|I think this discussion item may have solved a problem I have had with my 9.9 Yamaha 4 stroke in Jezabel. At low speed, even since new, the motor would sometimes run unevenly and then cut out - usually when manouvering in congested boat harbours - but would restart happily. The build-up of fumes in the engine well may be the cause. The engine runs perfectly most times, and I had suspected contaminated fuel or an intermittent electrical fault - both unlikely as the fuel is often refreshed and the motor not too old. Some other corroborating factors pointing to fumes in the well: 1) the poor running is only at low speed 2) often in boat harbours (still conditions with less wind and less movement to flush fumes) 3) the newer grey 9.9 Yamaha 4stroke is physically larger than the older 1990 white model giving less space for airflow around the motor [fitting this motor was a p.i.t.a. as most dimensions were not compatible with the older 9.9 Yamaha but that's a saga in itself!!!] |
So thanks, Greg et al for your interesting comments - I may try an experiment to carefully / partially reduce the airflow into the well and see if I can reproduce the problem. If so, I can then plan to remedy it.
On another point - I'm a bit passionate that the motor be fed cooling water. The Yamaha tell-tale is virtually not visible when it's in the well. To help with flushing the motor ["Have the earmuffs fallen off yet?"], and to help detect any plastic bags wrapped around the skegg, I have extended the Yamaha rubber tell-tale pipe with a brass joiner and added another pipe and nipple. These emerge from the motor via the front rubber grommet. The (swivelling) tell-tale then pumps out into the cockpit, points straight up, or points into the well depending on what I want. The old 9.9 Yamaha provided the necessary "organs" for this extension.