Hi Scotty,
Really enjoy your posts and always very informative. My question is related to a fuel pump issue i have on a 2004 Ford F250 5.4 Crew cab. I changed out my fuel pump with an after market part because the Motorcraft part is scarce , the Delphi seemed to be an acceptable option. The reason i changed the part was the truck would just die while driving and no code was present. I had plenty of ignition just no fuel and this was intermittent . Changed the part and everything was great for two weeks and the it died again . I was told to change the Fuel Pressure Control Module and after looking hi and low , i was told I didn't have one.
One mechanic said I should stick to OEM and buy the Motorcraft pump and that should solve the problem, I'm just stumped! This has been a great truck with 250k miles on the motor, transmission with out issues. I've maintained the truck religiously .
Any advise ??
You're right. Your 2004 5.4L F250 doesn't have a FPDM. (The F150's did).
1st, listen to hear if the fuel pump is running for a couple of seconds when you turn the key ON during this No Start condition. (it would be interesting to see if you put power and ground to the old fuel pump ((which you removed)) if it worked).
What's interesting is that the truck ran fine for 2 weeks after replacing the fuel pump and then it was back to its old tricks again.
This is an intermittent issue which persists after a brand new part was installed and that always makes me suspect a circuit issue.
If you don't hear the fuel pump running for a couple of seconds when the Key is turned to ON then it's time to figure out "why not?"
Here's the circuit.
Power comes from Fuse 40 (20 Amp) in the fuse box to the Load Side of the fuel pump relay.
It exits the fuse box through a Dark Green wire w/Yellow stripe and goes to the Inertia Fuel Shutoff Switch.
It exits the Inertia Switch through a Pink wire w/Black stripe and provides battery power to the Fuel Pump Motor.
So if the pump isn't kicking on, the easiest thing to do would be to test the Fuel Pump relay socket terminals to see if the PCM is providing Ground to energize the relay's coil and if the other 2 Power inputs were present. But I'm pretty sure that you don't have a replaceable fuel pump relay so you can't pull it out and test the sockets.
You can check that 20A fuse.
At the risk of this becoming another one of my trademark "Long-Winded" replies, don't try to stop me now, I'm on a roll.
The other day a forum member asked an interesting question.
The guy wanted to know, when using his multimeter, when he should test for resistance as opposed to when he should test for voltage drop. This is a good example of when to test for voltage drop.
For a couple of reasons. First, this circuit is protected by a 20A fuse . It has heavier gauge wires (more wire strands in the wire to support the circuit).
Also it's an electric motor circuit. (again, larger current draw).
Second, the harness side wires to the fuel pump are under the vehicle (a rough environment). Any place the wiring insulation could have been "scuffed through" is an invitation for corrosion to form on some of the wire strands inside that wire (voltage drop).
So, if the fuel pump doesn't run for a few seconds, you can check for battery voltage with a multimeter by disconnecting the fuel pump connector and, at the Harness Side of the connector, check for battery voltage during those first couple of seconds with Key On (Pink wire w/Black stripe). ((DC Volts, 20 volt setting))
If you don't see battery voltage there, you can work your way upstream in the circuit and see where you're losing it.
If you do see battery voltage there, it tells you that your fuel pump fuse, relay and inertia switch are good and that the PCM is energizing the fuel pump relay by providing the ground to the control side.
It's time to test for voltage drop in the wiring.
Reconnect the wiring connector to the fuel pump.( you have to test for voltage drop while the circuit is under load).
I looked at your fuel pump and it has a pretty long harness. You should be able to get to it for this.
You'll want to "backpin" that Pink w/Black stripe wire on the Fuel Pump side of the connector and again, measure the voltage during the 1st couple of seconds when the Key is turned to ON and the circuit is energized.
You want to see nothing more than a couple tenths of a volt lower than battery voltage.
Your long-winded answers should be compiled into a book!
Great stuff.
Thank you , that was very informative and detailed , unfortunately that's all out of my wheel house.
I did have a mechanic hook up his Snap-on reader to the truck yesterday and he told me the PCM wasn't communicating with the pump so i'm guessing that falls into what you've recommended.
He told me I could try replacing the Delphi pump with a OEM pump (which has been difficult to find) or replace the board as the relay isn't removable.
I haven't been thrilled with my local Dealer so I may have to just find a knowledgeable mechanic and see if he can pinpoint the problem.
Thanks again.
I would try replacing the fuel filter if it wasn't done with the new fuel pump first. Your truck has a fuel pressure regulator. It could also become clogged and possibly cause your problem. It seems unlikely that a new fuel pump would exhibit the same symptom as the old one.
If you have a scan tool you should be able to read/monitor your fuel pressure, like before and after a new fuel filter for example. If you're not having a fuel delivery issue the scan tool will be most helpful in diagnosing what's wrong. When you own a Ford with that age and mileage a basic scan tool is indispensable based on my experience.
Replace the fuel filter and then pressure test the fuel pump. The new pump might already go bad.
I would measure the fuel pressure with a gauge.
Thanks for the link, Yeah i'm beating my head against the wall with this problem. It seems after it sits for a a couple of days it just starts and runs great . I just let it idol daily until it died out and would start, i figured that would give me a chance to check the fuel filter to see if the line was dry. I'll order this part and hope that fixes the problem.
you're beating your head because you're just throwing parts at it.
Diagnose.