Merc Mountaineer, no fuel pressure

mercury
mountaineer

#1

Hello all,

On my 2005 Merc Mountaineer AWD, I’ve had the fuel pump and fuel filter replaced, crankshaft sensor, ECM relay for the fuel pump, starter, and spark plugs replaced, but to no avail. Car starts when it wants to, but when it doesn’t, it’ll usually take three to ten minutes of cranking on and off before it fires up. Ford dealership and second repair shop confirmed no fuel pressure to the fuel pump when the vehicle doesn’t want to start and recommended a new fuel pump. Problem is, I’ve already paid the first repair shop for that same service and its gone back to them three times. Could this be electrical as the first shop is now claiming or are multiple mechanics missing something? Second shop replaced the ECM relay out of caution, but the problem persists. Thanks.


#2

Has anyone checked to see if the fuel pump driver module is functioning when trying to start the engine?

Tester


#3

Not sure I f theyve checked that. I am dropping it back off tomorrow and I will mention it. Thanks.


#4

Does it happen more often in hot weather?


#5

Car starts when it wants to, that is what I had. 1997 Mercury Mountaineer 5.0. It would always turn over but no spark depending on, well, nothing. Starting was totally random but once started ran great. Nobody could figure it out. No Check Engine, no codes. Happened more often when the weather got very hot, but still totally random. Finally diagnosed that there was no Crankcase Position Sensor signal getting to the PCM. That was not quite true, CKP signal was getting to PCM, but PCM was bad. Got a rebuilt PCM for $141.00, ten minute installation, been good ever since. Never had a more pain in the ass car problem than this one.


#6

@tester mentioned the driver. A bad crank sensor will also turn off the PCM to fuel pump.