Turn off the key, but engine keeps going.... - Maxum Boat Owners Club

valleevessel · 07-06-2010, 09:45 PM

New to the boating world--very new, so this may seem like a dumb question but we bought a 1999 1800SR and have noticed that sometimes when turning it off to load up tubers/boarders, we turn the key off but it keeps "clug, clug-clug, clug, cluging' and then finally dies.....does anyone have any advice what causes this or what to do to stop it? With kids around I don't want to risk the engine not shutting off right when we want it to.

ss3964spd · 07-06-2010, 10:22 PM

1st, welcome aboard. 2nd, congrats on the boat and becoming boaters!

3rd, it's called dieseling - and it has the potential to ruin your day. You need to get it in for a tune up, especially have the timing and idle speed checked, and ensure you are using the correct octaine gasoline.

As a temp solution try to turn it off while in gear, there may be just enough drag from the drive to stop the engine immediately.

Dan

seapuppy · 07-07-2010, 05:34 AM

what dan said..but one step....let it idle a few more minutes before you shut it off...granted that there are problems when trying to get tubbers on board but the try and let it idle a bit more to cool off...
another thing to concider about the tune up is maybe have the mechanic check the temp of the plugs..if they are too hot..they will cause dieseling...so a colder plug MAY be in order.........
also use an octane booster......if your running regular pump gas..it may need to have a higher octane ..which lets the engine get the same amount of pwr for less fuel used...

SP

hybris1 · 07-07-2010, 06:42 PM

My boat was doing this when it was fouling the plugs. The carbon would stay hot and ignite the fuel. My temperary fix was to use octane boost. It stopped the dieseling. I found later that the plugs had the wrong gap and would not always spark on idle causing a rich condition and fouling. I changed the gap and that fixed the problem.

jreidg3 · 07-09-2010, 10:38 PM

I have the same issue when running wide open or under full acceleration and then full stop. I find if I let the engine idle for few seconds before cutting it off or more slowly decelerate I find that it is less likely to happen.

deanries · 07-21-2010, 02:38 AM

The previous posts were all right on but my quess it's probably the spark plugs. I have always kept a spare set on board my 1992 1800SR just in case. I also fill up after each outing with at least mid-grade gasoline. With more and more ethanol being added the octane booster might become a must for all of us. Hope the problem is resolved by now, summers always seem too short. I reside in Waterloo, Il, where's Ogden?
"Go Big or Go Home"

jfleece03 · 08-11-2010, 07:07 AM

I always put in the mid grade gas, but no octane booster. How often would you guys suggest putting in the octane booster?

seapuppy · 08-11-2010, 01:57 PM

Hi Jfleece03
welcome to the zoo...if your going to use octane booster,,,your going to want to use it at every fill up...

SP

ss3964spd · 08-11-2010, 02:29 PM

If the engine runs fine on mid grade there is no benefit/reason to use octane booster.

ed & inge · 08-11-2010, 06:35 PM

i believe the mercruisers run the best on gas with an octane higher than 90......here we have 95 and my 5.0 ltr 260 HP sewing-machine runs nice.......

greatz, ed

racer2c · 09-08-2010, 09:41 PM

Mine has always 'dieseled' (sic). Had the dealer look at it a few times, only to replace the plugs and tell me its a bad characteristic of that engine. So I simply got accustomed to letting it idle for 60 seconds before I shut it off. yes, that frustrates the wakeboarders I pull...but its better than ruining the engine.