95' 4.0 explorer sport fuel pump keeps running no start..~FIX!

[95exploresport]

Searched and tried everything I could on here which leads me to ask:
I have a 95' Explorer with a 98' engine. Ran perfectly fine until the fuel pump started to go out (I guess) I would have to turn the key on (No start) until the pump shut off to start the engine. This went on for about two months until I said heck with this and changed the filter and Pump.

After changing all that It started right up....ran it down to the gas station, filled it up, drove it home and parked it. Went out the next day to start it and when I turn the key on the pump runs but keeps on running and truck will not start.

I'm baffled, please help

 

[95exploresport]

Nothing Huh?...Time to start over I guess

 

[poker4me007]

I would start by checking the fuel pressure at the rail..

 

[Turdle]

^^ definitely do this.
If you replaced the pump motor only, the little hose connection may have slipped off. Could be the new pump is a bad one, they are hit and miss unless you get a ford replacement basket.

 

[95exploresport]

Fuel pressure is 38 (not running just crank) Bought the Pump @ Rock auto

 

[koda2000]

Just for goofs, try swapping the fuel pump relay with another similar relay in the power distribution box. The pump should only run for about 2 seconds when the key is turned to ON. Maybe the F/P relay is sticking?

 

[95exploresport]

I did that, seen on here that was one of the things to try, On your second question the pump just keeps running while key is turned on. The old pump used to run for about a minute then stop before it would start. Thats why I thought the pump and filter needed changed. Now it just keeps running

 

[koda2000]

I think it's the PCM that decides when and for how long the fuel pump should run. Have you tried disconnecting the PCM harness and checking the pins? Sometimes just re-seating the PCM harness can help. Also re-seat the trans harness. Do you have a CEL on? Does the CEL bulb light during the bulb check?

 

[95exploresport]

No CEL but i'll try the reboot on the PCM...THXS!

 

[95exploresport]

no dice on the PCM, still no start......weird thing is like I said above It started beautifully right after I changed everything then sat over night and No start...very weird

 

[ExploderGuy66]

May want to pull the PCM, open it up, and check for damage (specifically bloated/leaking capacitors).

 

[95exploresport]

The pump continuing to run has to be a big give away on what the problem is I just don't know what that is. does the tank itself have to be sealed/pressurized to allow the pressure to build and pump through the line? and there are two lines right? if one goes to the Rail where does the other go? I'm thinking the other line may be the issue.
Thanks folks for helping me figure this out

 

[koda2000]

The pump continuing to run has to be a big give away on what the problem is I just don't know what that is. does the tank itself have to be sealed/pressurized to allow the pressure to build and pump through the line? and there are two lines right? if one goes to the Rail where does the other go? I'm thinking the other line may be the issue.
Thanks folks for helping me figure this out

I agree that the pump continuing to run is a big clue, but if the tank isn't "sealed" you'd have a gross vacuum leak, which would set the CEL with an appropriate code, but it would have no effect on whether the pump runs or not. Depending on model year, some Ex's had 2 fuel lines (feed and return) or only one feed line. A '95 would have had the metal feed and return lines from/to the fuel pump assembly. There is also a plastic hose attached to the tank that goes to the evaporation canister.

@95exploresport - The '95 would have hand a fuel pressure regulator on the fuel rail. IIRC the regulator is vacuum controlled and has no electrical connection. I really doubt it, but I wonder of the regulator could somehow cause the fuel pump to run continuously? I'm leaning more heavily toward a PCM problem.

Pressure regulator:

 

[poker4me007]

I agree with Koda2000 and Exploderguy66... Its probably the pcm... found this old post on another forum...
https://www.ford-trucks.com/forums/1121669-fuel-pump-keeps-running-and-truck-wont-start.html

 

[95exploresport]

Interesting, i'll try the Pressure regulator then if all fails replace the PCM

 

[koda2000]

Interesting, i'll try the Pressure regulator then if all fails replace the PCM

I really doubt it's the regulator. It would need to have an electrical connection to the PCM, which it does not. Try not to get in the habit of just throwing parts at a problem. I read the link that @poker4me007 posted and your problem sure sounds like it's the PCM.

RockAuto lists reman PCM's for between about $90-$175 (depending on part number) plus core. Unlike most sellers I've found I could return electrical parts to RA.

 

[95exploresport]

Ok.....Have the new PCM and that didn't work, going after fuel regulator tomorrow. hope it works

On another note: when I turn the ignition to "ON" the fuel pump runs (As stated above) then when I go under the hood I hear a hissing sound like the fuel is being pushed through VIA pump but it doesn't shut off. Vacuum only is in use while running right?

I took the intake manifold off to try and hear where the hissing is coming from and it sounds like the rail, sprayed soap to find it but no go.Looked at all the vacuum lines but no sign of cracked or leakage.
Crossing fingers that the problem is the fuel regulator.
Thxs again folks for your idea's, not gonna let my Explorer go, love this truck.

 

[Turdle]

At this point I think there may be a fuel injector stuck open.

Try starting the truck while holding the gas pedal floored.

 

[95exploresport]

Damn...Hope not, just replaced them two years ago, I have the fuel reg off at the moment. I'll try that when and if the new one doesn't work.

 

[koda2000]

At this point I think there may be a fuel injector stuck open.

Try starting the truck while holding the gas pedal floored.

Maybe. Would perhaps explain the hissing noise. Though by now you'd think it would be running out the exhaust pipe. Does the exhaust smell like gas? Does your oil smell like gas? Since a '95 uses a return-type fuel system the hissing might just be the fuel running back to the tank. I would think that if one injector was stuck open it would at least try to start. You could also pull your spark plugs after leaving the key on for a while and look for a wet plug.