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Motor starts skipping when a load is on the boat

M

Mymotorsucks11

New member
Hey I'm nick and I'm new to the forum. I'm hoping y'all can help me out with a problem I have with my motor. I have a mariner 40BE 2 cycle engine no idea what the year is I'm thinking somewhere during the 80's. Here's my problem, I don't know what to call it but I'm calling it a skip in the motor. When there is more than two people on the boat or a lot of gear the motor sounds like it is bogged down and when you accelerate it skips and sounds like it's running off only one cylinder. When I'm by myself on the boat my motor runs better and picks up running on both cylinders only skipping a little before it planes off. To me it sounds like one cylinder is robbing fuel from the other. But I thought it could be the coil pack so I took that out, saw there was a crack in it and tested the voltage and one side didn't was dead so I replaced it hoping my motor would finally work again and to my surprise it still does the same thing. So that lead me to break apart the carb but the carb was so clean it looked brand new. So my question is what else could it be? I hope someone here can figure it out so I can get back on the water! Thanks
 
check the compression...then check and make sure you have fire that will jump 3/8 of and inch with a snap..
 
Not sure which yours has. Older motors use a coil AND a switchbox; newer setups combine the two functions.

Jeff
 
well i just tested the compression and i don't know much about compression but the bottom cylinder was reading around 100 psi and the top cylinder was reading the same thing but we kept pulling the crank cord and inched it up to about 102 psi. So that leads me to believe that the compression is fine not sure let me know what you think
 
Yeah thats what I originally thought cause thats what a mechanic told me and it took me a few months to break down and buy the $180 dollar part and well i just looked at my receipt on the part i bought from mercury and it turns out i did replace the ignition coil so that should be fine now and i think its combined like you said in an earlier post cause with out a picture the best way i can describe it is its like a black box with a orange and black wire coming out of one side that plugs into a positive and a ground or something not sure then the other side has the spark plug caps and hooks up straight to the plugs.
 
[FONT=Calibri, sans-serif] yeah i will try that tomorrow and let y'all know and the complete serial number is [/FONT][FONT=Verdana, Arial, Tahoma, Calibri, Geneva, sans-serif]40BE 676 BS 103387[/FONT]
 
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