GM S10/S15/Sonoma Pick-Ups 1982-1993 Repair Manual

Fuel Pressure Relief


Prior to servicing any component of the fuel injection system, the fuel pressure must be relieved. If fuel pressure is not relieved, serious injury could result.

A valve is provided on these fuel systems in order to conveniently test or release the fuel system pressure. A fuel pressure gauge and adapter will be necessary to connect to the fitting. The 4.3L MFI system uses a valve located on the fuel rail assembly, immediately before the pressure regulator in the fuel circuit.

  1. Disconnect the negative battery cable to assure the prevention of fuel spillage if the ignition switch is accidentally turned ON while a fitting is still disconnected.
  3. Loosen the fuel filter cap to release the fuel tank pressure.
  5. Make sure the release valve on the fuel gauge is closed, then connect the fuel gauge to the pressure fitting located on the fuel rail.

When connecting the gauge to the fitting, be sure to wrap a rag around the fitting to avoid spillage. After repairs, place the rag in an approved container.

  1. Install the bleed hose portion of the fuel gauge assembly into an approved container, then open the gauge release valve and bleed the fuel pressure from the system.
  3. When the gauge is removed, be sure to open the bleed valve and drain all fuel from the gauge assembly.