[Vwdiesel] Losing Prime

[Andrew .Libby]

With the current pump I have installed on one of my vanagons, I seem to be
losing prime and requiring extra cranking to start.  I have clear line
before and after the pump and the line before the pump stays full without
any bubbles in it.  The line after the pump gradually empties, seeming to
flow back toward the pump, as the line goes up before it goes down to the
tank.  On close inspection I cannot find any leaks on the pump.  I swapped
a different pump on and the new one didn't lose prime and both lines stayed
full which leads me to conclude it is an issue with the pump itself.  I
reinstalled the first pump and it loses prime again.  I'm not sure what to
think other than perhaps the main shaft seal.  Are there any other
locations that might let air in without leaking diesel fuel out when
running?  Any other thoughts?

Andrew