Thanks Crosbyman,
I went back and read this in your reply.
"just as info... the large round exhaust skirt above the water pump sometimes will let fumes go up into the powerhead area and cause engine suffocation as fumes get sucked in the carb."
This could explain why, the last time I had it in the water 20 years ago +/- a few years. After putting in new plugs and an impeller and it running good in a drum of water with the cover off. I had to run it with the choke on while out on the water. I was thinking Carb. problems so maybe. maybe not.
Of course the part is unavailable, but I sure there is one somewhere or a fix if I find this to be a problem.
actually running with the cowl off is good in the sense that more fresh air will reach the top mounted carb ... yet running in a drum could certainly cause carbon monoxide death...to the engine
notwithstanding other issues running with the choke is imho more indicative of a dirty carb the bottom HS jet must be sqweaky clean as well as the LS cct under the cover plugs. Leroy explains all this and the fact the
kits do not include... a small round plastic insert in the LS drip chamber which generally get mangled when taken out . Both LS and HS circuits must be clean 100% .
Don't assume the existing skirt is bad till everything above it is checked out incl . point condensers coils carb ls/hs circuits. Try lake running with cowl ON and OFF to compare performance . If it is a CO2 issue cowl OFF will prove it
One 9.5 I picked must have been so bad the previous owner performed a cowl lobotomy (2") just above the carb to let fresh air reach the carb.
I patched it all up but I have yet to run it... if it dies on internal CO2 I will try shooting some insulation foam in a can to fill the area just above the skirt...to stop the CO2 migration ..... skirts being unavailable.
if not cured with foam ......the spare parts bin awaits ....
p.s. there is a good 2 part series utube on the 9.5hp carb service
www.bing.com