Well I have a bit of a problem, not sure how or where this air is getting in there. I have an 1983 300-SD converted with the dual tank system from greasecar. On both fuels, I am getting air bubbles you can see in the inlet pre-filter for the lift pump, although it's worse on WVO. the bleeder pump is the original screw type if that matters. All the lines are tight, and when I by-pass the solenoids, I still get the air being pulled into the pump. Once enough air has entered the pump it starts to idle very poorly, has no power and will eventually stall. Only way to get it going after this to go out and bleed the air out by pumping the plunger.

You're seeing air in the filter between the hand pump and injector pump?

Probably need to replace the hand pump. They will start to leak and draw air in.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

no, I am seeing air in the clear pre-filter. that is, air bubbles and foam I can see in the clear filter looks to be getting drawn into the hand pump which in turn goes into the injector pump. the order of the components is a bit re-directed in the grease car kit.

First things first, you need to upgrade the plunger pump to latest version. As a general rule of thumb, everyone with the old-style plunger pumps should upgrade in order to eliminate a common source of leakage. It's $20 well spent for peace of mind.

I ordered one yesterday from ************** to eliminate some of the potential air leaks, I could have bought just the hand pump for $19 but I also bought the entire lift pump that came with it. entire thing brand new was only $120, so I figured why not? however being that this unit is located AFTER the pre-filter (where I am seeing the air bubbles entering) I do NOT think this is the primary source of my air leaks, but I have little doubt that it at at least a contributor to the problem...

anyone have any other ideas?

Well start with what you know. If your seeing air going into the primary filter, then your leak is in front of it.

Check every connection on the fuel line before it splits off.

__________________
'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.