If you are absolutely sure that there isn't even the tiniest leak, (my number 2 injector line was just barely seeping but it caused those symptoms), it might be the return line check valve.

On the VP44, there are two banjos on the left side. The bolt that holds the rear one on the vp, is the check valve.

It's not a common failure item but it can leak. You can check it with compressed air. It should open at around 14 psi. If it leaks, it will allow fuel to bleed back to the tank, draining the vp.

 

your crossover tube orings are leaking thats exactly what happend to mine. when i parked the nose down hill it would start and if it was parked up hill it allowed the fuel to run out so it would crank and crank and when it started it would puff white smoke on account of too much air and not enugh fuel... i bet if you put new orings in there she will start fine

 

I had a similar problem, and it turned out to be the return fuel hose.

 

can anyone explain why the fuel return hose would cause this?

 

I have been down this road and turned out 2 injectors were bad, took them and had them tested to find this out. May be worth looking into. Went thru new IP and LP before finally figured out injectors