Yamaha four stroke speed sensor

[RandMadeRods]

Can anybody tell me where the speedmeter sensor is on the F150? My boat doesn't have the speed wheel type under the boat some so I can only assume it's with the motor(s) somewhere. For info, I have twins. Worked fine yesterday until we came back in at which point the speedo would max out at 3 mph which also resulted in a false odomter reading. I guessing that the sensor might be bad or possibly got debris in it. Thanks, Randy.

 

[Megabyte]

Don't know about the F150, but my OX66 has a very small (about 1/16th of an inch) pitot hole on the forward edge of lower leg of the motor.

It doesn't take much debris to clog the hole, but it is easilly cleaned by using a simple twist drill bit, rotated into the hole with your fingers to clear the obstruction.

 

[grouperjim]

Like Kevin said, it is small pitot opening (water pressure sensor) on the leading edge of lower unit.

They all get fouled every so often. While underway, the easiest way to get it working again is to stop the boat and do a quick reverse to let the prop wash clear the pitot sensor.

jim

 

[RandMadeRods]

Thanks guys for the info. I did actually stop the motors and tried the reverse thing but it didn't do anything. I also turned them off and on but no fix. I'll check to see if a small piece of seaweed or something got in there. Randy.

 

[Porkchunker]

1/16" drill, twisted in your fingers is sufficient to clear any debris. Don't chuck them in a power drill!!!!

Mine need clearing once or twice a year, and I've gotten to the point where I set up the GPS/chartplotter to display the speed rather than rely on the Yami speed sensor. Sometimes you get a partial blockage, and the GPS will read 24 mph, and the Yami will read 14.

 

[goinsfishin]

The pitot tube sensor is the weak link on Yamaha's. You can clear it with a drill bit as mentioned above, or some heavy mono (80# +) will also do the trick. Another source recommended taking the tube off the back of the speedo housing and blowing it out with compressed air.
Mine gets clogged regularly running on the Crudapeake Bay.
I've gotten to the point where I don't even worry about it and use the GPS for both speed and odometer, it also much more accurate.
If you do your own maintenance, be very careful when doing the water pump impeller to reconnect the tube properly with tie wraps, otherwise the tube will work loose and the speedo wont work at all (experience talking).