My 05 F150 5.4l 3v with almost 190,000 miles started acting up a few days ago. Cranks over but took it a few seconds and noticed a lack of power on the highways won't go over 80mph. Now the truck still cranks over but won't start on the first attempt but fires right up on the second attempt with no hesitation. It will start right up when the engine is warm but won't when it's cold. Tested fuel rail pressure with my Blue Diver OBD 2 scanner when the engine was cold, I just turned the on position and it only reads 2-3 PSI. Once the truck is running it reads between 36-43 PSI. Truck drives just fine other than trying to go over 80mph.
I went ahead and replaced the Fuel Pump Driver Module with no changes, and I am currently still driving it just trying to get the fuel tank a low a possible. Just assuming it's a fuel pump at this point and I bought a new pump and filter. Any other suggestions would be great don't really want to replace the pump.
Also, no codes
Thanks
I will refrain from commenting on the wisdom of wanting to drive a 20-year-old, high-mileage pickup truck at over 80 mph...
Tested fuel rail pressure with my Blue Diver OBD 2 scanner when the engine was cold
Your fuel rail appears to be losing pressure when the engine is off. There is a check valve that is supposed to prevent that in order to facilitate faster engine starts. It may be in the fuel pump assembly or may be a separate part somewhere in the fuel system.
Once the truck is running it reads between 36-43 PSI
That is within specification but should be verified with a mechanical pressure gauge directly on the fuel rail rather than trusting a 20-year-old sensor reporting the pressure to a scan tool. Also the pump needs to deliver enough fuel volume as well as pressure.
Just assuming it's a fuel pump at this point and I bought a new pump and filter.
It's best not to assume anything or load up the parts cannon, that rarely works. Further diagnosis is needed. You might start by checking live data if that has not already been done, and recording a live data session when attempting to drive the truck at high speed. You could check for excessive back pressure in the exhaust system. There is also low-hanging fruit such as filters and spark plugs.
You can find a repair manual for your vehicle at the link below:
Truck drives just fine other than trying to go over 80mph.
You shouldn't be driving trucks at that speed in the first place -it's unsafe. My old Ranger was governed to 85 MPH and I would feel like I was sailing if I went that fast. Pickup trucks aren't sportscars and should never be driven like that. Pickups have a high center-of-gravity, and can easily tip over if you need to suddenly take evasive maneuvers. If you want to drive fast, get a sportscar or a sedan.
