Anna Kathryn

the yamaha fuel gauge is reading full all the time. checked the wires and they look good, took the sending unit out of the tank and moved the float up & down with no change to the reading on the gauge, it still registered full.....
please help.....

timing

While you have the sending unit out -
Put an ohm meter between the sending unit terminal and it's moutning plate.
Move the float arm the full range - should see ~30-240 ohms.
If that's what your seeing, sending unit ok.

Disconnect the sending unit lead at the back of the gauge, should goto empty.
If yes, gauge is likely ok.
(On my boat, the wire from the fuel sending unit is pink).
Could do a super thorough test of the gauge by putting a variable 30-240 ohm resistor load to gnd.
Moving through that range of resistance should move the gauge accordingly.

If the sending unit and gauge test ok, likely the sending unit's wire is shorted to ground somewhere.
Unless you find a obvious and definite short, start thinking new wire from sending unit to gauge.
Could likely use the old wire to easily fish the new one.

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