For GM / General Motors. Lift pump diagnostics and driveability diagnostic require the ability to measure high fuel pressure at the service port on the front of the engine. EN-47620 allows the service port on the engine (the same one that is currently used to measure vacuum in the fuel supply system when the engine is running) to be accessed with previously Essential J-34730-1A Fuel Pressure Gauge to test for high pressure in the fuel supply system.
