Fuel lift pump wiring diagram

[Lug]

Evening. Does anyone have a scanned copy of the wiring diagram for the fuel lift pump on a 1995 K2500? My "new" pickup has an undocumented fuel pump relay mod installed. It appears that the 10A IGN-E fuse socket pins have heen removed. A pigbacked fuse adapter is plugged into the 20A FUEL SOL socket. This piggyback is feeding a generic relay on the firewall. And then they cut the hot wire on the pump and spliced the new hot lead in. I will try to post pictures for entertainment purposes.
Justin.

[Robyn]

Whoever did this has wired the fuel transfer pump to operate anytime the ignition is turned on.....

Originally the ECM operates the fuel pump for a short period of time to make sure the fuel pressure to the injection pump is up to spec ....This will happen during the glow cycle on a cold start.

After the engine is started the oil pressure switch (Two sets of contacts in these....one runs the gauge...the other set sends power to the transfer pump)

Also on the 1995 trucks (OBD1) THE TRANNY CAN BE PLACED IN DRIVE and then turning the key to start will activate the transfer pump without operating the starter.

I am suspect that possibly the Oil pressure switch died (Common) and the other folks decided to wire around things to get the transfer pump going.

Although the way they did it works....The fail safe fuel pump shut off is not operational and in the event of a wreck the fuel could continue to flow even if the engine had died.......


I do not have the schematic for the 95 .....But my bet is that the oil pressure switch is toast.

Why the Fuse E pins would have been removed ?????????????????? anybodies guess....

[More Power]

The best way to wire in a separate relay to power the lift pump is to use the oil pressure switch to activate the relay. Kennedydiesel.com once offered a kit to accomplish this. If done well, an owner mod to do this can make the lift pump operation more reliable. You can also wire in a separate push-button to activate the lift pump relay - to make priming a new fuel filter much easier.

[Lug]

An update. Took the fuse box apart and there is no wiring for the IGN-E fuse position. But I did find a couple of images supposedly for a 1995 6.5 and the fuel lift pump gets power from ECM-B fuse. Replaced OPS. Wired in another pump relay the same way as I did my 94 Suburban. Miserable new ChiCom Carter lift pump failed in less than a minute of use, 14 megaohms of resistance. Guess I am buying an upgraded pump and filter setup earlier than planned. Also looks like a new ignition switch is in order. Havd a failed pmd no start condition, and have tried 2 different drivers, 2 different extension harnesses. Even plugged a driver into the stock harness and still no joy. I hate misbehaving electrons.
Justin