air bubbles in fuel return line
 

Lots of tiny bubbles show up in the fuel return line on my 84SD when I use clear 5/16 fuel lines and run on diesel from a bottle in the engine compartment. They show up under acceleration. There are only a steady stream of small bubbles at idle. This car has the new Bosch fuel primer of unknown age installed. There are no obvious external leaks in the lines or filters.



What are the possible leak points when the regular tank and lines are taken out of the equation?

If you search my post history, I underwent a fairly comprehensive search for bubbles in the line. Plenty of O-rings and crush washers along the way.

I need some other parts. Is there a possibility that the newer primer could be sucking air anywhere but the crush washer? The primer itself did its job when I changed fuel filters and I have no reason to suspect that it is bad.

Could be the primer handle, crush washers, the lift pump itself, plastic lines, secondary fuel filter housing, IP connections......

The Stock Filter Housing also has an air bleed hole in it which keeps some of the Air from getting into the Fuel Injection Pump and onto the Injectors.

Looks like I need several crush washers and replace the washers where ever there is a joint since there are no apparent external fuel leaks.