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afp
08-21-2003, 20:52
I ordered the Mega Kit and a lift pump/fittings form JK today.

It seems to me the ideal wiring would be from an oil pressure switch. If the pump is wired directly off the ignition, then if the truck gets in a wreck and fuel line is cut, the lift pump will be pumping fuel all over the place.

The downside is wiring to an oil pressure switch means the lift pump doesn't start operating until there is oil pressure, which may cause a slow start if there is air in the line. This could be overcome by installing the Mega pre-OEM, or wiring an additional line to the lift pump relay that also provides curent on start-up. You have to be careful here, as if you wire incorrectly, you can wind up providing juice to the starter motor via the oil pressue switch which will keep the starter running after the engine starts. That happened to me once on another vehicle.

Alos, how is the lift pump at sucking fuel? It would be convienet to mount the thingunder the hood instead of by the fuel tank.

Blaine

Kennedy
08-21-2003, 21:18
Blaine,

I added a Weatherpak end to mate with the one on the pump just FYI.

I plumbed mine this evening, and still have a couple of changes to make. I haven't wired mine yet, but ran it off of a battery. Works pretty good. Holds 4 psi at idle and drops to just over 2 psi at 3200 no load. I have a VERY low fuel level in my tank too.


In time I will have some relay and oil psi switch stuff ready, but need to design and sketch it out for my electronics guy (same one that does the HB kits) so he can quote and build it...

jbplock
08-22-2003, 06:08
FWIW, here's the schematic (http://community.webshots.com/photo/77018086/78006127xwErdP) for my lift pump setup (http://community.webshots.com/album/77018086bLHHHC).

I obtained a two terminal Normaly Open OP switch from a fellow DP member

a64pilot
08-22-2003, 06:16
Possibly the reason that we get air to begin with is that we have such a long portion of fuel line under vacuum. Mounting the boost pump under the hood may not help anything as it is essentialy the same set up as stock.
I believe the best set up would be in the tank, not realistic though. Isn't the reason that the gas engines have their's there is to prevent vapour lock?