Things You'll Need:
- Basic tools
- Brush
- Wire
- Compressed air gun
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Step 1
Identify the inlet port for the speedometer hose. Boat speedometers use an inlet port on the motor or on the transom bottom (under the rear or stern of the boat) to measure speed. Moving water flows into this port and compresses the air inside the hose. The higher the force of the water (due to increase in speed) the more compression and higher speedometer reading. If you can't find the hole, look on your motor documentation or ask your dealer where it is.
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Step 2
Inspect the area around this port hole. Free it of algae, dirt and debris which could be blocking the intake hole. Use a wire, a brush or a screwdriver to dislodge the debris.
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Step 3
Test the speedometer by running your boat at a safe speed. If the blockage was removed, then the speedometer will show your boat speed. If not, go on to step two.
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Step 4
Raise the boat out of the water, or tilt the outboard out of the water so you can access the inlet. Using a compressed air tank, and air gun, blow some air into the inlet. Watch the speedometer. If it jumps up, then the inlet is free from debris. If not, there is a blockage in the tube.
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Step 5
Continue to clean the inlet using a wire with a brush head. Remove all dirt inside the tube until the speedometer tube is completely clean. Then retest the boat speedometer.
