Solved 2000 5.0 AWD wont warm Start without relieving fuel pressure at rail

[willyum727]

2000 Explorer XLT 5.0 AWD. Start and run cold no problem but if you get it warm and shut it off for 10 minutes or so it wont start back up for at least a half hour. If you shut it off and turn it back on right away it starts and runs with no problems. I have intermittent CEL that is the EGR. I accidentally happened to notice that if I have trouble starting if I hook up my fuel pressure gauge and relieve the pressure on the fuel rail it starts and runs immediately. WHAT CAUSES THIS???

I have replaced fuel pump, fuel filter, coolant temperature sensor, crankshaft position sensor and because of turning the motor and excessive number of times the starter and for good measure the battery.

 

[99SportX]

Hook up your fuel pressure gauge. Turn the key on and watch the pressure come up with the pump priming cycle. Shut the key off and watch the gauge. It should not drop much at all.

If your fuel rail damper is leaking, you will see the pressure slowly creeping down to zero. If the pressure holds for 10 minutes or so, you probably don't have a fuel problem.

It took me a long time to diagnose my leaking damper. I was always able to get it started by giving it a bit of throttle so i wasn't too motivated to find the problem. Lol

http://www.explorerforum.com/forums/showthread.php?t=351793

 

[willyum727]

Does the dampener prevent too much pressure from building in the fuel rail? I ask because when I have the problem warm starts I can relieve the pressure at the schrader valve and the truck starts right up.

If I hook up my fuel gauge it takes hours to lose pressure so I know its not leaking.

 

[koda2000]

the 2000 model has the fuel pressure regulator as part of the fuel pump assembly in the tank. it's job us to dump excess fuel pressure directly back into the tank. I'd be more inclined to think your problem may be there. the purpose of the damper (as far as I understand it) is to relieve pressure spikes and dips.

you stated you replaced the fuel pump. did you replace just the pump part, or the whole assembly?

 

[willyum727]

I only replaced the pump however I ordered a whole assembly this morning. Ill update if the problem is resolved after I replace the whole assembly. I wasnt aware that the regulator on the assembly would also relieve pressure in an engine off situation.

 

[willyum727]

Replacing the whole fuel pump assembly appeared to be the solution.

Thanks guys.

 

[Turdle]

Replacing the whole fuel pump assembly appeared to be the solution.

Thanks guys.

Thanks for posting an update. I marked this thread solved to help others.