Yesterday, while out for a nice five hour day-sail on Lake Champlain, I had the following event occur. The sail was over and it was time to head up the Otter Creek where my slip is located so I started-up the trusty Yanmar. After about fifteen minutes under power at about 2200 rpms, I wanted to increase the rpms to 2500. But when I increased the throttle the engine did not respond. It was as if I was being ignored 
So I throttled down to about 2000 rpms--it did respond to the throttle down I should add, and then I increased the throttle and it responded as normal up to 2500 rpms. Just to experiment I further increased the throttle and took it up to 2800 rpms. I believe this might have happened once before, but I'm not sure. Does anyone have any ideas as to why this happened? I read in the archives that maybe it is sludge in my fuel tank or a clogged screen or filter. Or maybe a sticking throttle cable? Or maybe I didn't let the engine warm up sufficiently before placing it under load? Any thoughts would be appreciated. S/V Elan '85 Hunter 25.5
So I throttled down to about 2000 rpms--it did respond to the throttle down I should add, and then I increased the throttle and it responded as normal up to 2500 rpms. Just to experiment I further increased the throttle and took it up to 2800 rpms. I believe this might have happened once before, but I'm not sure. Does anyone have any ideas as to why this happened? I read in the archives that maybe it is sludge in my fuel tank or a clogged screen or filter. Or maybe a sticking throttle cable? Or maybe I didn't let the engine warm up sufficiently before placing it under load? Any thoughts would be appreciated. S/V Elan '85 Hunter 25.5