I am having problems with starting my truck for the last few months. When I turn the key, the truck doesn't start. It can take several times to turn the engine over. Other times, it start right up. The starter turns and it sounds like it is getting sparks, but lacks fuel.

It's a 2001 4.6L V8 4x2 Supercrew.

I have checked the fuel pressure on the fuel rail. It holds at the lower limit of the spec at idle, increases a little when accelerating but drops off rapidly to 0 when turned off. Based on the diagnostics I have read, I have replaced the fuel filter, the fuel presure regulator on the fuel rails, have used a variety of fuel system cleaners (Heet, techron, Seafoam, etc). I do not smell any gas from a leak in the lines.

The presure drop off still occurs when the engine is turned off and I still have problems starting the truck from time to time.

I have checked the fuel injectors to see if they leak under presure when the key is turned on, but haven't found any leaks. The PCV valve seems to work and has good vacuum. I don't receive a service engine soon light.

I have replaced the starter motor and battery for other reasons this summer. I change the oil and filter and perform other such maintance at regular intervals.

I don't know if this is a related symptom, but a whine is heard sometimes when starting up and running. It usually goes away when I acclerate, but sometimes return while driving.

My question is, what else could be causing my problems, a bad fuel pump? What else should I check?

Thanks in advance

 

have you had the pressure gauge on it while the truck is off and see if it leaks down or not?

 

Do you have any hesitations or problems when driving, or seems like lack of power. Sometimes a bad catalytitic convertor will gives symptoms of a fuel problem

 

Matt's Ford,
Yes, I've had the pressure gauge with the truck off. It doesn't hold pressure when off. It bleeds off to 0 rapidly.

2006M50B,
Yes, sometimes it shudders and hesitates right after starting, but not all the time and not after every start. Power and fuel efficency don't seem to be what it used to have, but it is older. How do you check a cat convertor?

 

As you obviously know, the fuel pressure shouldn't rapidly drop off to zero when the pump stops. About the only thing you haven't covered in your search is the fuel pump. there is a check valve in the pump to keep the pressure from dropping off. Other causes are leaky injector(s), hole in fuel line, bad regulator - all of which you've already covered. How did you check the injectors? The only ways I know are by pulling the plugs after repeated pressurization cycles to see if any are wet, or by removing the fuel rails, injectors still attached, and turning on the key (can be messy if they leak).

 

06 So Comfort,
For checking the injectors, I followed a procedure listed on this forum, your second method listed. I disconnected the wires to each injector, loosened the fuel rails and lifted the assembled fuel rails and injectors above the engine, then turn the ignition on to pressurize the system and look for leaks. I did this a few cycles without seeing or smelling any leaks.

For the fuel pump, I assume I have to drain and drop the fuel tank, then disconnect the fuel pump for testing. I didn't want to do this initially. Is there any way to test the check valve/fuel pump assembly in place?
For the fuel pump, I assume I have to drain and drop the fuel tank, then disconnect the fuel pump for testing. I didn't want to do this intially. Is there any way to test the check valve/fuel pump assembly in place?

 

No in-tank tests that I know of, other than process of elimination. It really isn't that bad a job, if you have a helper to steady the tank while you lower it with a floor jack. The trick is to have the tank as near empty as you can - gasolene is heavy. the fuel pump itself isn't real expensive - usually <$150.00

 

you could also pick the bed up off the truck. its easy access or you could jack up 1 side of the bed with a jack and a good size piece of wood. i dont know how many bolts or wires you would have to undo if you were to do this but mine was just 6 bolts and 1 plug in the very back under the middle of the tail gate. this is just an option not saying its the better way. but you dont have to undo everything and worry about kinking and breaking all the lines hoses and wires.

 

If it was the cat the problem would be ongoing and not sometimes-but to answer your question of how to check it
-easy way is to look at it after been running awhile, if its really clogged it may be glowing red (doesnt always work)
-another way is to remove the cat from the system or disconnect the pipe just before the cat
-do you have a sulfer smell at the tail pipe, thats another good indication

another possibility, is maybe the coolant temp sensor is bad. Had one go out on my E150 van, when cold wouldnt start and when it was warm it started but seemed to have lack of power. If sensor is bad it gives the computer bad info for how much fuel to send so you run super rich or lean-just another idea

 

Matt/SO Comfort,
I will check the fuel pump when I get a free weekend and have some help around.

2006MSB,
Probably not the cat then, as no sulfur smell or other odd odors.
When you coolant sensor went bad, how did you test it? Did you get any engine codes?