Yamaha Speed Incicator

[SommerTime]

I have a 2520XL with twin 150 Yamaha Motors. The Yamaha Speed indicator on the dash is erratic. I can compare the speed indication against my GPS Speed and I have a water paddle wheel speed indicator. Therefore I three speed indicators. The GPS and Paddle Wheel indicate the same within 1 mpg while the Yamaha Speed indicator maybe off 9 to 10 mph. Also, after running the boat in open water at 29 -30 mph the Yamaha indicator does not reduce to zero or low speed when coming into the dock, i.e. it indicates going into the slip at 22 mph and will stay at that speed even after the motors are stopped. Eventually the Yamaha speed indicator will show zero. The marina found a piece of wood in the petit hole on the lower unit which allowed the Yamaha Speed indicator go from no indication to erratic indication. My question is, is there a plastic tube that runs from the speed indicator to the lower unit, i.e. what is the circuit that makes the speed indicator sense the speed. Could there be dirt in that tube that gives it erratic indication. If so, how do you blow out the dirt? I want the the Yamaha Speed indicator to be fairly accurate so that if I loose GPS I can use Dead Reckoning to get home.

 

[Bryan 2530]

You should see a clear tube that goes all the way to the back of the dash.

Disconnect and blow it out.

 

[TimC2520]

I had the same problem last year. Mine had a fitting maybe 12" in front of the motor in the clear plastic tube. It looks like aquarium filter tubing.
I could disconnect there. It was filled with green, thick, slimy seawater. It was too thick to blow out, but I was able to suck and spit it clear. Just spit frequently because it tastes nasty and then rinse your mouth with a cold beer when you are done :mrgreen:

 

[miky2884]

Lol good advice

 

[Bryan 2530]

Suck and Spit? :shock:

 

[SommerTime]

Thanks men. I will look for the fitting but my motors are mounted on swim platform thus the 12" rule may not apply. But once I find it I will "suck and spit" then drink two beers.

 

[TimC2520]

Start where all of your rigging tubes come out of the cowling.
See if you can find the clear rubber tube and trace it up to your gauge.
You may find a barb fitting in the line somewhere, this will make it easier.