Rick 12v CTD

Title.

Just wondering at what pressure the injector pump return actually starts to return fuel to the tank.

Like on a second gen truck it's typically between about 25-35psi.

JD730

All the time, there is no spring in the overflow valve on a VE pump, there's a small hole that is sized for the particular application, case pressure is over 100 psi and increases with rpm, that's how the variable timing of the pump works.

dzl_damon

you could put a pressure gauge on the case and see what it is. I think it gets to over 200psi internally? A lot of the high horsepower guys know because they will manipulate it.

Rick 12v CTD

ahh gotcha. good to hear, and that makes sense. I was kinda thinking that it wouldn't make sense that it would return the same way as a ppump. I wonder what kind of pressure it would go to if it didn't have a return... or if you were able to push enough fuel to actually make it drop a lot to have a shut off thing on there if the pressure dropped below a certain PSI.

TRENDZ

I'm a little confused. I was under the understanding that case pressure shouldn't exceed 20 psi without making the input shaft seal positively retained with a snap ring.

dieselJon

Trendz, case pressure and inlet pressure are 2 different things.

The vane pump is separated from the main body. So inlet pressure puts direct pressure on the seal.

TRENDZ

Ahh... That clears up a few questions for me. Thanks!