Lift Pump Pressure

[Basshopper]

I know that the oem lift pump is 4-7psi. Does anyone know the max psi a electronic IP can take from a lift pump without damage to it?

[tom.mcinerney]

There have been a couple relevant posts....
I think the (outwardly identical) LP for the mechanical 6.5Ls had output of 4-14psi. This was internally regulated in a mod for electronic service.

[JohnC]

The injection pump has it's own internal pressure regulator. Any pressure beyond its setting will be dumped back to the tank, so there's really no point. What you need is volume.

[jspringator]

I am showing less than 1 psi on my heath guage post lift pump, pre injection pump at WOT. My lift pump is fairly new (<2 years) and has been protected by a filter. I suspect my prefilter has reduced my fuel pressure. Changed filter; no effect. I would like a higher pressure pump.

[BobND]

You either a have a restriction... damaged line, plugged "sock" or filter, or a bad fuel pump.

Even the OEM fuel pump, in working order, certainly should do better than what you are seeing.

[rjwest]

James Springate: as I read your post I
understand that there is an additional filter in series with the OEM filter.

I also have a primary filter before the lift pump.
IE: Fuel from tank to filter, lift pump, OEM filter, IP.
( I do get water out of the primary filter, never got any water out of the OEM filter before and after the Modification. )

My fuel pressure also drops to 1 psi ,even lower at some high power hill climbs ( 0 PSI ), also I have noticed on some " cyclic bumps " the pressure would fluctuate to zero..

I have never flelt the eng losing power but I decided to install a 2nd lift pump in series between the tank and the primary filter, when
pressure drops I switch on the 2nd pump...

My fuel pressue will run at 9 psi at idle and about 5-6 in cruise with a 3k load, single pump operation, with both pumps running,pressure back up to 6-10 psi,
Also, real easu to bleed system after filter changes, turn on 2nd lift pump, bleed, turn off pump..

Note: Lift Pump is design to allow fuel to be sucked through it if it is not operating....

[JohnC]

I think what you're seeing is pretty typical. As long as there is a positive pressure the injection pump has more fuel that it needs. there is an internal pump in the injection pump that sets the pump's internal pressure and if it's being fed under pressure rather than having to draw fuel all is well.