Merc 850 plug and wire check

[1kickpic]

I stored my 4 cylinder engine and noticed one of the plugs was black (and looked unused). the other three looked fine (no black residue) and cleaned up well. the plug wire also looked rusted where it connects to the top of the plug. is it possible that this cylinder is not firing? What's the best way to test to see if it is firing (without electrocuting myself)? the engine runs fine in the yard, and i don't notice a lack of power on the water.

 

[joblo33]

Re: Merc 850 plug and wire check

take the plug out and rest it against a bolt on the powerhead with the plug wire on the plug. Crank the motor and see if the plug sparks. Make sure the threaded area is grounded on the bolt when doing this.