Re: warm engine starts very bad

Posted by TxGoat On 2023/6/25 14:26:29

If the starter cranks the engine as it should when hot, most hot starting issues are related to flooding.

The carburetor may leak fuel into the intake, flooding the engine, then not have any fuel in the bowl once the flooding condition is eliminated.

The electric fuel pump should eliminate any vapor lock issues, but vapor lock in hot weather is often a problem. In some instances, an electric fuel pump can have too much pressure for the application and contribute to flooding.

The carburetor may have internal leaks, a high float level, or it may be boiling over to to excess heat under the hood and the low boiling point of most modern-day gasoline.

The 120 has a thermostatic intake manifold heat valve, and if the valve is sticking shut, which they often do, it will cause carburetor boilover, usually after a brief stop in warm weather.

The 120 also has an unusual, small drain pipe on the intake manifold, which is designed to reduce flooding. It has a check valve at the lower end, and if the check valve is stuck or plugged up, it will increase the tendency of the engine to flood.

A shop manual is a good thing to have. Reprints are available and the various manuals can be found in the Literature Archive on theis website.