GM 6.5, it is inline not in tank.
you use the diesel sending unit without a in-tank pump, or a modified gasser sending unit with the low pressure pump removed.. and then you install the GM lift pump under the car where the water separator/high pressure pump used to be..
Not sure if I'm over thinking this, but are you guys simply running them off anything that's showing 12v, including when cranking?
My only thought would be to wire the lift pump on a separate, custom circuit that was only live when the engine is running. Kinda like how a gasser fuel pump needs a coil signal.
-Todd
I run a separate wire off of the 12v that the fuel seliniod gets. That way when the key is on the pump is on. I have it with an insulated pull apart terminal so if I wanted to run the stereo for 5 hours I can pop the hood and pull it off. I also have it fused, so I could pull the fuse as well.
What's the purpose of the lift pump if your IP is good? I thought you'd only want to use one if your pump isn't priming properly.
-Todd
if you want power, then vacuum at the pump inlet is bad.. it makes the timing advance later than if the pump had pressurized fuel waiting for the vane pump to inhale..
basically, is it easier to suck fuel thru a 20ft drinking straw, and fuel filter? or is it easier to let the fuel simply flow out of the 20ft drinking straw, and be delivered to the pump, rather than be pulled to the pump..
you can STARVE the pump of fuel in the higher rpms, and with a lift pump, it doesnt happen. when the engine is revved up, the vane pump is making LOTS OF VACUUM, and it can aerate the fuel in the lines from vacuum. if you have a lift pump, and any amount of positive pressure, the fuel will NOT AERATE..
Sorry to bump this up again, especially on my first post!
But does having positive pressure at the lift pump not affect internal pump pressure and hence advance rates? Reason I ask is I'm running a 1.9XUDT 306 on WVO and something to get the fuel to the pump easier would be a great advantage!
What's the purpose of the lift pump if your IP is good? I thought you'd only want to use one if your pump isn't priming properly.
-Todd
if you want power, then vacuum at the pump inlet is bad.. it makes the timing advance later than if the pump had pressurized fuel waiting for the vane pump to inhale..
basically, is it easier to suck fuel thru a 20ft drinking straw, and fuel filter? or is it easier to let the fuel simply flow out of the 20ft drinking straw, and be delivered to the pump, rather than be pulled to the pump..
you can STARVE the pump of fuel in the higher rpms, and with a lift pump, it doesnt happen. when the engine is revved up, the vane pump is making LOTS OF VACUUM, and it can aerate the fuel in the lines from vacuum. if you have a lift pump, and any amount of positive pressure, the fuel will NOT AERATE..
Sorry to bump this up again, especially on my first post!
But does having positive pressure at the lift pump not affect internal pump pressure and hence advance rates? Reason I ask is I'm running a 1.9XUDT 306 on WVO and something to get the fuel to the pump easier would be a great advantage!
you can feed the pump with 150psi to the INLET and not change the advance curve..