This switch powers the fuel lift pump after the engine is started and all the while it is running. This new switch is the heavy duty GM replacement for the original factory unit.
You can do a basic check of this switch by openning the fuel filter drain cock while the engine is idling. If the oil pressure switch is operating and powering the lift pump, fuel will flow out of the drain cock hose. If no fuel comes out and if the engine dies, that would indicate that the pump is not running and the likely culprit is a failed oil pressure switch.
Brand: HDP PerformanceHDP Part Number: #HDP1484
