I have a 2000 dodge 2500 4x4 that is still stock. My lift pump failed after replacing the fuel filter and would not even prime the new filter. Rather than replacing with another stock pump I installed a Holley blue back by the fuel tank and the truck seems to run better. However I have noticed that with the new fuel pump, stock lift pump not in the line, when I turn the key on and the pump runs for ~1 second to pressurinze the system that I get no fuel pressure. If I bump the starter I get fuel pressure in 4-5 seconds and loose it almost immediatly after the pump stops running. I suspect that the stock lift pump had a check valve built into it to prevent drainback to the tank and hold pressure. I am going to install a check valve just before the fuel filter, but does anyone know at what pressure the VP44 bypasses surplus fuel back to the tank?

 

Check valve is not necessary. As far as I know, the stock pump did not have one, and I know I don't have one now. When starting engine, there should be 0psi to the VP44. After it starts, then you will see pressure. As for the return line pressure, I am not sure how much and how fast the VP44 is recirculating unneeded fuel. I would assume, it sends it back pretty quick, since it uses the excess fuel to cool and lub itself.

 

Think the bypass opens at 14psi plus or minus a little.
The vane supply pump in side the vp44 makes up to
or shy of 300psi. there is a check ball in the overflow
vale (bypass)