How to Unclog a Pitot Tube on Mercury

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When the pitot tube that provides water pressure information to run your boat's speedometer clogs, it's an annoyance. While the Mercury SmartCraft display is able to extract speed data from a GPS receiver on boats so equipped, if your boat is not equipped with a GPS unit, it will have no source of speed information. You can avoid the fines you might incur from exceeding boat speed limits, where imposed, and keep your speedometer working properly with a compressor and a small piece of wire.

Items you will need

  • Compressor

  • Thin piece of wire

Inspect the pitot tube opening, located at the leading edge of the lower unit. To clean debris from the pitot, press in on the speedometer hose junction and pull the hose out. This opens both ends of the tube, and allows you to blow compressed air through the pitot with low-pressure compressed air from a compressor.

Run a thin piece of wire through the pitot tube to ensure it's open, and to ensure it drains completely if wet debris was trapped inside.

Reconnect the pitot tube before storage.


  • "Mariner/Mercury Outboards Repair Manual, 2.5-250 HP, 1990-2000"; Seloc Marine; 2007

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.