The fuel system of a hit-and-miss engine consists of a fuel tank, fuel line, check valve and fuel mixer. The fuel tank most typically holds gasoline but many users started the engines with gasoline and then switched to a cheaper fuel, such as kerosene or diesel. The fuel line connects the fuel tank to the mixer. Along the fuel line, a check valve keeps the fuel from running back to the tank between combustion strokes. The mixer creates the correct fuel-air mixture by means of a needle valve attached to a weighted or spring-loaded piston usually in conjunction with an oil-damped dashpot.