Detecting water intrusion Merc 1150

[monk-monk]

Couple off observations: when i checked my spark plugs, cylinders 1,2,3,4, and 5 are always wet with gas but #6 spark plug is shiney and clean all the time! I have rebuilt the entire fuel system and i remember when i disassembled the fuel pumps, the lower pump and hose feeding to the the bottom carb appeared to be dry like it never had gas going through it. Also when i stop the motor, i see a lot of gas in the water around the engine.

 

[AMD Rules]

Re: Detecting water intrusion Merc 1150

Good chance you lower crank seals are leaking some water into that bottom cylinder, especially if the plug appears to be 'steam cleaned'. A little water is harmless. A lot of water is a big problem.

To check your bottom carb for fuel supply, try placing a small 3" flat drywall knife (or similar item) over the carb throat while its running. You should see it drool fuel out that carb throat. I'm assuming you rebuilt the fuel pump when you had them apart.

Some people may disagree, but... the best way to 'read' 2-stroke plugs is to run the motor at planing speeds on the lake, then turn the ignition off. Doing this safely is paramount, as you will lose the ability to steer effectively, ad you'll want to coast somewhere near to shore where you can comfortably remove the plugs without risk. Reading plugs after idling as slower speeds for long periods doesn't really give a good indication of what the plugs are doing under load.