Spark plugs for a 1997/8 Selva 9.9 (in fact most models) is BOSCH W7B or CHAMPION L 87 or equivalents. 20thou gap is recommended but anything close except a dead short should at least fire.
A copy of the parts manuals is on my server here: http://www.avonsearider.co.uk/pdf/Se...S1997-1998.pdf
Might be useful for wiring diagram....
Owners manual here:
Check out the starting procedure!
A compression test would of course be handy and should be over 100psi and within say 10% of each other although even poor compression engines will at least fire up even if they wont run well. When trying to start before putting fuel in the bores were the plugs wet?
I'm going on holiday now so will not be posting much over the weekend.