Do I have a injection pump Problem

I am trying to prime my injection pumpand have a question.


Have mighty vac hooked to return line out of injection pump.


Have inlet line submerged in a can of fuel so I know its not sucking air.


When i pull a vacumm I will get a lot of air at first,then if I let it sit after the large bubbles are drawn out and line is full of fuel it will hold a vaccum
but I will get some air out of the return.


Should the IP hold a vaccum and if so how long.

Don_and_Herbie said:

I am trying to prime my injection pumpand have a question.


Have mighty vac hooked to return line out of injection pump.


Have inlet line submerged in a can of fuel so I know its not sucking air.


When i pull a vacumm I will get a lot of air at first,then if I let it sit after the large bubbles are drawn out and line is full of fuel it will hold a vaccum
but I will get some air out of the return.


Should the IP hold a vaccum and if so how long.

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It will keep some vacuum for as long as the fuel flows to the miteyvac pump. As the fuel flows towards the hand pump, the vacuum naturally drops slowly.

It sounds like your pump is primed correctly if it's mostly fuel. There are air bubbles trapped in the pump so it isn't surprising that some still get released during initial priming.

It is more effective to prime the VP 37 system with pressure than vacuum. I say this because the design of the hydraulics inside the hydraulic head (the high pressure pumping element) is such that if any injection lines are loose, air will enter back into the pump through that line when vacuum is applied. This design is one of the differences between a VP and the older VE pumps. I wrote the below a few years ago on how to COMPLETELY prime the VP 37 system all the way to the injectors.

http://forums.tdiclub.com/showthread.php?t=438031