Troubleshooting a generator that fails to start often reveals a fuel problem. While mechanical issues can also prevent starting, they are far less common. If the engine starts and idles at the correct speed but the unit does not provide adequate power, the problem may be with the generator system. When diagnosing fuel problems, begin by checking the fuel tank and ensuring it is full of fresh fuel.
With gasoline engines, fuel problems often directly relate to the carburetor. A faulty carburetor adjustment can prevent the engine from starting, idling, accelerating or operating correctly at its working speed. In these cases, adjusting the idle screw may fix the problem. After several hundred hours of operation, the carburetor becomes dirty and requires cleaning or rebuilding. Problems with gaskets and plugs can cause leaks from the carburetor.
If the generator is diesel-fueled, it can also experience fuel problems. If the temperatures are very cold, the fuel becomes so thick that it plugs the fuel line. In altitudes above 3,000 feet, the air density is too low for the proper fuel-to-air ratio. Use of fuels other than automotive diesel in the unit may prevent it from working due to the wrong flash point for the fuel.