2007 F150 Lariat 5.4L Fuel pump driver
06-30-2024, 03:54 PM
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2007 F150 Lariat 5.4L Fuel pump driver
Hello everyone. Use this site all the time and just had to ask a quick question. I had the FPDM failure with code p0191 and replaced with Dorman originally. Worked for a while then started to randomly lose fuel pressure so replaced with another since it was still under warranty. Same issues began again so I tested fuel pump. When bypassing FPDM I have 78psi on fuel system. Checked all wires for FPDM and fuel pump for continuity and replaced ground wire at FPDM. Then checked continuity on signal wires from FPDM to PCM. Everything checked out there. Visually checked connectors along frame under drivers door. Didn't notice any broken wires or burnt connectors. At this point I tried a fuel filter and FRPS. Didn't seem to help. At this point I had the p0191 and p1233 codes. Assuming it was the Dorman FPDM that was the issue I replaced with a Motorcraft FPDM. When I first tried to install Motorcraft module it wouldn't even send power to the fuel pump but the Dorman would at least allow pump to prime. At this point I grabbed a torch and was very seriously considering lighting the spare on fire underneath the truck. Cooler heads did prevail and I began testing procedures again. During my tests with the new Motorcraft FPDM I stumbled upon something that has me baffled. With the new Motorcraft FPDM plugged into the truck but NOT mounted on the frame, the truck will start and run fine. As soon as it makes ground contact with frame I can hear the fuel pump shut off and it begins to lose fuel pressure. Then if it is removed from frame the pump kicks back on and pressure rebuilds. With it dangling and plugged in I have between 38-42 psi while running and showing pump operating at ~17%. When it touches frame it goes to 75% and pump shuts off. The issue is for the life of me I cannot figure out if this is a ground issue or short issue or PCM issue. Any help would be greatly appreciated. Thank you.
06-30-2024, 04:54 PM
#2
Hello everyone. Use this site all the time and just had to ask a quick question. I had the FPDM failure with code p0191 and replaced with Dorman originally. Worked for a while then started to randomly lose fuel pressure so replaced with another since it was still under warranty. Same issues began again so I tested fuel pump. When bypassing FPDM I have 78psi on fuel system. Checked all wires for FPDM and fuel pump for continuity and replaced ground wire at FPDM. Then checked continuity on signal wires from FPDM to PCM. Everything checked out there. Visually checked connectors along frame under drivers door. Didn't notice any broken wires or burnt connectors. At this point I tried a fuel filter and FRPS. Didn't seem to help. At this point I had the p0191 and p1233 codes. Assuming it was the Dorman FPDM that was the issue I replaced with a Motorcraft FPDM. When I first tried to install Motorcraft module it wouldn't even send power to the fuel pump but the Dorman would at least allow pump to prime. At this point I grabbed a torch and was very seriously considering lighting the spare on fire underneath the truck. Cooler heads did prevail and I began testing procedures again. During my tests with the new Motorcraft FPDM I stumbled upon something that has me baffled. With the new Motorcraft FPDM plugged into the truck but NOT mounted on the frame, the truck will start and run fine. As soon as it makes ground contact with frame I can hear the fuel pump shut off and it begins to lose fuel pressure. Then if it is removed from frame the pump kicks back on and pressure rebuilds. With it dangling and plugged in I have between 38-42 psi while running and showing pump operating at ~17%. When it touches frame it goes to 75% and pump shuts off. The issue is for the life of me I cannot figure out if this is a ground issue or short issue or PCM issue. Any help would be greatly appreciated. Thank you.
06-30-2024, 05:05 PM
#3
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First let me say thank you a great description of your efforts and the problem.
Did you buy the new Motorcraft FPDM from a Ford Dealer? There are counterfeit parts out there.
I have a question concerning your statement "and replaced ground wire at FPDM". Please provide detail as to what was done withe the ground wire and is connection. There was a recent posting where the problem appeared to be the the ground connection stud for the FPDM was corroded to the point that it was not consistently making a good ground. Here is a little more detail - the FPDM had been replaced and the ground connection moved to the stud(s) that hold the new FPDM from its original connection point on the frame. Using the studs caused him a problem that required to studs to be removed, cleaned and reinstalled solving his problem. Take a look at the following posting (its a long one) for all of the details but the bottom line is that the as designed connection point on the frame is a more reliable connection point for the ground wire than the studs that hold the FPDM to the frame. It took 17 days and much head scratching to solve that problem
https://www.f150forum.com/f4/2005-fu...ispreloading=1
See post #19 and #31
The fact that you have tried multiple FPDMs with varying results sort of points something else, likely a ground wire issue that is making this a mystery.
Did you buy the new Motorcraft FPDM from a Ford Dealer? There are counterfeit parts out there.
I have a question concerning your statement "and replaced ground wire at FPDM". Please provide detail as to what was done withe the ground wire and is connection. There was a recent posting where the problem appeared to be the the ground connection stud for the FPDM was corroded to the point that it was not consistently making a good ground. Here is a little more detail - the FPDM had been replaced and the ground connection moved to the stud(s) that hold the new FPDM from its original connection point on the frame. Using the studs caused him a problem that required to studs to be removed, cleaned and reinstalled solving his problem. Take a look at the following posting (its a long one) for all of the details but the bottom line is that the as designed connection point on the frame is a more reliable connection point for the ground wire than the studs that hold the FPDM to the frame. It took 17 days and much head scratching to solve that problem
https://www.f150forum.com/f4/2005-fu...ispreloading=1
See post #19 and #31
The fact that you have tried multiple FPDMs with varying results sort of points something else, likely a ground wire issue that is making this a mystery.
06-30-2024, 05:26 PM
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First let me say thank you a great description of your efforts and the problem.
Did you buy the new Motorcraft FPDM from a Ford Dealer? There are counterfeit parts out there.
I have a question concerning your statement "and replaced ground wire at FPDM". Please provide detail as to what was done withe the ground wire and is connection. There was a recent posting where the problem appeared to be the the ground connection stud for the FPDM was corroded to the point that it was not consistently making a good ground. Here is a little more detail - the FPDM had been replaced and the ground connection moved to the stud(s) that hold the new FPDM from its original connection point on the frame. Using the studs caused him a problem that required to studs to be removed, cleaned and reinstalled solving his problem. Take a look at the following posting (its a long one) for all of the details but the bottom line is that the as designed connection point on the frame is a more reliable connection point for the ground wire than the studs that hold the FPDM to the frame. It took 17 days and much head scratching to solve that problem
https://www.f150forum.com/f4/2005-fu...ispreloading=1
See post #19 and #31
The fact that you have tried multiple FPDMs with varying results sort of points something else, likely a ground wire issue that is making this a mystery.
Did you buy the new Motorcraft FPDM from a Ford Dealer? There are counterfeit parts out there.
I have a question concerning your statement "and replaced ground wire at FPDM". Please provide detail as to what was done withe the ground wire and is connection. There was a recent posting where the problem appeared to be the the ground connection stud for the FPDM was corroded to the point that it was not consistently making a good ground. Here is a little more detail - the FPDM had been replaced and the ground connection moved to the stud(s) that hold the new FPDM from its original connection point on the frame. Using the studs caused him a problem that required to studs to be removed, cleaned and reinstalled solving his problem. Take a look at the following posting (its a long one) for all of the details but the bottom line is that the as designed connection point on the frame is a more reliable connection point for the ground wire than the studs that hold the FPDM to the frame. It took 17 days and much head scratching to solve that problem
https://www.f150forum.com/f4/2005-fu...ispreloading=1
See post #19 and #31
The fact that you have tried multiple FPDMs with varying results sort of points something else, likely a ground wire issue that is making this a mystery.
FPDM ordered at Ford OEM Parts.com
06-30-2024, 05:31 PM
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First let me say thank you a great description of your efforts and the problem.
Did you buy the new Motorcraft FPDM from a Ford Dealer? There are counterfeit parts out there.
I have a question concerning your statement "and replaced ground wire at FPDM". Please provide detail as to what was done withe the ground wire and is connection. There was a recent posting where the problem appeared to be the the ground connection stud for the FPDM was corroded to the point that it was not consistently making a good ground. Here is a little more detail - the FPDM had been replaced and the ground connection moved to the stud(s) that hold the new FPDM from its original connection point on the frame. Using the studs caused him a problem that required to studs to be removed, cleaned and reinstalled solving his problem. Take a look at the following posting (its a long one) for all of the details but the bottom line is that the as designed connection point on the frame is a more reliable connection point for the ground wire than the studs that hold the FPDM to the frame. It took 17 days and much head scratching to solve that problem
https://www.f150forum.com/f4/2005-fu...ispreloading=1
See post #19 and #31
The fact that you have tried multiple FPDMs with varying results sort of points something else, likely a ground wire issue that is making this a mystery.
Did you buy the new Motorcraft FPDM from a Ford Dealer? There are counterfeit parts out there.
I have a question concerning your statement "and replaced ground wire at FPDM". Please provide detail as to what was done withe the ground wire and is connection. There was a recent posting where the problem appeared to be the the ground connection stud for the FPDM was corroded to the point that it was not consistently making a good ground. Here is a little more detail - the FPDM had been replaced and the ground connection moved to the stud(s) that hold the new FPDM from its original connection point on the frame. Using the studs caused him a problem that required to studs to be removed, cleaned and reinstalled solving his problem. Take a look at the following posting (its a long one) for all of the details but the bottom line is that the as designed connection point on the frame is a more reliable connection point for the ground wire than the studs that hold the FPDM to the frame. It took 17 days and much head scratching to solve that problem
https://www.f150forum.com/f4/2005-fu...ispreloading=1
See post #19 and #31
The fact that you have tried multiple FPDMs with varying results sort of points something else, likely a ground wire issue that is making this a mystery.
FPDM ordered at Ford OEM Parts.com
06-30-2024, 05:38 PM
#7
Senior Member
It might be an interesting exercise to take both the new FPDM and old one and probe each pin one by one for continuity with the metal housing.nsee if one is different than the other.
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06-30-2024, 09:43 PM
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I do not have the original Motorcraft FPDM but when comparing the Motorcraft FPDM I ordered and the Dorman one, there is some level of continuity between 4 of the 6 pins and the housing on the Motorcraft unit but none of the pins on the Dorman unit.
06-30-2024, 09:48 PM
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06-30-2024, 11:57 PM
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I have to think that's not a good thing. I have a spare ford module in my garage I can do the same test on tomorrow