Not a submarine engine

Had an incident last season where my Honda 5 HP outboard ended underwater at full revs. After thorough cleaning it started but has never held its idling revs. The carb has been checked and is clean, so my reasoning is that there could be a bigger problem caused by the intake of water. Any ideas on what I should check next?

It is possible that the valves and the pistons had a collision.

It is possible that you could have bent a valve or damaged something related.

You did not say if it runs ok at higher speeds....if it does, then maybe your problem is just the carburetor.

You said that the carburetor was cleaned but did you remove the slow speed jet #28 http://www.boats.net/parts/search/Honda/Outboard Engine/2005/BF5A5 LA /CARBURETOR/parts.html and clean that passage and jet. May be residue stuck in it to mess up the idle.

Also drain the fuel from the carburetor into a glass jar and make sure there is no water still in the system.

If all that is ok, then check the valve clearances and make sure the valves are moving freely.

Mike

Just one more thought. The valves and pistons would have collided only if the flywheel key is sheared. Not sure where my head was. It is not unusual for the key to shear when the engine impacts something.

Thus, if the timing is off, the idle will be bad or none existent. Normally, you will have to pull the flywheel to check the key to be sure.

Mike

I would still check the idle jet in the carburetor before you get too much into things.

Mike

In addition to the good advice above, I would only add that if you do start to "dig in" to find an internal issue, I would begin by checking to see if you may have bent a pushrod. Those will be the weakest link in this valve train if you got into a hydrolock situation with the engine ingesting water while running. Just take them both out and roll them on a flat surface, like a glass tabletop, and look for any "wobble".
Good luck.

Thanks for the advice, I omitted the fact that the engine runs well at any speed and even starts good so I will check the the flywheel key and if that is good I will check the pushrods.If both are good then I will probably have to go deeper. I will let you know the outcome.

It is a fairly heavy flywheel and it may well have sheared they key if it came to a sudden stop.---Simple to check that.