Late last night, I went to check on my one 1500 gph rule pump with automatic float. My 1972 22-2 does not self bail (stern too heavy with the 200 hp Johnson back there, so drain holes are below water level), so I check how much water there is, and make sure the auto float works. Well, there was a deluge during the day, and the water level in the bilge was quite high. Obviously, the pump did not come on automatically, so I turned it on manual (?) and out came a lot of water. I then checked the operation of the float switch, and, with the pump set on auto, I lifted the float up to activate the pump - nothing happened. I tried it again on manual, this time, it won't turn on anymore. Picture this, this was now after midnight, everyone fast asleep, and I am on the boat with a light hooked up to shorepower, trying to figure this one out. Checked all connections, to see if a wire fell off - everything good and tight. Fuse - filament ok, but I put in a new one anyway. Cut off then re-connected the main red (+) and black (-) - still nothing. I did notice both red and black wires had black stuff - like soot - like moisture got inside the connections. I cleaned the dirt off, and re-connected. Still nothing. I was not going to bed with the pump not working, and if there's a heavy downpour that night, the boat might sink - no way. After 2 or 3 hours of this, I decided to just connect the main red and black to the battery using fresh new wires - VOILA - power back on and the pump works. Lesson learned - keep wires from moisture, and the black (neg) wire can be the culprit if something does not work. I'm not very good with electrical matters, but there must be a way to check connections using a meter to eliminate the guesswork - and save time. Can someone give me some pointers? Thanks.