Need help with 94 ranger wont stay running.

[CelebrityBob]

So I have poured over forums trying to resolve this issue. I have spent so many hours on threads and troubleshooting. I have a 1994 ford ranger 4.0 auto with 4wd and only 68k on it. This began as an intermittent problem and that made it more difficult to diagnose. I have narrowed it down to a fuel delivery issue. It used to stall out when it got hot and I spent many times pushing it off the road in FL traffic. After it stalled I could wait 30 to 45 minutes and it would start again. So now it won't start when it's cold. The fuel pump is working. I have changed the fuel pump relay and the fuel filter. If I try to start it once it'll chug for a second and then die. If I turn the key off, wait for the pump to finish priming, turn key off, back on and prime again, I do this 3 or 4 times total to build up pressure in the line and when I start it, it starts up with a good little roar due to the fuel built up in the line and once its spent, it dies again. At fist I though this might be spark so I replaced everything in the line as far as coil pack, wires, plugs etc... I am wondering if this could be the fuel pressure regulator. I have no changed that yet. My truck is now at work, stuck there and I cannot get to the parts store easily. This is my situation. I humbly and desperately ask for help at this point. I forgot to mention, the inertia switch is fine too.

 

[scotts90ranger]

Back when I had a '91 Explorer I had a fuel pressure regulator fail, if you pull the vacuum line off the regulator and prime the system there should NOT be fuel there.

repeatedly priming the fuel pump should change nothing assuming all the injectors, regulator and pump are all working correctly.

Your pressure regulator could have been slightly leaking then just blew out completely. If I remember right it was a very simple replacement.

I don't remember, do the 4L's have a ignition control module like the 2.3L's did at the time?

 

[CelebrityBob]

Back when I had a '91 Explorer I had a fuel pressure regulator fail, if you pull the vacuum line off the regulator and prime the system there should NOT be fuel there.

repeatedly priming the fuel pump should change nothing assuming all the injectors, regulator and pump are all working correctly.

Your pressure regulator could have been slightly leaking then just blew out completely. If I remember right it was a very simple replacement.

I don't remember, do the 4L's have a ignition control module like the 2.3L's did at the time?

I will check the FPR vacuum line. And yes they have an ICM but I don't have a spark issue that I know of. This seems to be a fuel delivery issue. I am also going to try to jump from the battery to the FP power wire so it's always on and see if that works. If it does then I can assume once the vehicle "starts" the FP is not maintaining signal to stay on. I know the key on allows it to prime but I can't hear it on after starting. Also since I am one person right now idk if the relay is clicking back on after the "start" phase. If that's the issue it leads me to believe the possibility of the eec relay? Or something in that area.

 

[alwaysFlOoReD]

Iirc there is a way to jumper the test port to keep the fuel pump running. Tho I'm not sure if 94 has that.

 

[CelebrityBob]

Iirc there is a way to jumper the test port to keep the fuel pump running. Tho I'm not sure if 94 has that.

I bypassed the relay with the eec test port (obd test section) and it kept the pump running. So I was able to keep the pump on the whole time and the truck doesn't stay on. I pulled the vacuum line on the fpr and there is no difference in anything.

 

[CelebrityBob]

Back when I had a '91 Explorer I had a fuel pressure regulator fail, if you pull the vacuum line off the regulator and prime the system there should NOT be fuel there.

repeatedly priming the fuel pump should change nothing assuming all the injectors, regulator and pump are all working correctly.

Your pressure regulator could have been slightly leaking then just blew out completely. If I remember right it was a very simple replacement.

I don't remember, do the 4L's have a ignition control module like the 2.3L's did at the time?

I pulled the fpr vac hose and tried to start and had no result. I didn't see any fuel in the line but the vehicle would not start. I don't have the equipment to test fuel pressure at the rail on the Schrader valve. Right now my truck is stuck at work. I found a fpr for $30 and should be here this weekend. I'm going to replace it. Hopefully that fixes the issue. If not, idk what to do next.

 

[alwaysFlOoReD]

I bypassed the relay with the eec test port (obd test section) and it kept the pump running. So I was able to keep the pump on the whole time and the truck doesn't stay on. I pulled the vacuum line on the fpr and there is no difference in anything.

I would tend to think its electrical then. Something that is getting hot and stopping working. TFI was a problem back when there was distributors. Not sure about this...

 

[pentode]

I'll just throw this in there... I've heard fuel pumps make noise but no pressure. I feel like testing pressure at the rail is the first move to make.

 

[CelebrityBob]

I would tend to think its electrical then. Something that is getting hot and stopping working. TFI was a problem back when there was distributors. Not sure about this...

But the engine is cold. At first it was intermittent. Now it's not.

 

[CelebrityBob]

I'll just throw this in there... I've heard fuel pumps make noise but no pressure. I feel like testing pressure at the rail is the first move to make.

Well the pump is building pressure. It starts then sputters out immediately burning what's in the primed fuel line.

 

[alwaysFlOoReD]

But the engine is cold. At first it was intermittent. Now it's not.

Oops

Maybe a wiring issue; bad grounds or loose wire.

 

[pentode]

Well the pump is building pressure. It starts then sputters out immediately burning what's in the primed fuel line.

Well... I don't know what the spec is for fuel rail pressure off the top of my head but if it needs 50psi and it's making 5, it's going to do exactly what you're describing, no?

It's going to spin and make noise but not push enough fuel up there to keep it running.

Edit: re-reading your initial post, you describe a slowly deteriorating condition... that seems to line up with failing fuel pump too.

 

[CelebrityBob]

Well... I don't know what the spec is for fuel rail pressure off the top of my head but if it needs 50psi and it's making 5, it's going to do exactly what you're describing, no?

It's going to spin and make noise but not push enough fuel up there to keep it running.

Edit: re-reading your initial post, you describe a slowly deteriorating condition... that seems to line up with failing fuel pump too.

Generally fuel pumps (being electric motors) are either on or off. At least that's my experience. Also once they start running they tend to stay running. And when they fail they are just off and won't turn back on. With my issue, previously it would run and then sometimes die. I guess I will find out though. After the FPR that will be the next step. Changing out the fuel pump is not a fun ordeal on this vehicle.

 

[pentode]

Generally fuel pumps (being electric motors) are either on or off. At least that's my experience. Also once they start running they tend to stay running. And when they fail they are just off and won't turn back on. With my issue, previously it would run and then sometimes die. I guess I will find out though. After the FPR that will be the next step. Changing out the fuel pump is not a fun ordeal on this vehicle.

Yes, the motor is generally either on or off. I'm not questioning whether it's running. There are also mechanical components to a pump that can also fail - impellers etc. You can definitely have an electric pump spin but not produce any pressure. A motor is not a pump. A pump is a motor or engine with a mechanical device attached to move a gas or liquid.

It's up to you whether you want to spend money on parts before you do all the diagnostics.

"It would run and sometimes die" and then not run at all sounds very much to me like a pump that was slowly on its way out.

 

[CelebrityBob]

Yes, the motor is generally either on or off. I'm not questioning whether it's running. There are also mechanical components to a pump that can also fail - impellers etc. You can definitely have an electric pump spin but not produce any pressure. A motor is not a pump. A pump is a motor or engine with a mechanical device attached to move a gas or liquid.

It's up to you whether you want to spend money on parts before you do all the diagnostics.

"It would run and sometimes die" and then not run at all sounds very much to me like a pump that was slowly on its way out.

Ok sounds good. I'll definitely try to get the pressure checked on the rail when I can. Hopefully tomorrow. That way I'll know. Even if I check the pressure on the rail and it's at 30psi, I believe what it's supposed to be when the vehicle is primed, will that tell me anything if the fpr is bad? The fpr is getting changed regardless. It's 30 years old so...