Signs of Bad Gasoline or Fuel Filter in an Outboard

Signs of Bad Gasoline or Fuel Filter in an Outboard

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Your outboard motor is the heart of your marine vessel and if it is having trouble with the fuel supply, it can put a damper on your day on the lake, river or ocean. Two of the most common problems when it comes to fuel supply in your outboard motor are bad fuel and a bad fuel filter. If you have one or both of these problems, then you need to remedy the situation before you can enjoy your outing. Knowing how to recognize, prevent and deal with the problems will make you a more efficient boat owner.

What "Bad Gas" Means

Getting "bad gasoline" in your outboard can mean two different things. You may have put gas into the fuel tank that is tainted, or it may actually go bad inside the motor. When trash or water gets into the fuel supply, it can clog the system or at least cause it to run improperly. If the fuel sits in the tank too long without use, the gas can go bad as it loses octane, begins to separate from the fuel additives or it begins to gum up the fuel system.

Signs of Fuel Problems

Knowing if you have a fuel problem is fairly simple even to those who are not mechanically inclined. Sure signs that there is a fuel or fuel filter problem include a loss of pressure in the fuel pump that leads to loss of power or the inability to start the engine. The motor may surge at high speeds or it may cut out or hesitate. Occasionally, the motor will quit altogether and will not re-start.

Causes of Filter Problems

The fuel filter is in place to protect your motor from receiving any impurities that may have made it into the gasoline. But like any other type of filter, it will eventually clog up with the materials it is filtering out. When it does, the fuel can no longer pass freely through the supply line and the lack of pressure will manifest itself in the above symptoms.


Preventing fuel problems in your outboard can be as simple as using fuel stabilizer in fuel that has been sitting unused for more than three months. In fact, adding stabilizer to the fuel tank and running the motor for a few moments to circulate it can help before winter storage. Keeping your fuel filter in good condition is also an important preventative measure. You should ideally replace the fuel filter at least every year for best performance. It is located under the motor's main cover.

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