I have a 2003 F150 with the 5.4L. the last month or 2 it has been giving me problems with starting. i can hear the pump prime most times but it will not always start, there are times that it wont prime and it wont start. it will just crank and crank then try to start but it will die before it really gets running kind of like it is flooded. if i cycle the key that sometimes help and i can hear the pump prime and it starts but that is becoming few and far between for temporary fixes. the problem has been getting worse and worse. I have replaced the fuel filter and checked the module that kills the pump in the case of a front end collision but that is all. I have searched the online forums and found a lot of people that have had this problem but there are not any solutions. I recently read about a shrader valve but don't have a very good understanding of it. Could this be my problem, what does the valve do. I don't believe the the fuel pump is bad as it starts intermittently and will run strong no stalling or rough idle in town or on the highway. Thanks in advance.

 

Fuel Pump is bad. Your description points right to it. It's how they go out and common. Surprised you haven't found that. The fix is a new pump, that one is freezing up on yuh.

Easy to replace with basic tools.

You can borrow a pump pressure tester for free from auto zone (free loaner program). Check the pressure.

You say the pump isn't always charging the lines upon start. Leave the key on and hit the tank with something. Chances are it will free up momentarily.

 

I find it hard to believe that its the fuel pump. In my experience they don't just come and go they either work or they don't if they are getting weak then there are symptoms that point to a bad fuel pump. I can hear the pump prime and it still wont always start. that's why I am curious about the shrader valve if it is leaking then there wont be pressure at the fuel rail. I don't fully understand the shrader valve as near as i can tell its for pressurizing or depressurizing the fuel system, but if it is leaking how much is it leaking to cause the system to not pressurize .

 

Like I said, A simple pressure test will confirm. Easy peasy. You asked, don't fight it lol.

 

Dont get me wrong i appreciate your help i guess im just frusterated as i had to have it towed today making me late for work and blah blah im sure you have heard the story. do you happen to know what the pressure should be off the top of your head. I will have to do the pressure test tomorrow I love the auto zone free rent a tool program saves me a ton of money.

 

Well Ford calls it good as low as 28 psi depending on some of these engines. Personally I've never seen a good pump test below 32 psi on the crank. They begin having their freezing fits at 32 psi and below.

Normally, a healthy pump will be at 34 -38 psi. When they get as low as 32 psi, it's an any time now type deal.

You can pretty much follow procedure when checking pressure. I believe even Chilton/Haynes got that one right, that's saying a lot for those manuals.

If you plan on keeping the truck for awhile, it's a good idea to purchase a Ford Service CD/DVD that covers your vehicle. You can pick them up on e bay, maybe A mazon as well. Before purchasing one, run it by us first. Yea, there's knock-offs out there.

 

As Jbrew said classic fuel pump problem.

 

thanks man i will be doing that in the morning its really going to p*** me off if its the fuel pump i have been racking my brain trying to figure this out i really hope i wasnt blinded by my own thinking anyways thanks again and sorry if i came off as an a**hole.

 

Well good luck. Great group of guys around here that undeniable know how these trucks running at there best.

Let us know what your find.

 

Same exact thing happened to my truck last week - 97 f150 4.6 with 170,000 miles

IT WAS DEFINITELY THE FUEL PUMP - no problems since.
Sometimes you can hear the pump prime and sometimes you cant. I made sure i had 12 volts to the shutoff switch behind the kick panel.Tell tale sign was that fuel pressure was very low.

Yes - the pump can fail intermittently its very common with these. Get one from rockauto - replace the whole sending unit is the easiest way.