tdek5462

I have an 04 F150 with a 5.4 3v with 200k and for a month a two it had a slight shake at idle and would occasionally throw lean codes but still drove fine and had power so I figured it was a vacuum leak and planned to address it soon. Well one day I was driving into the neighborhood doing about 30mph and the truck just died and would turn over but not start. I got help and towed it home. I had to crank for a while but it eventually started but idled with a horrible miss for about 1 minute or two then die. I decided to get carb cleaner and track down my vacuum leak so I knew that was definite problem. Figured it was the intake manifold gasket on the passenger bank that was shot due to oil leaking from the valve cover engine would stay running fine if I'd keep spraying carb cleaner near the leak. I ordered new gaskets for intake and passenger valve cover as well as new plugs and coils because it was getting close to the time to change them again. Got everything installed and went to start it it up and it did not fix the problems. I decided to check to see if I was getting fuel pressure next. I pulled the fuel line off the fuel rail and usually fuel flies everywhere but this thing was near dry so I figured I was not getting pressure. I could hear the pump running but it sounded weak so I figured I'd change the fpdm and the filter before the pump. Did that and the pump sounded a lot stronger but problems was still there. I am stumped! Could this possibly be a leaking fuel injector? If I get it to run for a little while it will miss and also backfire into the intake and then it will die and will be impossible to start again unless I wait like 30 minutes and keep hitting the key on and off to build up the fuel pressure. Any Suggestions would be greatly appreciated because I am getting tired of throwing money at it without fixing anything.

tdek5462

Also cleaned replaced maf and cleaned throttle body. I have also ruled out the possibility of jumping time because all time components and phasers were replaced with motorcraft parts about 10k miles ago

Mod (Ret.)

When was the last time the fuel filter was changed?

tdek5462

I just changed it a couple of days ago when I change the fuel pump drive module. Before that it had been a while since it was changed and it was long over due.

jkenprice1

Have you consiidered the coils.

Martian

Coils / plugs, foam around the air filter box, battery relearn, test fuel pressure on the rail in case you think the injector is leaking