Repair 7

Raise the front of your Trailblazer with a jack and support it on a set of jack stands positioned under the frame rails. Slide under the passengers side of the vehicle and locate the catalytic converter in the exhaust pipe between the engine and the muffler.

Locate the oxygen sensor in the converter. Follow the wire from the sensor to the wire harness connector and disconnect it from the harness. Place an oxygen-sensor socket on the sensor and remove it from the converter with a ratchet. Set it aside.

Loosen the two bolts on the mounting flange between the rear of the catalytic converter and the exhaust pipe using a socket and ratchet. Remove the bolts from the flange and pull the pipe aaway from the converter. Push the pipe aside.

Move to the front of the converter and remove the two mounting bolts between the flange and the front pipe with a wrench. Pull the converter out and remove it from under the truck.

Position a new converter in place under the truck. Lift the converter up into place and install the retaining bolts from the front pipe to the front flange on the converter. Leave them loose for now.

Position the rear pipe up against the rear flange and install the rear mounting bolts loosely. Tighten the front bolts by torquing them to 33 ft.-lbs., then tighten the rear bolts to 33 ft.-lbs. as well.

Install the oxygen sensor from the old converter into the new converter and tighten it with a oxygen sensor socket and ratchet. Connect the wiring harness connector from the oxygen sensor to the wiring harness connector on the truck. Push the connectors together until they lock in place.

Raise the front of the truck off the jack stands with a jack. Remove the stands from under the truck, lower the jack and remove it from under the truck.

Remove the cable from the negative battery terminal. Open the filler cap on the fuel tank to release the pressure in the fuel tank.

Connect a fuel pressure gauge to the pressure fitting on the inlet fuel line. Place the bleed hose of the fuel gauge into a container approved for gasoline. Open the valve on the pressure gauge to relieve the pressure in the fuel system. Drain the fuel from the pressure gauge into the container, then disconnect the pressure gauge from the pressure fitting.

Disconnect the outlet resonator for the air cleaner with a socket wrench. Release the retaining clips for the main wiring harness on the front of the engine, then detach the wiring harness.

Remove the vacuum line from the fuel control regulator. Clean the surrounding area with a shop rag. Release the retainer on the fuel return line for the fuel control regulator, then detach the fuel return line. Release the retainer for the fuel control regulator with a socket wrench. Detach the regulator from the fuel rail. Discard the O-ring on the fuel control regulator.

Install a new O-ring to the new fuel control regulator, and coat the O-ring with engine oil. Push the new fuel pressure regulator into its housing on the fuel rail. Attach the retainer for the fuel control regulator, and tighten it to 71 inch-pounds with a torque wrench.

Attach the retainer for the fuel return line to the fuel control regulator. Tighten its retainer screw to 71 inch-pounds with a socket wrench. Connect the fuel return line for the fuel control regulator.

Fasten the filler cap on the fuel tank, and connect the cable for the negative battery terminal with a socket wrench. Turn the ignition on for two seconds to prime the fuel system, then turn it off for 10 seconds. Turn the ignition back on and check for fuel leaks. Connect the engine wiring on the front of the engine, and attach its retaining clips. Install the resonator for the air intake.