The Chevrolet S-10 Blazer was a mid-size SUV manufactured from 1983 to 2005, with the last major redesign occurring in 1995. The 2004 Blazer had a 6-cylinder 4.3L engine with multi-port fuel injection requiring a high-pressure electric fuel pump. The procedure for replacing the fuel pump is the same in all versions of this vehicle. The fuel pump is part of the fuel-sending unit on the fuel tank, so you must remove the fuel tank in order to replace the fuel pump.
Disconnect the cable to the negative terminal of the battery with a socket wrench. Install Fuel Pressure Gauge J 34730-1A to the fuel pressure connection on the fuel rail. Loosen the fill cap for the fuel tank, and open the valve on the fuel pressure gauge. Disconnect the fuel pressure gauge from the fuel pressure connection.
Drain the fuel tank and support it with jack stands. Remove the filler neck for the fuel tank. Disconnect the fuel tank shield and the retaining straps for the fuel tank. Detach the fuel lines and electrical connector from the fuel pump. Disconnect the fasteners for the fuel tank with a socket wrench and lower the fuel tank from the vehicle with the jack stands.
Turn the locking ring on the fuel tank counter-clockwise with a spanner wrench. Remove the locking ring and detach the fuel pump from the fuel-sending unit. Discard the O-ring that is on the fuel tank.
Install the new O-ring on the fuel tank and lower the fuel-sending unit into the fuel tank. Avoid damaging the fuel strainer as this can restrict fuel flow. Turn the locking ring clockwise with a spanner wrench. The cam-locking ring will lock into position under the locking tabs.
Connect the fuel tank to the vehicle and tighten the fasteners to 33 ft. lbs. with a torque wrench. Attach the fuel lines and electrical connector for the fuel pump. Fasten the restraining straps and shield for the fuel tank. Connect the filler neck for the fuel tank. Connect the cable to the battery's negative terminal. Start the engine check for fuel leaks.
