Yarcraft's Tip works again- 15 Merc 2-str
About a year back Yarcraft91 suggested that anyone trolling alot with the little 9.9 and 15 Merc 2 strokes should clean out the exhaust relief holes now and then since they tend to get a carbon build-up in them. I checked my 15 at the time and discovered that my motor has 2 relief holes, one is big- like 1/4 in or so, the other is small- less than 1/8 inch. I found some crud in the small hole which I cleaned out with a twist drill held in my fingers. I noticed that the motor did idle a bit better after this. Yesterday I got a call from my Daughter- who also runs a 15 Merc on a 14 Starcraft and does some trolling. Her Merc is a 1999 model which she bought used, and has run well for 2 seasons with no maintenance needed. She said the motor no longer would idle, even with the external idle speed knob turned up all the way- it would start but then stall unless you added some significant throttle. Other than not idling, she said it ran just fine and started on the first pull, just as it always has. I remembered Yarcraft's tip and had her check the relief vents- and sure enough, when she tried to clean out the small hole it was blocked solid and some water even came out that was trapped above the relief. After this she said it was a completely different engine- and would idle just fine with the idle speed knob turned to its lowest setting. Daughter says "Thank You" to Yarcraft for the tip- and to me for remembering it after a year!