Quicksilver Blog

How to Change a MerCruiser Fuel Filter

The fuel filter on a Mercury® MerCruiser® sterndrive or inboard gasoline engine should be changed annually, or after every 100 hours of operation. For many boat owners, changing the fuel filter is part of an annual service performed before winter or offseason lay-up, along with an engine oil-and-filter change and fuel treatment. It’s important to change the fuel filter because any water trapped in the filter could corrode the filter canister over the offseason, and you’ll want to start the next boating season with a fresh filter.

Installing a new Quicksilver® fuel filter is not a challenging task for the do-it-yourself boat owner. This video hosted by Scott Glorvigen of Wired2Fish demonstrates the process of changing a fuel filter in a MerCruiser 4.3L V6 engine. The procedure will be similar for other MerCruiser engines. Your MerCruiser engine owner’s manual will outline the steps for your particular engine model. Note that the location of the filter may be different than that shown in this video. If you don’t have an owner’s manual or service manual, a copy may be downloaded or ordered directly from MercuryMarine.com or from a Mercury Authorized Dealer.

Essential Tools

Changing the MerCruiser fuel filter requires an adjustable filter wrench, rags or paper towels, a catch pan and a container for the fuel drained from the filter. A premium Quicksilver water-separating fuel filter offers OEM-quality fit and performance and is available for MerCruiser sterndrive and inboard engines, many Volvo Penta® sterndrive engines and many other gasoline inboard engines.

Pro Tip: Before installing the new fuel filter canaster, lubricate the rubber gasket with a small amount of engine oil, applied with a rag or your fingertip. This will prevent the gasket from being displaced or damaged when the filter is tightened on the engine.

Fuel Treatment

Before putting the boat up for long-term or offseason storage, it’s important to treat the fuel with a quality product such as Quicksilver Quickstor® fuel stabilizer. Quickstor stabilizes fuel for up to a year and keeps fuel ready to use when it’s time to put the boat back on the water.

Benefits of Quickstor include:

  • Prevents regular and ethanol-blended fuel from breaking down and oxidizing.
  • Prevents fuel system corrosion.
  • Prevents gum and varnish from forming in the fuel and settling in fuel lines, fuel tanks, carburetors and injectors.
  • Keeps injectors and carburetors lubricated.

For best results, always treat fresh fuel before storage. Fill the boat tank when possible. Run the engine briefly, either in the water or on an engine flushing device, to allow the treated fuel to circulate through the entire fuel system.

For an additional level of protection, or for short-term storage, use Quicksilver Quickare®. It can be added to the fuel tank at every fill-up. Quickare helps control corrosion, gum and varnish build-up, while also warding off phase separation and stabilizing fuel for up to 12 months.

Corrosion Prevention

As a final step, apply Quicksilver Corrosion Guard Engine Protect rust inhibitor to non-painted and painted surfaces of the MerCruiser engine to form a water-resistant barrier that helps prevent corrosion during long-term storage. Corrosion Guard leaves behind a clear film coating that quickly dries to the touch and does not gunk up over long-term use.


Mercury, MerCruiser, Quicksilver, Quickstor and Quickare are registered trademarks of Brunswick Corporation. All other trademarks are the property of their respective owners.