Yamaha F90C Speedometer Port

[Mike M]

The speedometer on my Lund stopped working late last summer. I'm told that it gets it's speed input from the motor (2004 Yamaha F90C) from a pressure sensor on the front of the lower unit. As the boat sat in some very silty water most of the summer, the pressure sensor port may have well become plugged so that the speedometer is not getting a proper feed. Does anyone have any suggestions as to how I might find, check and clean the port? Is there a pressure line on the motor that I can unplug and blow(?) into to see if I get any response from the speedometer? Any suggestions welcome. I can't find anything on this through Google and the owners manual is useless. I really don't want to have to shell out for a shop manual for something that might be a very easy fix.

[lifeisfun]

Try disconnect the tubing on the gauge and blow the tubing with compressed air. There was couple discussions about that on iboats.

Search link on iboats:
http://forums.iboats.com/search.php?searchid=3424317

[Mike M]

Thanks Lifeisfun, I checked out the link and the forums provide some good advice and discussion. Just the kind of info I was looking for. Cheers

[lifeisfun]

Good luck !

[fisher]

There is a very very small hole(like a pin hole) in front of lower unit, try blowing it out with some air, if that doesn't work , try cleaning it with a very small wire, like a single strand from downrigger cable or brake wire, you'll know when it clears, some water & gunk will come out,
DO NOT use a thicker wire then the hole because it may enlarge it and that will screw up the speed calibration.

[fisher]

There is a very very small hole in front of the lower unit, try blowing it with some air, if that doesn't work, get a single strand from downrigger cable of brake cable and try that, you'll know when it clears because some water and gunk will come out.
DO NOT use a thicker wire then the hole because that might enlarge it and screw up the speed calibration.