Ford F150 - not getting fuel

I have a 1991 Ford F150. It stalled while driving, like it ran out of gas. I’ve since replaced the fuel pump relay, fuel pump, and fuel filter and still can’t get it to start.

Any ideas? I’m at a loss.

First things first. Are you really sure that this is just a fuel delivery problem? A quick way to tell is to spray starting fluid into the throttle body or air intake while cranking the engine. If it fires up a little bit, then you can assume that fuel is the problem. If it doesn’t, then it will be ignition or ignition and fuel.

Is the PCM getting power?
Is the fuel pump getting power? Is it running? What is the fuel pressure at the rail?

Engines need fuel, air and spark. Sounds like you got the fuel covered so let’s move on to air and spark. Air is usually a given so have you checked the spark? Some of these engines use a ballast resistor which can be problematic. I bet you have little or no spark.

Actually, I think that 91 used the TFI module. I don’t think those used ballast resistors.

I was able to get the truck to turn over when I used starting fluid. I also disconnected the fuel filter to see if I could get fuel to pump out. No fuel came out of the line when I turned the key on.

I also need to mention that this is the front tank on a dual tank system. I also tried switching to my rear tank with no luck.

Okay, that’s good information. Do you hear either of the fuel pumps running? Can you measure 12V power at either of the fuel pumps?
Basically, if the fuel pumps aren’t getting power, then the next checks are:
Are all related fuses good?
Is the fuel pump relay or relays getting power?
Is the inertial fuel pump cut-off switch passing power like it should and not tripped?
How about the fuel tank selector switch?

It isn’t the fuel tank selector.
From what I can tell, the fuses are good.
I didn’t hear the fuel pumps running.
At the moment, I don’t have a way to check the voltage on the relays.

Is the inertial fuel pump cut-off switch passing power like it should and not tripped?

Not sure how to check this

I just located and checked the inertia cut-off switch. I disabled it and re-enabled it with no luck.

Look at the diagnostic connector under the hood where codes are pulled. There should be a tan wire with a green stripe. Run a jumper wire from that terminal to ground.
You should hear the pump run and the truck should start if this is a lack of fuel problem.

If the truck does run then disconnect the jumper wire. This means that for some reason the fuel pump relay is not getting a ground through the ECM.
This could be caused by a faulty TFI ignition module, faulty ECM, etc.
If it does not run then it’s very well could be a faulty pump relay.

Take a test light and connect it to that tan/green wire in the diag. connector. Turn the key to the RUN position. The light should be on. If not, likely a faulty ECM circuit.
If the light is on, crank the engine over a bit. After 3 or 4 seconds of cranking the light should still be on. If not, a likely TFI module problem.

(I should have added that pulling the codes might not be a bad idea just in case there is a loss of PIP code; this being the signal the TFI module sends to the ECM which then triggers the pump relay based on that signal.)

I think it would be well worth it for you do buy a DMM (a $25 one should be more than good enough) and to get some wiring diagrams for your truck. Also, be sure to try OK’s suggestion below.

All engines in the 1991 model year used a ballast resistor (ballast wire) (resistance wire) for the F-150 2 and 4 wheel drive models. If you are not getting spark then I would check out this wire. This is a pretty common problem when the engine shuts down without warning.

I was able to check the fuel pump relay with a light meter and determine that it is getting power. The fuel pump is also getting power. I can hear it running when I turn the key to the ON position. I even hooked the fuel pump directly to the battery and it ran fine. I also hooked my old fuel pump up to the battery, and of course it ran fine too.

So my problem is happening after the fuel pump.

I also remember that there was no fuse in place for the tank selector switch. After I put a fuse in, the tank selector switch started working. I switched to my rear tank and the truck started and ran for about 20 seconds before shutting off.

Any ideas?

The engine is getting fuel, but now I can’t get it to start even using starting fluid. The spark does look weak. I could not locate the ballast resistor wire.

Could it be something else like the coil, spark plugs, spark plus wires?
How would I check this?

The pump will run initially when the key is first turned on but only for a couple of seconds. After that it shuts off, unless the engine is being cranked over by the starter motor.

The tan/green wire I mentioned is a splice wire that is tied into the trigger wire from the fuel pump relay to the ECM. This wire provides a ground for the pump relay through the ECM when the key is first turned on but will lose this ground within about 2 seconds.
The ground should reappear if the engine is cranked due to the ECM receiving the PIP signal from the ignition module.

This could be verified with a test light by connecting it between battery power and the tan/green wire in the diagnostic connector. You should see it light up with the key on, go out after a few seconds, and then come back on when you crank the engine.

It’s possible to have an ignition module fault which can then lead to an inoperative fuel pump. This may show up as a code for loss of PIP or something like that.
It’s also possible to have an internal ECM fault which means no ground to trigger the relay.

Not really sure what happened but I installed the fuel pump and the engine was getting fuel, then we noticed it wasn’t getting fire. Eventually I figured out it was the coil. I replaced it and now the truck is running. After it was all said and done i wish I had just taken it to a pro who could have diagnosed the problem more efficiently. I wasted a lot of time and money buying and replacing parts that I didn’t need.

I have a 1987 F150 with the 302 in it that’s not getting fuel , what ended up being the problem for you ? We have changed the relay the fuel pump and the tank , with the starting fluid it cranks up but won’t start running.

read the reply just above yours…

I just signed up idk how to do that but I’ll check it out .