I have a 06 115 Optimax. I have had a rough fast idle since last summer. Every time I start the day its fine but throughout the day it gets worse. Every trip is like this. Its worse if I have to idle a long way. Like a no wake zone or graph an area for a while. Has no problem getting on plain or full throttle. I took it to a mechanic and he said a spark plug was the issue. Went out the next day and it ran great. Never missed a beat. That was last weekend. Took it out yesterday and ran great the first 3 hours than the miss at fast idle came back. What could cause the spark plugs to fail? The mechanic replaced all three spark plugs and it ran great the first time but the second time its starting to miss again.
Also, my bulb seems to not harden when I pump it. It will fill some but doesnt seem to fully fill. This probably plays into it as well.
Actually ran over to get my serial number: 1B481011
Thanks