Ok.. 2007.5 6.7 cummins 6 speed manual.. deletes smarty sr. straight pipe.. fass fuel.. while trying to drive down the road it willjust intermentinly defuel.. for ladck of a better definition... its like you floor it then completely let off gas pedal and it does that like every 4 seconds... fuels for say 7 seconds then falls on its face for like 4 seconds... all my guages stay the same so i don't think its electrical... put new fuel filters fuse and relay on fass so i dont think thats it..i really need help... if ya'll have to have codes i will get them but if you have any ideas please help me.. it has 300,000 miles...

 

Could be CP3 or Injectors

Luke

 

EEWWWW.. don't say that... what would be the reason for popping fass relays???

 

sounds like something wrong with your fass pump. you might call fass and tell them about relay problems

 

pulled a low rail pressure code and an intermittent pcm/ecm supply voltage low code.. any more ideas?? could the fass have a hole between tank and pump causing it to suck air and overwork itself?? or should i be looking towards my charging and electrical system?? acts like fuel problem to me but what do i know

 

TTT

 

The supply volts low would have me lookin at the electrical, if the volts to the pump are low the electrical issue could be causing a fuel issue.

 

Well i have fixed the problem and i don't think ya'll will ever guess the cause of this!!! tire man your are right but WHICH electrical part..

 

Ok guys this actually did not fix this problem... i've traced this problem back to my fass.. i think.. it will hold 18 pounds until you rev it then it will drop to 0 and not rebuild but will still run..