Push starting, also known as bump starting, roll starting, clutch starting, popping the clutch or crash starting, is a method of starting a motor vehicle with an internal combustion engine that has a manual transmission, a mechanical fuel pump, and a mechanically driven generator or alternator. By pushing or letting the vehicle roll downhill then engaging the clutch at the appropriate speed the engine will turn over and start. The technique is most commonly employed when other starting methods (automobile self starter, kick start, jump start etc.) are unavailable. The most common way to push start a vehicle is to put the manual transmission in second gear, switching the ignition to on/run, depressing the clutch, and pushing the vehicle until it is at a speed of or more, then quickly engaging the clutch to make the engine rotate and start while keeping the gas pedal partially depressed, then quickly disengaging the clutch so it does not stall. Types Push starting is most successful when the automobile is using a gasoline engine, uses a carburetor, and uses a capacitor discharge ignition (CDI) or an inductive discharge ignition system. Automobiles with other types of engine, ignition, and fuel delivery configurations may work, but may be more difficult to start. Some engines must have a battery providing some electricity since fuel injection systems must have power to operate. Automatic or manual gearbox A vehicle equipped with an automatic transmission (including semi-automatic (clutchless manual) transmissions) is difficult to push start since selection of transmission gears is possible only when the internals of such a gearbox are rotating. However, automatics with both front and rear hydraulic pumps can be push-started with no problems. The last American automobile with this type of transmission was the 1969 Chevrolet Corvair with a Powerglide automatic. While push-start can cause more damage to a hydrolocked engine, the starter motor is limited. Petrol or diesel engines A diesel engine uses heat and high compression (compression ratios commonly 22:1 versus 9:1 for gasoline) to ignite the fuel. When normally starting a modern diesel engine, it typically uses glowplugs to preheat the cylinder(s). If a battery is completely discharged then it may not provide the necessary power to heat the glowplugs, making the push starting of a diesel vehicle with a depleted battery almost impossible. Fuel delivery systems Fuel injection is most common for modern gasoline and diesel engines. Fuel injection needs electrical