Stumped... 5 hp Mercury 4 stroke very little power

[ASEAudie]

This engine was said to have ran just fine and then just stopped, it was not dealt with until later, which now is later.

I have tried everything I can think of so far, and this little guy barely runs at low idle and is very hard hard to get it to stay running then. Here is what I have done so far.
1) Ignition test good
2) Compression test read 65 psi
3) The gurgling sound at carb. When pulling the starter rope made me think of 2 things, clogged exhaust or valves not seating 100%.
4) I actually removed the engine and removed the cyl. Head and even removed both valves for decarbon and lapping, checked exhaust system, cylinder wall and piston for any slop.
5) Reassembled and no difference, removed carb. For tear down inspection, it is fine, I'm using a test fuel tank with fresh fuel.

This thing is getting my goat!
Any ideas?
Thanks

 

[ASEAudie]

Re: Stumped... 5 hp Mercury 4 stroke very little power

I kept at it; and found the problem. Sheared flywheel key! D#@& thing

 

[ASEAudie]

Re: Stumped... 5 hp Mercury 4 stroke very little power

The key is due to arrive at anytime, the shipping was more than the part.
If this doesn't fix this little turd, I'll probably just set it on fire! Lol, not really. It's gonna be fine afterwards.

 

[ASEAudie]

Re: Stumped... 5 hp Mercury 4 stroke very little power

Update, I installed the new flywheel key and she started and ran exceptionally well, conclusion is: If you have good ignition and good compression and it won't hit a lick when cranking; you might check the timing, wish I would have before all the wasted time, funny thing is; I even knew to do just that. The same principal applies to small air cooled engines that I've repaired for years.
Hopefully this might help someone down the road.
Love this forum, I want to give back, just as i have received from this forum.