GM 91176135 Throttle Body Assembly(On Esn)

The carburetor or TBI unit used on earlier models is attached to the top of the intake manifold by several bolts or nuts. These fasteners can sometimes work loose from vibration and temperature changes during normal engine operation, causing a vacuum leak. If a vacuum leak is suspected at the bottom of the carburetor or throttle body, a two-foot length of fuel line hose can be used. Start the engine and place one end of the hose next to your ear while probing around the base with the other end. A hissing sound will indicate a leak, but be careful of hot or moving engine components. The air cleaner assembly should be removed, with each disconnected hose tagged with a piece of numbered tape for easier reassembly. The mounting nuts or bolts at the base of the carburetor or throttle body should be located, and any necessary special tools or adapters identified. These nuts or bolts should be tightened to the torque, but not over tightened to avoid stripping the threads.

Verify that the throttle linkage operates smoothly and inspect the throttle bore for deposits, cleaning as necessary.