Re: Please help - water issue
TUBES
This should all be a fairly simple fix. Trace the two tubes as follows:
One should go from the speedo to the pitot tube mounted on your stern. Some boats have a pitot type deal built into the lower unit. I suspect yours does not. This tube usually shoots water everywhere when you are moving at a high rate of speed if it is disconnected. Trace this tube and check for any pinches in the line. If this tube is pinched, your speedo will not register properly.
The other tube will most likely go from a water pressure gauge to a nipple usually found on the top stern side of your motor. Look under the cowl. The water pressure gauge has numbers on it. Most likely you have the water pressure gauge hose connected to the speedo if it is reading 20mph when not moving. If it reads this with the motor off then replace the gauge. This tube will shoot water if disconnected. The more then engine revs, the higher the water pressure will get and so the more water will come out of this tube if disconnected. This should happen whether you are moving or not.
One more note on these tubes. If I am not mistaken, the standard for attaching these tubes to your gauges and pitot/motor respectively is to use a small zip tie so that the tube cannot possibly be pulled off of the nipple it is connected to. Every boat I have ever worked on has been attached in this manner.
GAUGE WIRING
The other gauge that you describe has an up and down arrow on it should be your trim gauge. You have to check your wiring on it but usually the sending unit wire is tan or dark brown with a white stripe depending on the motor and harness that is in your boat. The tan or brown/white should be connected to the "S" or "SEND" terminal on that gauge. The tan wire should come from your harness. That gauge should also have a ground wire that is black connected to the "G" terminal. It will also have (or should have) a purple wire that connects to the "I" (ignition terminal). The purple wire should have +12V on it when you have the key in the run position. You should also have one more wire that is blue that connects to a terminal by a bulb.
Your gauges should be wired as follows:
The purple wire (+12V ignition) will come from the wiring harness or ignition depending on your exact set up to one gauge and then you will use short jumper wires with ring connectors to go from gauge to gauge so that all your gauge will have a purple wire coming from another gauge connecting your "I" terminals in series with exception of your last gauge where the purple wire will terminate and your first gauge which will have the purple wire come from the harness.
The black wire (ground) will be wired identical to the purple wire but the connections will be made to the "G", "GROUND", or "-" terminal.
The blue wire (+12V for Lights) will be wired in the same manner but the blue wire usually comes from the ignition switch itself straight to the gauges so that the gauge lights turn on with the ignition or it is tied directly into the hot wire for your nav lights so that when you turn on your nav lights the lights on the gauges turn on and then will be wired to the rest of the gauges in series in the same manner as stated above.
Your tach will usually have a grey wire that comes from the harness to the terminal marcked "S" or "SEND". The other terminals on this guauge will be wired in the sammer manner as above.
Most gauges have the "I" (Ignition {purple wire}), "G" (Ground{black wire}), and an "S" (Send{Color varies [grey = tach],[tan/blue and sometimes just tan or brown/white = trim]})
This link should help with visualizing the wiring.
http://ww2.justanswer.com/uploads/JeffGr/2011-07-07_032111_instrumentpanelwiring.jpg
Good Luck bud!
Also, there should never be any water in the pitot tube inside the boat. The tube should have nothing but air in it except for maybe a foot or two above the actual pitot mechanism outside the boat.
