What is this!!??

[Zac93218]

20130526_182248.jpg
So I am having a ton of problems with my boat not wanting to start to not wanting to stay running. There is power wire and a ground wire running off of this thing and the power wire is connected to one of the two small posts on the starter solenoid. my fuse kept blowing when trying to start the boat. after replacing the fuse the wire was getting extremely hot and started smoking. We took it off and the boat will start but will die as soon as the key returns to the on position. Basically I was wanting to know what the thing in the picture im point at is and what does it do?

[chpthril]

Looks to be the neutral safety switch. That may prevent it from cranking over, but will not have any effect on engine performance.

[Zac93218]

ok i thought thats what it was but wasnt sure. It doesnt seem to be working right anyways so im going to bypass it for now. i got everything figured out for now. seems to be running good but my electronic vacuum advance thingy gigamabob doesnt seem to be working properly either but the boat is running fine without it....?

[chpthril]

Just be aware that bypassing the NSF will allow the boat to be started in gear.

When you say "not wanting to start" do you mean not crank over as in starter not engaging, or the starter spins the engine over but it will not fire up and run? Diagnosing either will take you down different paths.

[boatwakes]

Hey ZAC!!!! There is NO GROUND WIRE on that switch!!! Those two wires are the signal wires carrying a positive 12volt signal to the start side of the starter. There is only power to them when you turn the key to "start". The signal is then passed to one side of the switch and if the transmission is in neutral, the other side sees power and sends the signal directly to the starter. If someone hooked up a ground there, that is totally incorrect. The wire colors should be yellow with a red stripe on both sides. If you need some more help with the engine, post as much information as you can, any details of the situation too even if you think they would not pertain to what's going on with the engine.

[boatwakes]

After re reading your post try this: check for power at the ignition coil when the key is in the "on" position (do not use the negative side of the coil for ground). If there is none, determine why. The purple wire on the coil should show around 9-10volts when the key is on. But when you start the engine (you must be carbureted to have the following wiring set up) the coil sees 12v from a wire connected to the outside small post on the starter, this is to aid in starting spark voltage. When you release the key that signal goes away. If the engine stops, you have one of two conditions: either a break in the wire between the key switch and the ignition coil or a bad key switch. To test the key switch, turn the key to "on" and test the "I" wire on the the back of the switch, it should read 12v or whatever your battery voltage is at the time. If it reads voltage there and none on the coil then there's a break in the wire. If it doesn't have voltage at the "I" but it does at the "B" behind the switch (with the key on) then you need a new key switch.
Keep us posted.