Air in Fuel

[pausma]

I have an air in fuel problem on a common rail ISB 6.7. The engine is in a freightliner straight truck but does not appear to be any different from the Rams. There is no air between the tank and primary filter but lots of air bubbles when I hook up the pressure test guage before the secondary filter with a clear hose hooked to it and sitting in the bucket. Pressure is at 73psi which is within spec nor are there any leaks. The engine runs fine at idle and at WOT and there are no codes for low rail pressure. Any ideas where the air is getting in but performance is not affected?

I discovered the problem when running pressure checks on different fuel systems in my diesel technician class at school.

 

[sag2]

Not sure where you are getting 73 psi, because Cummins engines usually do not like pressure over about 25. And although there is no pressure specification in any diagnostic (they use volume) most trucks run less than 15 psi.

 

[DonFitzwater]

Sounds to me that you discovered a "non issue".