Checking the tightening of the TBI central injection system mounting bolt (3.1L engine) (Chevrolet Lumina 1)

1. The throttle body with the injector is attached to the top of the intake manifold with three nuts. Due to vibration and temperature changes during normal engine operation, they sometimes become loose, causing air to leak in.

2. If you suspect that there is an air leak at the bottom of the throttle body, use a rubber hose as a stethoscope. Start the engine and place one end of the hose near your ear and run the other end around the base of the throttle body. If there is a leak, you will hear a hissing sound (be careful, there are hot and moving parts on the running engine).

3. Remove the air filter (see chapter 4).

4. Install the throttle body mounting studs (see illustration).



5. Tighten the nuts securely and evenly. Do not overtighten them as the stud threads may strip.

6. If the leak persists after tightening the nuts, remove the throttle body and install a new gasket. More detailed information on this issue can be found in chapter 4.

7. After tightening the bolts, install the air filter back in place and return all hoses to their original positions.