I was out on the lake last week with Laidback & Gulfsouth33. We were coming into the lake through 9 mile cut & we hit something under the water. My speedometer quit working & was stuck on 45 MPH for a few days. It eventually dropped down to 15 MPH over the last few days but it still wasn't working. I did a bit of research & I found out exactly how my speedometer works. There is a small "BB" sized hole a few inches above the nose on the foot of my motor (Suzuki 150). There is a small rubber hose that is connected to the backside of that hole. The hose runs all the way up to the center console & plugs in the back of the speedometer gauge on the instrument panel. The gauge is actually just a pressure sensor. The faster you go, the higher the air pressure gets inside the hose & the needle goes up. I took a very small drill bit & cleaned out the hole on the motor the best I could by hand. I managed to get a bunch of sand, mud & some wood out of the hole. When water started coming out of the hole, I knew I had done some good. I removed the instrument panel & pulled the rubber hose off of the back of the speedometer gauge. I blew some air through the line with my air compressor & that seemed to clear out the rest of the line. I put it all back together & now it works just fine! Apparently this is a pretty common problem so I though I would share how I resolved it with you guys.