THERMO-Time Switch & Hot Start Relay

The thermo-time switch controls opening time of cold start valve. It is affected by engine temperature and starter current. Depending on coolant temperature (or engine temperature on air-cooled engines), the switch will take from 3-10 seconds to open. Injection through the cold start valve will then stop.

Some models use a hot start pulse relay to improve hot starting. While the starter is being operated, the relay allows the cold start valve to spray small amounts of fuel at regular intervals, until the engine is started.