dieseling - merc 190hp

[swilson]

my 1800 sr3 is starting to do this a little. It will run on for 15 to 30 seconds at this point. I see that dieseling is common for this engine. In other posts it was indicated that the dieseling can last longer. How do you stop it if it starts when you are on the water? I am really not interested in taking the boat to the dealer this time of year to adjust the engine. How bad for the engine is this problem?

[seapuppy]

dieseling is usually caused by predetonation....the cylinder is hot and causes the gas to ignite early.....the best thing to do is adjust the carb a bit rich..not alot..this will help keep the cylinder a bit cooler...also let it run at idle for a few minutes before shut down...if it diesels on you ...turn the key back on and let it idle for a few minutes...then shut down...
when you get a chance..have the timing checked and adjusted if off....if that doesn't help...run a slightly cooler plug.....

[MCSR3]

I had the same problem with my boat. When I took it in for the 25hr. service they adjusted the carb. They said it wes idling high. I have taken it out 3 times since then with no problems. Hope this helps. 8)

[jimbenton]

1. try running cooler plugs if possible

2. correct motor tuning is essential

3. clean air filter/flame arrestor

4. do not attempt to turn off motor immediately after a full speed run
give the motor time to cool a little.

5. I ve heard some running the blower if the engines are in a bay to cool
the air around the engine prior to turning it off.

my three cents...lol