The fuel pressure Schrader tap is being removed from the 3/8" fuel supply line on vehicles with the 2015 Gen 4 engine. GM-37287-1A installs into the fuel line at the quick-connect fittings. GM-37287-1A has two Schrader fitting taps on each side of a shut-off gate valve. The male and female ends on the adapter connect to the vehicle fittings. The GM-48027 Digital Pressure Gauge connects to the Schrader tap so the supply fuel pressure can be determined and compared to eSI specifications. The dual taps and gate shut-off valve allow additional diagnostics to be performed such as injector leakdown check, pump regulator leakback check and fuel pressure sensor correlation.