Hpop???

[under pressure]

Can you tell me what the purpose of the HPOP is? Does anyone have a schematic or a decription of the function of a fuel system? What tells the injectors to fire? I have been chasing some problems for a few weeks now and the problems just keep changing. I used to be able to hear the injectors click when the fuel pressure got to 40PSI. Now they don't seem to be working. Thanks

[under pressure]

What should the HPOP pressure be cranking. Mine starts out at 0 and cranks for about 6-7 seconds and climbs to 400psi in 2-3 seconds and the truck seems to try to start but doesn't. It bounces between 400 and 500psi when this is happening. I let off the key it goes back to 0 in about 5 seconds. Are these pressures correct? Should it be holding pressure after I stop cranking?
As a side note: If I spray diesel in the turbo, the truck will start but stops as soon as I stop spraying in the turbo.
I have 50 psi of fuel pressure at the schrader valve when this is all happening.
Please help!!!

[STurbo90]

It sounds like you have a high pressure oil leak.

the hpop takes low pressure oil from the reservoir(rectangular tank behind coolant hose) and increases the pressure according to necessary demand. the ipr regulates the pressure, the icp tells the pcm what the high pressure is. The injectors are fired by the high pressure oil.

the pcm will not fire the injectors unless it sees 500 psi oil and 10+ volts, but it does not monitor the fuel pressure.

how are you monitoring the hpo?

you may have a stuck ipr, stuck injector solenoid, torn o-ring, or something letting the system not build pressure. If you unplug the icp, the pcm will default to a set value to try to start.

[blageurt]

I agree with STurbo , On my truck I had a dusted Top O-ring on # 6 . But all of my O-rings were in bad shape so it was only a matter of time before I had to repair them. I even replaced my IPR for nothing. International is cheaper than Ford for the O-ring kits. Also make sure you get all the oil / fuel out of the cylinders, or you will be needing a new engine.

[under pressure]

I am monitoring the HPOP pressure with a gauge in the rail. It seems to take a long time to build pressure and it loses pressure quickly once it stops cranking. Should the pressure hold when it stops cranking? I took the lines off the rails and hooked the lines together with the gauge and it built about 1000 psi and after I stopped cranking it lost pressure. It also took about 15 seconds to build that pressure?