The Evinrude 9.9hp outboard is a popular marine engine for small boats. The two- or four-stroke engine -- depending on which year it was built -- causes few problems, but issues with the fuel system will be encountered on occasion. You should check four main areas when investigating fuel system problems: gas tank, fuel line, carburettor and fuel pump. Evinrude has discontinued production of its 9.9hp outboard.
- Skill level:
- Moderately Challenging
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Things you need
- Carburettor cleaner
Check the gas tank. When troubleshooting your Evinrude 9.9's fuel system, begin with the simplest part, which is the fuel tank itself. Three possible issues include water in the gas, venting problems and the fuel line connector. Boats that do not have internal fuel tanks often accumulate water in the gas tank, especially if used infrequently. Water in the gas can cause the engine to sputter and damage the carburettor. If you have not used the boat in a month or more, replace the gas. Your gas tank's vent allows gas to be siphoned into the gas line. Ensure your vent is properly opened. The fuel line connector should be cleaned or replaced if it is showing any signs of wear.
Check the fuel line. The fuel line runs from the gas tank and terminates at the engine. Possible problems with the fuel line can be the connectors, the bulb and excessive wear. Ensure the connectors are clean and properly fastened. The bulb should, after a few pumps, be firm to the grip. The entire line should be free of cracks -- gas will deteriorate a rubber fuel line over the years. If any of these issues are present, replacing the fuel line is cheaper than attempting to fix it.
Ensure the carburettor is clean and free of cracks. If the carburettor is dirty, use a carburettor cleaner. If it is cracked, you will need to replace the entire unit. If it looks healthy, pour a little gas directly into the carburettor and try to start the engine. If it starts, you may have a problem with the fuel pump.
Check the fuel pump. The fuel pump has a gasket, rings and seals which can all become cracked after years of use. If one of these three items is damaged, you may be able to find a replacement part. Otherwise, you will have to replace the entire fuel pump.
Tips and warnings
- Troubleshoot your engine while it's out of the water by using outboard "ear muffs" (flush adaptors) or a large dustbin filled with water.
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