mercruiser 4.3 lx problem on shutoff

davidsp

Cadet
Joined
Sep 23, 2013
Messages
29
hi little problem noticed on my new boat... when i run like normal then try to shutoff the engine using key off position

the motor is like keep running 2cylinder for 3 explosion then shutoff any idea?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: mercruiser 4.3 lx problem on shutoff

It's called 'dieseling' or 'running on'... The only way to ensure it doesn't happen, is to let the engine cool off for a few minutes before turning the key off....

BTW... It's a bad thing! As the engine is trying to keep running, it can suck water back into the cylinders and hydrolock the engine...

Chris....
 

NHGuy

Captain
Joined
May 21, 2009
Messages
3,631
Re: mercruiser 4.3 lx problem on shutoff

Also, check that your idle is nice and low. When warm you want 775 in neutral or 650-625 in gear. It should shut off well if cooled down and idled low.
 

davidsp

Cadet
Joined
Sep 23, 2013
Messages
29
Re: mercruiser 4.3 lx problem on shutoff

How many minutes before shut down i have to wait.. i wait 1min and its still apening... is it normal
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: mercruiser 4.3 lx problem on shutoff

It could take as long as 4 or 5 minutes... You're trying to dissipate a 'heat soak' condition.
 

davidsp

Cadet
Joined
Sep 23, 2013
Messages
29
Re: mercruiser 4.3 lx problem on shutoff

Ok corect me if i wrong.. i need to wait 5minute before shutoff engine each time im gonna anchor?
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: mercruiser 4.3 lx problem on shutoff

You could idle up to your anchor point... Use the time it takes to lay anchor to be your cool down period...
 

Bondo

Moderator
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Apr 17, 2002
Messages
70,468
Re: mercruiser 4.3 lx problem on shutoff

hi little problem noticed on my new boat... when i run like normal then try to shutoff the engine using key off position

the motor is like keep running 2cylinder for 3 explosion then shutoff any idea?

Ayuh,.... Usually, a Complete tune up, 'n carb adjustment will cure that dieselin' condition,...
 

Fastatv

Petty Officer 1st Class
Joined
Sep 28, 2013
Messages
258
Re: mercruiser 4.3 lx problem on shutoff

Also, check that your idle is nice and low. When warm you want 775 in neutral or 650-625 in gear. It should shut off well if cooled down and idled low.
What NHguy says. To reiterate, what is the idle speed when you shut it off? And, if your running hard, then coming off the plane, the engine can warm up a bit. Look at your gauge, whats the temp when you turn the key off.
 

Volphin

Lieutenant
Joined
Jun 5, 2011
Messages
1,405
Re: mercruiser 4.3 lx problem on shutoff

Could be that your timing is too far advanced. Bump it back 2-3 degrees and see if that helps.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Re: mercruiser 4.3 lx problem on shutoff

That idle speed is too high. You need it down to between 600 and 650 (and that is in neutral)...
 

Volphin

Lieutenant
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Jun 5, 2011
Messages
1,405
Re: mercruiser 4.3 lx problem on shutoff

Ayuh, retardin' the timing will do that. ;)
 

modsrx

Petty Officer 3rd Class
Joined
Aug 13, 2007
Messages
86
Re: mercruiser 4.3 lx problem on shutoff

Ayuh, retardin' the timing will do that. ;)


put higher octane gaz it will solved your problem ...not sure if u run regular gaz in it or ?? to mutch timing will make that problem and not enough octane will make the same problem ...u to choose how u want to solved the trouble
 

modsrx

Petty Officer 3rd Class
Joined
Aug 13, 2007
Messages
86
Re: mercruiser 4.3 lx problem on shutoff

and make sure that engine is not running very hot ....
 
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