator. Same problem. I "jumped" the relay and the pump ran. Started the trying again. With relay jumped I still had the same problem. It runs great until the pressure drops. I have checked he MAS,EGR, all vacuum lines. Now it is time for a little wild turkey. Any help would be great. (Whit the pressure problem not the turkey,unless you are nearby.

 

[Rick]

I hate intermittent problems like that. Possibly a bad replacement pump?

 

[Lonnie Greene]

Could be. But the old pump started the same thing before it died. I think I will try to jump the fuel pump safety switch tomorrow.

 

[Lonnie Greene]

Could be. But the old pump started the same thing before it died. I think I will try to jump the fuel pump safety switch tomorrow.

 

[CDW6212R]

Was the old gas at all dirty, either in the filter or the tank? If either were fouled a lot, that would be the issue, more debris in the tank. If not, was the rubber hose replaced in the tank, clamps decently tight?

When the pressure "drops" is it all or nothing, or a slight drop in pressure? If it goes down to very little or nothing, I'd check the wiring connectors on the bottom side of the pump relay etc. The individual wire terminals can let go from inside of the connectors they lead to. Those are the first things that come to mind from what you described.

 

[Lonnie Greene]

The fuel was extremely clean. The filter was really bad. The pressure drops nearly all at once. I don't have any rubber hose in the tank. The lines in the tank are metal. They have the nearly impossible to remove "quick disconnects. I plan to check the wiring today. ( I have over 30 years experience in industrial control) I believe you are correct about a loose connection. I just need to find a diagram. Thanks four your help I should have thought of this after stalling the new pump.

 

[2000StreetRod]

Power for the fuel pump goes from the fuel pump relay to the inertia switch located above the front passenger foot area. Try resetting the inertia switch. Then check the electrical connectors from there to the fuel pump. On my Sport there's an electrical connector mounted on the inside of the frame rail below the driver position.

There's another one above the leaf spring near the fuel pump.

 

[J$hort]

Check all wiring. Hopefully it is not a bad connection at pump. Do you get the fuel pump initially running when turning the ignition on after pressure loss?