1999 Mercury 25 hp 2 stroke popping noise on muffs?

[Expidia]

When we were winterizing it and letting it running on the muffs ever 30 or 40 secs there would be a small pop (like a small backfire). Is this normal? I don't think it pops in the water when underway.
Thx

 

[jakedaawg]

I would think it's fine and your just hearing it on muffs because when in the water the sound would be muffled by being below water.

 

[Expidia]

I would think it's fine and your just hearing it on muffs because when in the water the sound would be muffled by being below water.

Thx for your response :joyous:

 

[Expidia]

over the 7 seasons of winterizing and running it on the muffs while doing it it might pop once or twice. but it seems it has gotten more frequent. I think it is electrical which also could be the cause of it bogging a little sometimes down at higher speeds.

 

[Expidia]

Can anyone locate a mercury oem coil with the info in the pic below?
I figure its 16 years old and it can't last forever.
I'd like to change it first myself and test before I have to finally bring it into a merc shop.

I'd like to buy it off a site thats discount rather than pay retail as the shop would charge me if they did it plus the labor.
Seems easy enough for me to do this myself.
Thx

 

[Expidia]

here is a helpful post I googled that says air/gasket leaks can cause popping and bogging down and to test it spray wd40 around the carb gaskets while the ob is running in water hanging off the trailer or in a water bucket (not on muffs).

http://www.justanswer.com/boat/41jae-making-25-hp-johnson-backfire-exhau.html#re.v/328/