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Author	Topic:   Strange Spark Plug failure
Fishmore	posted 04-06-2009 01:10 PM ET (US)      I took my Montauk out this weekend on SF Bay for some Halibut fishing. I am running a 94 Mercury 75HP Oil injected 3-cyl 2-stroke. When I first started the motor it started running a little rough and had an occasional backfire or miss on one cylinder and then stalled at idle in neutral. I placed it in gear and it idled fine no backfire. I knew this was strange but last month after replacing my shift/throttle control I had adjusted the idle which also adjusts the timing and I figured I must have set the idle too low. So we took off for a day of fishing and the engine performed fine except I was about 3mph off at full throttle and when in neutral it would do the miss and stall thing. Strange thing is I could idle in gear for hours with no backfire and smooth running. When I got home I started to check the idle circuit and then I decided to check the spark plugs. I found that when I pulled the wire off the number one plug the electrode came out with the wire. No damage to the ceramic or anything the electrode just had broken off about one inch down the shaft. I have never seen that before but a new set of plugs $6.32 for all 3 solved the problem. Plug was an NGK BUHW-2. Just thought I would share.
fourdfish	posted 04-06-2009 08:19 PM ET (US)             Although not common, I have seen this before and in other types of engines as well!

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