03 6.0 High Fuel Pressure? - Ford Powerstroke Diesel Forum
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post #1 of 2 Old 01-13-2014, 12:50 PM Thread Starter
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03 6.0 High Fuel Pressure?

Guys, new to the forum and have been reading along but this is my first post.

I have an 03 F250 Super Crew Lariat with a 6.0L and 150,000 miles. Owned since new and have treated her well. No aftermarket mods or anything else. Ficm repaired a year ago and repair solved the issues I was having. Regular oil changes with Rotella and an occasional dose of hot shot.

Had a bad fuel injector on #6 about 4 months ago which I had replaced along with all the other injectors on the drivers side which were running below 90%.

Anyway, Driving home from VT after the new year doing highway speed and just like someone flicked a switch, started loosing power. Had to exit right away and she was smoking quite a bit. As I exited, she would idle but had little or no power. Press the pedal down and she would stumble and smoke. She would sit and idle fine but ended up having to have it towed.

Got her home to the driveway on a flat bed. The driver of the flat bed turned on the ignition to put the transmission in neutral. As the truck rolled down the flat bed, I noticed a fuel puddle directly under the on frame fuel pump. Thought it was odd and when I got it off the truck, did not find where it might have leaked. Took the pump off and it tested ok and seemed to pump fuel ok.

When I reinstalled the pump, I primed the system and attempted a start. The truck would try to start and run for about 2-3 seconds before quitting. It repeated this several times.

I am not getting any fault codes and do not have a scanner that would tell me what the HPOP is doing.

I removed the cap on the on engine fuel filter and when I did, I noticed something odd. Pressure blew out of the cap when I started to remove it. Also found evidence of an O ring failure on the return line on the fuel pressure regulator return line to the tank. When I cycled the key one more time while looking at the cap(which was firmly screwed down), fuel blew right past the o-ring seal and I imagine this is what happened at the rail mounted fuel pump.

So, I am thinking that the rail mounted fuel pump is either blocked or the pressure regulator in it (Max 100psi I think) is bad. Fuel pressure is getting too high.

Symptom wise, without a scanner, the truck seems to sound like a failure of the HPOP. Possible as well but what I cannot understand is why I am seeing such high fuel pressure and with these symptoms, would the engine behave this way if it was not an oil pump failure?

Thanks in advance for any input/advice

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post #2 of 2 Old 01-14-2014, 02:05 PM Thread Starter
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No ideas? I am assuming when the key is cycled that the fuel is pumped up to the on engine fuel filter and if there is a no start, the fuel returns to the fuel pump and or fuel tank. I am thinking that since the fuel simply pushes past the O rings on both the fuel pump and fuel filters that the rail mounted fuel pump must me over pressuring the fuel in excess of the 100 PSI max the pump is supposed to put out.

There is a fuel pressure regulator inside the frame mounted fuel pump that controls the fuel pressure. I am thinking this regulator is blocked or NG so the the fuel pump is pumping fuel with no relief.

It would explain the fuel smell I was getting on random occasions before the trip to VT.

I have ordered the blue spring pressure regulator upgrade and will install that along with pulling the pump for another look at the fuel return.

Something is just not right...

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fuel filter , fuel pressure regulator , fuel pump

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