Air in fuel or normal

[jeepmedic]

Hey group. Would like to pick some of your brains. 1998 Dynasty C8.3 mechanical. I’ve been chasing an intermittent low power issue. My boost and pedal response will just go away only to return after a few moments. Anyone had issues with the Racor fuel separator assembly on the early coaches? I think mine may be sucking air causing the issue. I’ve got a video or the fuel flow while it’s running just can’t figure how to post it.

[Ivylog]

I replaced the lift pump on my ISL because of a lose of power...did not fix. Turned out to be a small air leak where the hose attaches to the fuel tank because of a big change in temperature...the fitting was tight.

[Airstreamer6]

If those are bubbles moving when the engine is running, it appears to be an air leak that may not show a liquid leak outside of the housing because it is under vacuum and being sucked in.

[twinboat]

You should have no bubbles in the fuel system. If You do, in the lines before the pump on the engine, you have a suction leak, letting in air, somewhere.

You may not see an actual fuel leak because fuel is thicker then air and under negetive pressure until the fuel pump.

A small pocket of air can cause loss of power issues.

Check for loose connections from the filter and back to the tank.

[jeepmedic]

***UPDATE***. I was able to pull a vacuum on the fuel lines and also smoke test them. The plastic part of the bowl on my water separator unit Had a tiny hairline crack. I could get replacement parts but the unit has been discontinued and from what I understand isn’t very reliable.

I ordered part number 790R30 from the Boatstore to retrofit. I had to drill a new hole as the mounting is a tad narrower than the previous unit. Lines and control unit were a direct plug and play. Very easy swap. Power seems normal again after a 60 mile drive. Thanks for all the help. You guys are great.

[pwhittle]

Good choice on the replacement.