AHU air leak from pump?

[hotpod]

hi chaps, i have stuck an AHU tdi in my camper and have it running but cant maintain fuel pressure in the lines. i have now changed the filter and thermo valve and stuck a non return valve and a priming bulb pump on the flow line. i can pump it all up and push all the bubbles out of the (clear) return line and it stays good for about 15 seconds then something gives and i get a rush of air bubbles from the pump end into the return line.
the van will only run for a few secnds after priming it unless i keep squeezing the bulb.
any ideas?

[Evsi]

Sounds like internal pump failure, although, have you checked the banjo bolt washers and anything serviceable?

[scimdiesel]

I had a simularvproblem with my old aaz. First Check all the unions are good and no cracks if the metal inlet if has been bent this can crack it at the braze. There should be copper or aluminum sealing washers on the unions. Another sorce of air in the system is the leak off pipes between injectors. Since the pump has no levers there is no leakage path there at least.

My aaz would run for a while then stop. With some tempary clear lines I could see it was drawing in clean air free diesel and pumping out pure foam. Air had to be getting in! I put one of those Granade pumps on the return line to suck fuel through the pump. When doing that I could hear air being drawn into the pump. After some time listening I found it was the main shaft seal.. I changed that and it was perfect after.

[hotpod]

cool.
i shall get checking all the unions and perhaps try some other inlet pipes.

[hotpod]

seems to be much better now without any more tinkering.
could it have just needed a really good bleeding or something? air lock?
it still wont rev much but currently there are 101 other possible reasons for that so not too worried just yet.