Intermittent fuel pump issues with a 1987 ford ranger

[RustyDusty]

Hey, my girlfriend has a 1987 ford ranger with the 2.9 that’s been having intermittent no-starts. She described to me that the truck would start just fine when it was cold but she’d park somewhere and when she’d come back 10 - 30 minutes later it wouldn’t start. She’d wait and eventually it would start up. Sounded like she was describing the same issues people have with the TFI module overheating so first thing I did was remove it from the distributor and put it in a heat sink from an Aerostar and installed it somewhere away from the engine heat. We’ve been driving it around for a few days and she was amazed it hadn’t skipped a beat when starting up while the engines hot. Everything seemed to be fixed until today we were a ways from home and went on a hike. When we got back to the truck it wouldn’t start. This was the first time I had experienced the issue and I noticed the fuel pump wasn’t priming. I turned the key several times to keep trying to listen for the fuel pump but it wasn’t making a peep, just the relays clicking away. I kicked the bottom of the fuel tank and still nothing. I decided to ground the #6 port on the DLC to manually send power to the fuel pump and I just heard the relays click and no fuel pump. Did this several times and eventually heard the fuel pump kick in. I removed the wire from the #6 port and had my girlfriend start the truck. It started and ran for a few minutes then died. I grounded the #6 port on the dlc again and wasn’t hearing the fuel pump, just the relays clicking again. Tried several more times and eventually heard the pump kick in, had her start the engine and I left the wire grounding the DLC for the drive home. The truck seemed to drive fine for the 30 or so miles home on back roads until we had to get on the freeway. The truck showed some sputtery hesitation going 60 uphill but it pulled through and we made it home. I’m wondering if this whole story makes a clear case for a failing fuel pump or if I should try diagnosing other parts before leaping to that conclusion. Thanks so much if you made it this far!

 

[Shran]

I would check the two wires right at the high pressure pump... I have had them simply fall off the pump before. Would also recommend checking the plug at the sending unit...the plastic gets brittle and they fall apart fairly often. One more place to check is the ECM/fuel pump ground wire that is part of the negative battery cable. I have seen that connection go bad as well as the connector about 6" down the wire from there.

Could just be a bad pump, but rule out wiring first. I would recommend focusing on the high pressure pump first, in my experience they rarely go bad, but that's the one you will hear running... the in tank one is very quiet.

 

[RustyDusty]

Perfect, thank you! I had to replace the high pressure fuel pump on my 1989 e-150 already and it cleared up some issues it was having (intermittent, sputtering loss of power on the freeway, wandering idle while warming the engine almost to the point of stalling. The ranger was experiencing these same issues yesterday). I’ll check the wiring first to make sure it’s not electrical before replacing the pump.

 

[bobbywalter]

Pull the plug off and look at the sending unit....they corrode to death sometimes.

 

[alwaysFlOoReD]

The majority of fuel pump problems ive had are at the connection at the high pressure pump on the frame rail. Pull the rubber boots back and replace the female spade connectors.

 

[RustyDusty]

So I checked out the points of interest suggested by everyone here and nothing seemed suspect. Surprisingly the high pressure fuel pump looked fairly new. Looks identical to the Bosch one I installed on my e-150 a few months ago. The connectors look bright and shiny, the wiring harness coming from the engine bay to the fuel pump looks to be in good health. I tested the voltage and its getting 12v. I'm doubting it's an electrical issue but I'm also surprised the pump would be going bad since it appears to be new. My girlfriend bought this truck from a father and son who had been restoring it together and they'd already done a lot to the truck to get it running well (new plugs, wires, cap, rotor, IAC, temp sensors, and apparently the high pressure fuel pump. Couldn't get a great look at the fuel filter down stream from the high pressure pump, its annoyingly tucked away! Anyways I think we'll just keep driving it as is and keep a multimeter in the glove box for when the pump stops working again, I'll check the voltage at the high pressure pump contacts and if its getting the proper voltage I'll be almost certain the pump's just toast.

 

[RustyDusty]

So today we were on our way home in the truck and while turning a corner the truck died and I rolled into a parking spot, put it in park and took out the multimeter. I didn't have a way of connecting the multimeter directly to the high pressure fuel pump while the pump was plugged in so I just tapped into the inertia switch and had my girlfriend turn the key to prime the pump. I heard the pump prime so I had her try a few times, it primed each time and I was getting 12v so instead of waiting around for it to not work we just started the engine. I kept watching the multimeter hooked up to the inertia switch with the engine running waiting to see if the engine would die again. It was pretty steady at around 13.7v until it jumped to over 14v at the exact moment the idle dropped so low it alllllmost died but it caught its breath and went back to idling normally, the voltage was back to 13.7v. My best guess of what happened there is the high pressure fuel pump crapping out for a sec and relieving the electrical system of its energy draw spiking the voltage to over 14v until the pump kicked back in and brought the voltage back down to 13.7v and saved the engine from stalling. Curious to hear anyone else's thoughts on this. I'm fairly convinced that despite the pump appearing to be pretty new that it's failing and needs to be replaced. I'll replace the fuel filter as well. I don't know the state of the gas tank interior unfortunately. Is it possible for crud in an old gas tank to choke the high pressure fuel pump enough for it to not even turn on sometimes but work fine at other times? I feel like at this point the pump is the obvious answer here, I just don't like to throw parts at a truck before actually understanding what's wrong with it. Thanks!

 

[gaz]

Rustydusty,

Have you checked for trouble codes.

One thing I would try when it isn't starting is a 50/50 with starter fluid, just to conclude wether you have a fuel or ignition problem.

There are 3 fuel filters in this:

1) a filter sock before the low pressure pump in the tank
2) a low pressure filter before the high pressure pump
3) the high pressure pump output filter

Any one of them could cause fuel flow issues. I am curios what your fuel pressure is when primed before starting, while running and immediately after shutdown. If you are confident that the fuel filters are all good and working properly, the electrical side of the fuel system is pretty simple.

Any puddling up by the intakes?

If this rig is a manual transmission, take a look at the nuetral sensing switch on the clutch pedal arm. If it is acting up it can keep the engine from starting. It can be bypassed but then the computer will aways let you crank the starter, even when it's running.

A new gas cap is a small investment but can also cause fuel pressure issues.

 

[bobbywalter]

The low psi in tank pump may be dead.


The fuel pump is not necessarily the volt spike on the alt.

 

[89Twincharge]

Well I think your off track looking at pump... ford used metal shielding cable for the tfi ignition that over time rubs through wires and can cause all kinds of problems and the ECU uses distributor to trigger fuel pump. With key forward follow tfi harness and jiggle wires. If you hear the pump randomly coming on and off then
that may be your culprit....

 

[RustyDusty]

Well I think your off track looking at pump... ford used metal shielding cable for the tfi ignition that over time rubs through wires and can cause all kinds of problems and the ECU uses distributor to trigger fuel pump. With key forward follow tfi harness and jiggle wires. If you hear the pump randomly coming on and off then
that may be your culprit....

Thanks, I think this could be it. The fact that the high pressure fuel pump appears to be new makes me think the previous owner was working on tackling this issue and might have had the same thoughts as me that the high pressure fuel pump was to blame and replaced it but obviously the issue persists. The previous owner also replaced the TFI module so they were definitely trying to figure something out and were probably looking around on this forum. I'll follow the TFI harness and look for anything irregular and also try jostling the wire's a bit to see if it affects whether the pump comes on or not. When I turn the key forward the pump is supposed to prime for 2 seconds, are you saying if I leave it in that position and jiggle the wires the pump might come on randomly if there's some wire damage? I would have assumed the pump would only be getting power in those initial 2 seconds when the key is turned forward.

 

[RustyDusty]

Rustydusty,

Have you checked for trouble codes.

One thing I would try when it isn't starting is a 50/50 with starter fluid, just to conclude wether you have a fuel or ignition problem.

There are 3 fuel filters in this:

1) a filter sock before the low pressure pump in the tank
2) a low pressure filter before the high pressure pump
3) the high pressure pump output filter

Any one of them could cause fuel flow issues. I am curios what your fuel pressure is when primed before starting, while running and immediately after shutdown. If you are confident that the fuel filters are all good and working properly, the electrical side of the fuel system is pretty simple.

Any puddling up by the intakes?

If this rig is a manual transmission, take a look at the nuetral sensing switch on the clutch pedal arm. If it is acting up it can keep the engine from starting. It can be bypassed but then the computer will aways let you crank the starter, even when it's running.

A new gas cap is a small investment but can also cause fuel pressure issues.

I did check trouble codes, all I got was a 33 so I took a peek at the EGR and there was a rubber hose coming from it not connected to anything. Discovered the and had just shook loose from a black plastic sensor attached to the intake manifold. I hooked it back up and havent warmed it up and checked for codes again yet. Checking fuel pressure is a really great next step here. I'll do that soon.

Puddling by the intakes? of gas from the injectors/fuel rail or something else? I didnt see anything like that.

Its an automatic transmission

 

[89Twincharge]

Thanks, I think this could be it. The fact that the high pressure fuel pump appears to be new makes me think the previous owner was working on tackling this issue and might have had the same thoughts as me that the high pressure fuel pump was to blame and replaced it but obviously the issue persists. The previous owner also replaced the TFI module so they were definitely trying to figure something out and were probably looking around on this forum. I'll follow the TFI harness and look for anything irregular and also try jostling the wire's a bit to see if it affects whether the pump comes on or not. When I turn the key forward the pump is supposed to prime for 2 seconds, are you saying if I leave it in that position and jiggle the wires the pump might come on randomly if there's some wire damage? I would have assumed the pump would only be getting power in those initial 2 seconds when the key is turned forward.

Yes after the prime leave key in on position... the tfi harness meets up to another and then through the fire wall to passenger side ecu. Might as well remove the loom since its gonna be brittle anyway. You'll see the braided shielding around the tfi wires.... if there is a break or rub in wire insulation I'd recommend removing the braided shielding cable and either re wrap with shielding tape or junkyard a dual newer(89-up) wire harness and using the updated "taped" tfi wires...

 

[bobbywalter]

Ground pin 22 for the wiggle test....it's on the house looking connector for the obd1 tester.

This will run the pump untill you in ground it.

Then wiggle/yank test the eec harness. You can volume test as well...

I run with a psi gauge for trial as well


If this works out ...sweet..

Otherwise..
The low psi pump is often overlooked and has intermittent issues as well. If the sender is new then it's probably all new

 

[gaz]

Rusty,

Does it start with starter fluid shot into the trottle body? That is the 50/50 test; it tells if you have a fuel.or a spark issue.