The Early Fuel Evaporation System is used on some gasoline-powered L-series engines. The system's purpose is to heat the air/fuel mixture when the engine is below normal operating temperature. The L-series engines use a system much similar to the old style exhaust manifold heat riser. The only adjustment necessary is to occasionally lubricate the counterweight. Other than that, the system should be trouble-free.
The 1980-81 and later carbureted engines use coolant water heat instead of exhaust gas heat to prewarm the fuel mixture. This system should be trouble-free.