'91 Gt 200 possible problem

[stratos976]

1991 Johnson GT 200 m/n VJ200SLEID s/n 02000222


I took the plugs out this evening to check and replace them. I noticed on the Port bank of cylinders, Bottom plug the color was quite different from the rest.

All ther other plugs had a tan color to the electrode and damp enough to be shiny, but not what I would call wet........ The plug in question, the electrode was dry looking and a charcoal gray color...not black carbon or deposits on it just a dark grey color.

Was this cylinder not getting fuel???? What else could cause this? I just ran it yesterday, fishing a tournament, had a little trouble starting it and noticed a stutter every now and then when idling, that was the reason for pulling the plugs , seemed to run ok on top though.​

 

[stratos976]

I posted this earlier, but now I see it in the Merc board and it wont let me reply back to it over there.

I did a comp check today (cold)
port starboard
75# 74#
70# 78#
75#(cyl in question) 70#

numbers seem low all the way around, I have not checked spark w/ light yet or taken airbox off and checked carbs.

 

[Boobie]

You may want to have the mtr warmed up and check the compression again. You also may want to do a good de-carb on it and then re-check the compression again.

 

[nicknack2]

It is my understanding that many of those 200HP motors have low compression heads to compensate for the low octane gas at the pumps, then yielding low compression readings, how low I’m not sure, but one should be concerned more with the numbers being within 10% of each other than the reading itself, as far as the plugs if you were lean at idle the motor would sneeze, and spark plugs would have a dry black color, tan color its fine I think.