This paper describes an IC engine fuel-system conversion to dual-fuel capability, on a carbureted Cessna 150. This conversion differs from others by adding a fuel injector in parallel to the existing carburetor. The fuel injector pump is activated when switching to ethanol. The advantage is conventional take-off and landing on either fuel with mixture full rich. Altitude leaning remains conventional. This is the first conversion to provide smooth in-flight fuel type change-over at cruise power, if the prescribed procedure is followed. This conversion method is applicable to all carbureted or fuel injected aircraft and automotive engines.