so our 2004 6.0l started having running issues last week, it started on the way home one day where it lost power. now it has very long cranks if it will even start cold or hot. if it does start it has zero throttle response it will not rev at all. we tested the ficm and it was ok with the ignition on at 47v when we were cranking it varried from 46-42v and same with running. we also tested the hpop pressure and it was 175psi one time and around 200 the next. so my question is would the hpop being out of spec cause no throttle or would it be the ficm because according to all i have read they are both way low under running spec. this truck is stock no performance mods at all. and it makes no difference if the motor is hot or cold.

 

Sounds like the HPOP is on it's way out. The truck is supposed to have 525psi of high pressure oil to even fire. Full throttle it should be up near 4000psi. How were you testing it? A gauge, or with a scanner? You need to monitor ICP actual and ICP desired. Desired is what the PCM wants, and actual is what the high pressure oil pump is really putting out. They're supposed to be really close to each other at all times. You can also pull the IPR valve and inspect that, if there is metal shavings on the screen, it's HPOP time. How many miles on this truck?

 

We have a guage that we put in place of the icp valve to test the pressures. It did end up being the hpop, the truck has somewhere around 180k.

 

Those FICM numbers are not OK.

I would have it repaired before it quits working.

 

HAD THE SAME SYMPTOMS IT ENDED UP BEING MY HPOP