Boat will stay momentarily running after key off?

[BrodyO]

I've got a 1996 Larson with a 5.7GL, 2bbl Holley Carb, Non-Vortec. Once and a while when I shut the key off the engine will spit and sputter for a few seconds afterwards. Ideas as to what is the problem? Ignition not shutting off?

 

[alldodge]

Idle set to high, timing incorrect, engine running to hot, to rich fuel mixture

 

[poconojoe]

It's called run-on, pre-ignition or dieseling. Look it up on the 'net. It used to be more common in cars years ago.
Check all the things that ALLDODGE suggested.

 

[Scott Danforth]

in a boat its bad, because the last thing you hear is the motor running backwards, sucking in water from the exhaust.

 

[poconojoe]

Very important point from Scott...I forgot about that. Sucking water into your engine's combustion chambers IS very bad. Can cause hydro lock which can cause serious damage.

 

[BrodyO]

Hydrolocking would for sure be terrible! My idle is set a little high, about 900 rpm in neutral, I'll lower that. Otherwise I'm going to rebuild the carb to make sure all of my mixtures are correct.