Throttle Body
- Start engine. Warm engine to normal operating temperature (when cooling fan comes on). Disconnect vacuum hose (to canister) from top of throttle body. Connect a vacuum gauge to throttle body. See Fig 1 . Engine speed should be set at idle.
- Check vacuum gauge when throttle is opened slightly from idle that gauge reads vacuum. If gauge reads no vacuum, check canister port. If port is clogged, clean port with carburetor cleaner. Stop engine. Check that throttle cable operates properly without binding or sticking. Replace throttle body if there is excessive play in throttle valve shaft or if shaft is binding or sticking.