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sluggish / eratic rpm's

T

trejo77

New member
I have a mercury 2007 50 ELPTO 2 stroke. When I first put in and crank up the motor cranks right up, runs fine, idles fine, and turns around 5600 RPM's. after running the motor for a while it starts acting up. It dosent idle good and dies sometimes when put in gear but the biggest thing is when I crank up and go full throttle sometimes it will go up to normal 5600 rpm's and sometimes it will only go up to around 3500 rpm's. when it only goes to the low rpm's if i leave it at full throttle it will run like that for a while then all of the sudden will take off as if i went from half to full throttle but I havent touched the throttle. sometimes it will do the low rpm thing and just have short spurts of normal for like 1-2 seconds then back to low then again all of the sudden take off. like I said this usually happens after a few hours on the water. I took the boat to the shop in the spring to have the fuel system cleaned and ready for summer so I dont think it is that. Also this dosent seem to me to be a constant miss. Please Help, where should I start?
 
Sounds like you have an issue with a part of the ignition getting hot and not firing a cylinder properly.......or it's as simple as a bad spark plug.
 
faztbullet said:
Likely a CDM module going south....
Click to expand...

Thanks,
Im not sure what a CDM module is but Im going to start with changing all three plugs today and take it out this evening and see if that helps. if it dont I am hoping that a CDM module is what I know as a coil and I am going to switch to a new coil one at a time and hopefully by the time I get to the third one I will have found the problem because i have no idea how to test the coils since it runs fine in the driveway. I am hoping i can just buy one new coil and if i switch one and it dosent fix it i can put the one i switched out back on and move on to the next. please let me know if this is a foolish way of doing it. thanks for your help.
 
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