Hello fellas. New to the site. I have a 2001, 4.6 F150 4x4 with 130,000 miles on it. Last Month, just out of left field, my truck became hard to start. It will just crank and won't fire. Seems like it is not getting fuel. You can keep trying and turning the key on and off and eventually it will fire (so far). Since then, I have done a lot of research as to what the problem could be (check engine light is not on). I replaced the IAC (idle surged sometimes), cleaned the MAF sensor, cleaned the throttle body, replaced the cylinder head temp sensor (does not have the engine coolant temp sensor), put on a new battery...still have the problem. Yesterday I got in the truck to start and noticed this....I turned the key forward and didn't hear any "noise". The truck spun over and seemed like it wasn't getting fuel. I turned the key off and back on...I heard a "hum" for like a second...maybe some kind of relay (it seemed like it was under the hood) and it fired right up. Is the 1 second "hum" the fuel pump (and it just sounded like it came from under the hood) or is there some kind of relay I need to check under the hood? Anything else I would need to check? I have access to a fuel pressure gauge if need be. Thanks in advance.

 

Check your fuel pressure, then go from there if it is acceptable.

 

Him is fuel pump running to pressurize fuel rail.

When engine won't start immediately, but does after a few seconds of allowing this fuel pump to run then the check valve has leaked off pressure while it was not running. Not a big deal.

But if it struggles to start a lot even after leaving the key on for a few seconds then likely the fuel pump is bad or flow restricted or regulator bad.

 

Update... Friend has not brought fuel gauge to work yet so I worked on it some tonight. Changed fuel filter (made sure it is going in the correct direction). It started right up. I shut it off after about 4-5 seconds and went to restart. Started fine but began to idle funny....it then died. Like it was starving for fuel. Restarted it and it ran fine for a few seconds then the same thing. Already had a fuel pump relay, so after breaking the tab off the box by just opening it, I replaced it. Hooked up battery and it will turn over and act like it wants to start, but it just dies. Depressed the Schrader valve on the fuel rail and had plenty of fuel. Removed the fuel pump regulator (plenty of fuel there too) and installed new one. Lost the friggin lock ring somewhere trying to put it on. Have to wait to get ring before I try again. Ready to put rag in tank and have a bonfire!!! lol