Ranger Starting issue - Not the fuel pump

[RangerBill]

Don't bother commenting anymore Bill if you are just going to insult the shop and not be helpful or constructive.

Ok, just trying to help, as you asked for advice.

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[TJC]

When my pump failed in my 2005 it was not catastrophic. The pump still ran, but the check valve failed. As soon as the engine was turned off the pressure would immediately fall to 0. I also believe that the pump was getting tired and couldn't hold high pressure... but maybe not.

The point here is ... if the pump is running the fuel is either pressuring the system or the gas is going on the ground. My fuel pressure regulator / check valve failed completely, and after I cycled the key 3 times the truck would start and run, not great but it ran.

Pull the line from the filter input and put a gauge on it, then cycle the key. You'll know in 5 minutes if the pump is running and pressure is building, and if the check valve is holding.

And one last thing. Don't trust a mechanic, you do it.

 

[RangerBill]

Two mechanics have gotten it to start by applying ground directly to the pump jumping/bypassing whatever electronics.

If this is true, then the problem is with the ground connection to the fuel pump motor. It would be easy to check with a volt/ohm meter.

 

[airline tech]

I will say I am somewhat confused on this issue, but if they can get the pump to run by applying a ground (which ground) the Relay Ground? or Pump Ground?

Relay Ground - affects the Power Feed and is controlled by the PCM, so a power check at the Pump is it a constant (12 Volt) power, as a voltage drop, or fluctuating voltage will cause a low-pressure issue. (Pump not spinning fast enough)
The PCM also has to see (ignition - injectors) for that ground to get it to run.

Pump Ground - This will affect the pump motor as well and also cause a low-pressure if the pump is not spinning fast enough.

Fuel Pressure Regulator - I would have to dig in the manual to confirm, but this should be a mechanical (vacuum controlled) regulator. It controls the fuel pressure going to the Fuel Rail (Injectors)
A bad regulator would cause start / running issues, but it would not dump power at the pump.
A quick check (if vacuum) controlled is to pull the vacuum line and check it for fuel if fuel is in the line the diaphragm is blown in the regulator.

So, at this point just to see what the pressure is doing, is to check the fuel pressure at the rail and then compare that to the fuel pressure at the fuel filter connection

Basically this - The FPR lets the fuel pump build pressure from the volume output of the spinning pump, and it controls that pressure but does not affect the power / ground control for the pump.
This is one of the reasons I suggested, disconnecting the fuel line and have a bucket ready to catch the fuel. I wanted to see if the pump was actually not running.

Hopefully, they can pinpoint it down, but yes - I would shift focus to what is the pressure, possibly shot gun a regulator at it and then if still an issue, backtrack to (where are they applying the ground to get it to run) what circuit and then dig into a possible issue on either ground circuit.
From what I gather so far, and your latest post- I would say it's the Pump Ground not letting the pump to spin fast enough.
Which brings us back to the G103 - right next to the Starter Relay you replaced, which is where I strongly believe the ISSUE is as you were at this area and then the ISSUE started.

So, to eliminate factors here, I would shot gun a FPR and also cut the ground wire a few feet from the fuel pump connector and run a new ground to a good clean spot on the frame.
By-Passing the G103 at the fender or do a deeper dive into a wiring (resistance) check on that ground.

This way you are eliminating 2 sources of possible failure points and only have Fuel Filter Clogged, Fuel Line Issues as far as pressure.
and
The Fuel Pump Control - via the Relay side - Power Feed to the pump

 

[Digbird1]

DOn't quote me for sure on the numbers But I think the manager the fuel pressure is supposed to be 12 and it's 2. But it's a nig drop in pressure.

 

[Digbird1]

I will say I am somewhat confused on this issue, but if they can get the pump to run by applying a ground (which ground) the Relay Ground? or Pump Ground?

Relay Ground - affects the Power Feed and is controlled by the PCM, so a power check at the Pump is it a constant (12 Volt) power, as a voltage drop, or fluctuating voltage will cause a low-pressure issue. (Pump not spinning fast enough)
The PCM also has to see (ignition - injectors) for that ground to get it to run.

Pump Ground - This will affect the pump motor as well and also cause a low-pressure if the pump is not spinning fast enough.

Fuel Pressure Regulator - I would have to dig in the manual to confirm, but this should be a mechanical (vacuum controlled) regulator. It controls the fuel pressure going to the Fuel Rail (Injectors)
A bad regulator would cause start / running issues, but it would not dump power at the pump.
A quick check (if vacuum) controlled is to pull the vacuum line and check it for fuel if fuel is in the line the diaphragm is blown in the regulator.

So, at this point just to see what the pressure is doing, is to check the fuel pressure at the rail and then compare that to the fuel pressure at the fuel filter connection

Basically this - The FPR lets the fuel pump build pressure from the volume output of the spinning pump, and it controls that pressure but does not affect the power / ground control for the pump.
This is one of the reasons I suggested, disconnecting the fuel line and have a bucket ready to catch the fuel. I wanted to see if the pump was actually not running.

Hopefully, they can pinpoint it down, but yes - I would shift focus to what is the pressure, possibly shot gun a regulator at it and then if still an issue, backtrack to (where are they applying the ground to get it to run) what circuit and then dig into a possible issue on either ground circuit.
From what I gather so far, and your latest post- I would say it's the Pump Ground not letting the pump to spin fast enough.
Which brings us back to the G103 - right next to the Starter Relay you replaced, which is where I strongly believe the ISSUE is as you were at this area and then the ISSUE started.

So, to eliminate factors here, I would shot gun a FPR and also cut the ground wire a few feet from the fuel pump connector and run a new ground to a good clean spot on the frame.
By-Passing the G103 at the fender or do a deeper dive into a wiring (resistance) check on that ground.

This way you are eliminating 2 sources of possible failure points and only have Fuel Filter Clogged, Fuel Line Issues as far as pressure.
and
The Fuel Pump Control - via the Relay side - Power Feed to the pump

This is over my head. The tech said it was like jumping the pump, it which case it would run whenevr the ignition was on.
My problem is finding a guy or a shop that knows this stuff. Is this something most experienced mechanics would be able to diagnose? The guy at the shop and the manager both admitted I should find someone more knowledgeable about an older vechicle. I'd hate to have to sell it for next to nothing because I can't find someone that's able to fix it.

 

[RangerBill]

My problem is finding a guy or a shop that knows this stuff. Is this something most experienced mechanics would be able to diagnose? The guy at the shop and the manager both admitted I should find someone more knowledgeable about an older vechicle.

This is what I was saying in a reply above that you took offense to. Any experienced mechanic should easily be able to find the problem. It sounds like a poor ground connection to the fuel pump motor to me.

 

[RangerBill]

When I swapped out the starter relay I remember there's two ground wires. I wonder if I may caused this issue myself by screwing up the ground. I don't understand what is meant by making a jumper to jumper the ground from the top of the fuel box. After installing the new pump my mechanic sort of ate his words and is bringing over a meter, a voltmeter I think. Thanks again for the help!!

Was the starter relay that you replaced located on the left fender apron? Were the two ground leads connected to one of the starter relay mounting screws? Are there two ground wires there now? The circuit diagram posted earlier shows the fuel pump ground connection on the top left fender apron center. I would double check your wiring done while replacing the starter relay.

 

[Jason B]

DOn't quote me for sure on the numbers But I think the manager the fuel pressure is supposed to be 12 and it's 2. But it's a nig drop in pressure.

If those are the readings, then it isn't enough. They should be around about 35-50 PSI IIRC.
When is the last time the fuel filter was replaced?
Also, on some engines (don't know about the '94, had it on a '99) there is a pressure regulator OR pulse damper on the fuel rail that's controlled by a vacuum line. If either are bad, you won't get the proper pressure.

 

[airline tech]

This is over my head. The tech said it was like jumping the pump, it which case it would run whenevr the ignition was on.
My problem is finding a guy or a shop that knows this stuff. Is this something most experienced mechanics would be able to diagnose? The guy at the shop and the manager both admitted I should find someone more knowledgeable about an older vechicle. I'd hate to have to sell it for next to nothing because I can't find someone that's able to fix it.

Just curious if you got the truck running yet?

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