Hey guys my o3-o4- 6liter 4x4 goes into limp mode i think thats what its doing any how u can rev it up to 2500rpm or probably higher in park but seen no need to go any higher but then u put it in ti gear drive or reverse dont matter and it basically dies theres nothing there i have a in floor hoist in my shop that sits 2 in. above the concrete and it doesent have the power to back over it,i switched out the ficm,the pcm, and the little unit on pasengers side valve cover cant recall the name right now,checked every fuse and changed all relays with working ones a boutr a hundred times thinking i may have missed one,i changed fuel filters twice and the lift pump once i put a in line manual fuel pressure gauge i got 55lbs and after weeks of this all i got is a head ache,LOL please i need help,i also cleaned the fuel tank and put in new fuel,all my parts were not new from a wrecker,

 

Have you replaced the ICP sensor on the HPOP, when they go bad they can make the truck act like this, oil seaping through them makes them fail and give false readings.

 

Going to need more info about the truck.

Throwing parts at a truck is never a good fix, and this is where 6.0's get a bad rep.

Diagnose, verify, repair. We need to diagnose first.

When did this start? Out of the blue? Slow and painfully? Any smoke coming from the truck? How does it start? How many miles on it? Read the sticky at the top of the page for new guys asking tech questions first.

Good news is, we can help. We just need more info. Welcome to DB!