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2003 F 350.00 7.3 powerstroke. Truck has been having issues for several months. It idles fine but after running for 15 20 mins it losses power and shakes violently. The symptoms come and go. They are most notable when trying to accelerate or under load. To date I've replaced the fuel pump ipr icp head gasket (complete with wire to injectors and plugs) exhaust back pressure sensor fuel filter. Still has same issues. unglued icp the other day and it ran awesome for ten minutes then started bucking and loosing power. Anything else to try??
It has all the symptoms of low fuel pressure. Do you have a fuel pressure gauge you can plumb in and check fuel pressure at wide open throttle, under load?
Fuel pressure isn't in the data; there's no sensor on the engine. With the symptoms you've described, that's where I'd start though. There are test ports on the fuel filter housing, one is prefilter and the other is post. The post-filter port is low on the back of the housing, adjacent to where the fuel lines exit to go to the heads. It's a -4 ORB thread. There is also a test port on each head, with a pipe plug installed. The left head has it toward the back, next to the turbocharger compressor housing, and the right head has it toward he front near the A/C compressor. The head test ports are 1/8" NPT. A mechanical oil pressure gauge, or any 0-75 psi gauge for that matter, should work fine for testing.
Are you getting any codes, particularly a P1211 or other ICP related codes?
Yeah, time to get a fuel pressure gauge on it, for sure. Low fuel pressure causes excessive high pressure oil consumption and will trigger the P1211 because the HPOP can't keep up with demand. There are other things it could be, but fuel pressure is one of the most common causes, and easy to check.