Ok, so the Pt is a 2002 4.6L Extended Cab Lariat, 310,000 miles

I need help figuring out why this truck is consuming fuel pumps like they are going out of style (4 in last 2.5 months), I am getting tired of taking the bed off all by myself, neighbors prob think I crazy.

So, to give a little background the factory fuel pump went out (I thought) in 2021 (260,00 miles), I put a new FP, Filter and Fuel regulator in and still couldn't get the pump to run, after much scratching my head found it was a slightly corroded connector pin in C192 in circuit #238 (DkGrn/Yel wire from FP relay to inertia switch)

FFwd to Mid-October of this year (4 yrs later) it died sitting at a light, wouldn't start...no fuel pressure. Had it towed home, figured the AutoZone (Chinese) FP I put in it 4 yrs ago was prob past its lifespan, I took the bed off and replaced the pump, presto! back in business ran great!
FFwd to Mid-November (1-month later) went out to go to the store...Cranks/no start...no fuel pressure...
Did some research on premature Fuel pump failure found 4 main reasons

1. Low voltage
2. partially obstructed line/filter
3. faulty Fuel Pressure regulator
4. Running on empty all the time (overheating)

AARRRGGHH, thought "I didn't change the fuel filter the last time, pump must have sent shrapnel into filter when it failed?"
Just to be safe, I also traced down each connector in the circuit all the way back to the fuel pump, inspected each for corrosion and tested each segment of wire for continuity and was able to get 12v through each segment without any drop.
Put another new Pump and also changed the filter this time. Good pressure ran great. New air filter also

FFwd to 2 weeks ago (2 weeks later), truck started throwing codes PO171 (lean Condition in Bank 1) & PO174 (lean condition in Bank 2), then it died on me driving home from work (no fuel pressure again), had it towed home again.

• Removed bed & pulled the pump again,
• Put new pump into the assembly and tested before installing (12v applied to connector (C463))
  • pump would not run,
  • tested again at pigtail on assembly, pump ran.
  • Checked for continuity on red wire between C463 & pigtail to pump...none.
  • Purchased new assembly and installed
  • Ran great, good Fuel pressure (34 psi @ idle)
• Still throwing PO171 & PO174
• Tested Fuel pressure Regulator
  • At Idle (34 psi)
  • Removed vacuum line to FPR, pressure increase approx. 10 psi
  • Re-Applied vacuum, pressure dropped back to 34 psi
  • Throttle response (with vacuum applied), pressure increased 6-10 psi
  • Never any unexpected drop in fuel pressure

Tonight, went out to go to work....No Start///NO Fuel pressure again!!!!

Each time before taking off the bed and pulling the pump I disconnect the harness at C463 and apply 12v (via power probe) to see if it will build pressure...each time I get none... I will do the same in the morning.
I have inspected the inside of the tank it is always bright silver (no rust) inside, and no visible sediment anywhere (looks brand new inside).
Screen at pump intake is always clear of any sediment or debris.
I have been noticing "knocking" when accelerating uphill (figuring this is due to the lean condition)
No other noticeable performance issues until the absence of fuel pressure.
I have a very rudimentary scanner (innova) from AutoZone, was able to pull the following data from the PO171 code (not sure if this is a freeze frame of when the code imitated, or at idle. But numbers were not fluctuating telling me it wasn't live data)

• Calc Load = 78.8%
• ECT = 169 F
• STFT B1= 9.4%
• LTFT B1 = 25.0%
• STFT B2 = 6.3%
• LTFT B2 = 21.9%
• Eng RPM = 1052

I know those total fuel trims are high (34.4% in Bank-1, 28.2% in Bank-2), but is that enough "extra fuel" to burden the pump into premature failure?


I intend to do a Voltage drop test to the circuit, but I have to have a working pump in there and have enough time to do the test (I rarely have the time to do the test, I always have to get it back together ASAP so I can get to work....last pump install was finished up out in the street in the dark at 10pm),I'm no mechanic, I just try to keep my stuff running...this is really frustrating me....feel like rolling this thing off a cliff at this point. I'm 57yo and taking that bed on and off by myself is daunting and leaves me sore for a day or two.

Any help would greatly be appreciated

​​​​​​​Thanks

 

Update on likely cause of elevated fuel trims.
I was looking over things this morning and found the rubber plug where the wires pass through to the MAF sensor was dislodged I re-inserted it, I'll have to see when I get it back running if that was the cause of the lean condition.
This likely happened when I was checking the connectors underneath the air filter housing.
This would likely not be a contributing factor to my premature Fuel pump failures, since this work was done after the 2nd pump replacement.

So, I still need help figuring out the reason my Fuel Pumps keep failing (the last one lasting less than 400 miles)

Thanks