Mercury service bulletin for proper spark plug

[dieselsmoke]

I wanted to post this service bulletin I found. I was planning on putting the same spark plugs in my 2007 sea ray 185 mercruiser 4.3 carb'd that I removed, but it turns out this bulletin recommends otherwise. The plugs that I took out are 41-993, which is the plug it shipped new with. I didnt think much about putting the same ones in however this bulletin says to go with mr43lts. The 41-993 ship with a gap of .060 but the motor needs a .045. Because of this gap difference they recommend the mr43lts as the replacement part. I did have an issue with my motor dieseling last year and wonder if this may have been a part of the problem. Here's the link

http://ww2.justanswer.com/uploads/ROCKETBOAT/2008-12-09_042519_SPARK.pdf

 

[BillK2632]

The MR43LTS is what came in mine and what I have always used. I still have a deisel problem occasionally. Need to ensure idle is set properly and throttle is closing completely.

 

[dieselsmoke]

My dieseling problem is gone this year. but I also gave it a full tune up, had the carb sent out and redone, removed the old gas, found it was running cold due to a stuck thermostat. Along with the regular maintenance of new filters and oil my dieseling problem has been resolved. Setting the idle to 650 is also key. I think the dieseling would be more common when several problems come together but I would guess a plug with the wrong gap couldn't help

 

[Espos4]

Thanks for posting the bulletin.

When I come across these, I print them out and put them in my "boat" binder.

Always good to have access to any reference material and updates.

 

[Searayguy185]

I wanted to post this service bulletin I found. I was planning on putting the same spark plugs in my 2007 sea ray 185 mercruiser 4.3 carb'd that I removed, but it turns out this bulletin recommends otherwise. The plugs that I took out are 41-993, which is the plug it shipped new with. I didnt think much about putting the same ones in however this bulletin says to go with mr43lts. The 41-993 ship with a gap of .060 but the motor needs a .045. Because of this gap difference they recommend the mr43lts as the replacement part. I did have an issue with my motor dieseling last year and wonder if this may have been a part of the problem. Here's the link

http://ww2.justanswer.com/uploads/ROCKETBOAT/2008-12-09_042519_SPARK.pdf

Mine use to diesel every now and then until I adjusted the idle speed down to 600 exactly. you want to do this when the engine is at operating temp. Mine used to be set to 650 and after talking to a guy at Mercruiser tech support he said they updated the info and recommend setting it to 600. After that it has never dieseled once! Hard to believe that only 50 RPM's could make a difference but it did.