Some advice, if you please:
I have a 3.3hp Mariner as an aux engine. Bought second hand from a dealer about a year ago. As there's no room on my transom (4.5m Avon), I keep the thing lashed down horizontally in the back of the boat, above any water that might be washing about back there while running.
I've barely used it, and came to try it a few weeks ago and it wouldn't start. After much pulling it eventually got going, but was stuttering and would die if I opened the throttle. At the same time, the telltale was very weak to non-existent.
I decided to try my hand at fixing it, so bought a book
and watched a few YouTube vids which prompted me to order a new spark plug and successfully change the impeller (telltale issue now fixed).
I installed the new spark plug, but the engine wouldn't start at all. Imagine my confusion. Reinstalled the old spark plug and had same problem as I'd started with - the engine starts, but struggles when I apply throttle (in a tank in the garage). Once I've stopped it, I can't start it again for ages.
I'm at the very limits of my knowledge and wondered if anyone could throw some ideas at me to check. It's either that or take it to the outboard shop and fork out pretty much what I paid for it (£250) to get it fixed...
One tiny thing to add: I also bought a feeler gauge and have checked the gap on the spark plug is 1mm, which I believe is correct for this engine and is the same as the plug which was in when I bought it.
Thanks in advance,