Engineer Owned and Operated
  • Lift Pump Relay Harness


    The 1992 - 1998 trucks run the power for the lift pump through the Oil Pressure Sensor (OPS).  The OPSs is known for failing so that the lift pump stops lifting and strains the expensive injection pump.  Also on these year trucks the lift pump only starts to prime when the engine has oil pressure (or is running).  This harness is setup in a way that it starts to prime before the engine starts and helps the engine start easier.  The third and final feature is that a small switch is located on the harness so you can prime the fuel filter with only one person.

    All of the electrical load is taken off your stock system and transferred to the harness which is built to handle it. This harness still relies on your stock electrical system to function so that all safety features of it remain. With the standard added switch you can turn on the LP from under the hood anytime you like. This is great after changing the fuel filter to purge the air out.

    This harness is also recommended for WHLP to support the lift of a more powerful pump.

    On the 99-02 Hummer they comes from the factory with Wait To Start (WTS) priming, so we don’t add it to this kit thus the price is less.

    This harness is also recommended for WHLP to better support the load of the more powerful lift pump.