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truck cranking but wont start

2K views 9 replies 4 participants last post by  tech10002 
#1 ·
i have an 04 f250 6.0 ford and its having a problem starting. it will fire up in the morning but then when its warm it wont start. i checked the codes and nothings coming up. i just changed the oil, checked the fuel filters, checked the batteries. i have no clue what else it could be. maybe air in the fuel lines?? someone please help. if it is air in the lines is there a way to drain the lines??
 
#2 ·
I know there's a pressure relief valve on the main fuel filter, not sure if that will solve your problem or since you already checked the fuel filters then I'm sure you used that valve. but maybe you forgot
 
#5 ·
ahhh, I see now. Your primary fuel filter is located on the frame under the driver side door. It has a hex head relieve valve on it where it will discharge the fuel thats in the pump/heater/filter/water separator. Chances are if you didn't know where that was, then you probably have a clogged fuel filter. Since its the first in line, it builds up most of the crud.
 
#7 ·
if you have a later built 04 6.0L then I would suspect you have a failing STC fitting on yoyur high pressure oil pump. they are known for starting fine cold, when the oil is thick, but when its hot and the oil is thin it wont have enough icp pressure to start. best bet is to monitor your icp prerssure when its hot and wont start. if your not at or over 500 psi it wont start.
 
#8 ·
no prob offroader. listen to the mastertech but for future reference your owners manual (the diesel book) has how to maintain your primary fuel filter. the valve is just like a spring loaded hex screw if I remember correctly. That opens up and relieves the pressure. Then, to be honest, I don't remember how to get the filter out, I think its just a simple twist thing..unfortunately I've had my truck in the shop for other repairs when my fuel filter replacement was due so for the last 30k+ miles I haven't done it. Only did it once myself since I owned it.
 
#10 ·
It's not quite as simple as that. As Mastertech said, most likely you have a failing STC (snap to connect) fitting on your HPOP (high pressure oil pump) that feeds the high pressure oil rails. The 6.0 and 7.3 Powerstroke use a unique fueling system that uses high pressure oil generated by the HPOP to drive hydraulic unit injectors. Just think of a heavy duty hypodermic syringe. The diesel fuel is the "medicine" and the high pressure oil is your finger pressing the syringe down.

The repair is pretty involved and will mean taking everything off the top of your engine to get down in the valley to make the repair. You can do it yourself, but you need to be a pretty skilled shadetree mechanic. The first step is getting the truck diagnosed to check your high pressure oil when it's cranking and go from there.
 
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