Fuel injection is the process by which the engine 'injects' fuel directly into the combustion chamber. Fuel injectors 'atomize' the fuel more efficiently, which causes the fuel to burn better, thus giving your Buick V6 enhanced performance and better fuel mileage. It also helps maintain your internal engine parts by keeping them cleaner. Most fuel injectors are sealed with O-rings. Over time, the injectors and O-rings can deteriorate. Replacing a fuel injector in your V6 Buick is a challenging task, but one that a novice mechanic can accomplish in less than two hours using the correct tools.
Bring your Buick to a complete stop. Disengage the engine and open the hood. Allow engine to cool. Remove the negative battery cable by loosening the cable clamp with a wrench. Move the cable to the side.
Look at the top of the engine fuel manifold cover and see a round port with the fuel pressure valve in it. It resembles the valve stem you would find on your tires. Attach a fuel pressure gauge. The pressure gauge is equipped with a release valve and an overfill hose. Put the hose into a fuel container and open the release valve to let the fuel out. Close the valve and detach the gauge.
Remove any covers that may be blocking access to the top of the engine. Remove the fasteners with a ratchet and socket.
Loosen the clamps of the air intake pipe on the throttle body. Use a screw to loosen the clamp and pull the hose off.
Disconnect the cables for the cruise control (if equipped) and throttle cable. Use a small pry tool to pop the cables off. Then follow the cables back to the brackets holding them to the upper intake manifold. Remove the bolts retaining the brackets with a ratchet and socket.
Inspect the upper intake manifold and take a note of any hose or electrical cable attached to it. Use some tape and a marker to tag them for identification. Detach the items. Electrical connectors need to be squeezed and pulled to be removed.
Remove the bolts retaining the EGR valve and the MAP sensor valve with a wrench. Pull both valves from the engine.
Tag and number the spark plug wires and then pull them from the spark plugs by pulling on them with your fingers.
Remove the mounting bolts of the upper intake manifold with a ratchet and socket. Pull the manifold from the engine and set it on a workbench. Throw any gaskets into the trash. Stuff shop rags into any opening exposed by the removal of the manifold
Separate the fuel lines attached to the fuel rail manifolds. Use a wrench to loosen the fittings. Wipe up any fuel that may spill. Throw away the o-rings. Tag, label, and disconnect any electrical cables from the fuel rail.
Remove the vacuum hose attached to the fuel pressure regulator. Then remove the retainer bolt with a wrench and remove the regulator.
Loosen and remove the mounting bolts of the fuel rail with a ratchet and socket. Use your hands to pull up on the fuel rail. The rail will come up and the injectors will come out with it. Pull the retainer clip and the injector will come off of the rail. Throw away all o-rings.
Clean the entire area, especially the mating surfaces of the upper intake manifold. Remove all gasket material.
Lubricate the new injector o-rings with some new engine oil and slip them onto the new injectors. Put the new injectors into the fuel rail and slide the clip on.
Push the fuel rail and injector assembly down into the lower intake manifold. Install the mounting bolts and torque them to 84 inch-pounds with a torque wrench.
Attach new o-rings to the rail fuel lines and reconnect them. Tighten the fittings to 13 foot-pounds with a torque wrench.
Position the new upper manifold gasket and lower the manifold down over. Install the mounting bolts and torque them to 19 foot-pounds with a torque wrench. Work your way out from the center when tightening.
Reattach the spark plug wires according to the labeling you did previously. Push the spark plugs on until they seat.
Remount the EGR and MAP sensor valves and tighten the bolts with a wrench. Reconnect any vacuum hoses or electrical connectors you labeled in step 6. Make sure everything is secure.
Reattach the throttle cable and cruise control cable to the throttle body by pushing them on. Reattach the cable mount brackets and bolts with a wrench.
Slide the air intake tube back onto the throttle body and tighten the clamp with a screwdriver. Reinstall any engine covers you may have removed and tighten the bolts with a ratchet and socket.
Reconnect the negative battery cable to the battery and tighten the clamp with a wrench. Engage the engine and check for any leaks.
