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Old 29 August 2010, 09:54   #1
jpn
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Merc90 2stroke symtoms for weak/damaged coils ??

What are the symptoms/signs of damage of the ignition coils? I believe my coils fire well whencold but after sustained running they get weak...
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Old 29 August 2010, 13:56   #2
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remove clean and make sure that all earths and electrical connections are clean and tight,
what is your seraial number? you could have the cdm ign system it is a bit more complicated it might be easier for you to get a service manual email me at alan.surman@barrus.co.uk
with a serial number and i will give you the p/n for the correct manual for your engine which you can purchase from any merc/mar dealer
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Old 29 August 2010, 21:22   #3
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Thanks for the reply uncle al....if its a cdm malfuntion meaning it could be the rev limiter kicking in even ifitdoesnt have to??? I was told it was a possibiity?
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Old 30 August 2010, 10:50   #4
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your problem sounds more like either a trigger or stator problem or a bad connection some where
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Old 30 August 2010, 20:47   #5
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I just found out my merc 90 is the CDM type ingition system...could it be one of the CDM that is damaged?
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Old 31 August 2010, 03:07   #6
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yes it could be a cdm
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Old 31 August 2010, 06:33   #7
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thanks for the reply uncle al....all cdm replaced (i borrowed) and still same problem....runs good first 3 minutes...even up to WOT and reaches correct rpms....but misses after 3 min., throttle back to idle for a couple seconds...back to WOT it will be ok for a couple seconds then misses...the longer I let it idle, the longer it can sustain WOT....and the misses...if I just just below 3K rpms all cylinders seem to function alright....

well anyway i will be going to the stator and trigger as you suggested Uncle Al....I know ideally I should try replacing both at same time, but if I had to make a choice, which should I try first...stator or trigger?
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Old 31 August 2010, 10:09   #8
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before you spend lots of money i stongly advice that you do an electrical test of the trigger and stator, if it is a black stator it could be a bobbin in the stator breaking down the new stators are now red more powerfull
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Old 01 September 2010, 07:48   #9
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I am getting really frustrated...the stator is red one....I borrowed stator and trigger from good engine..still the same...good power out of the hole...everything seems normal for a couple minutes, then I loose power...now I will be checking the fuel lines...but the prime bulb seems fine...its hard...I throttle back...idle a couple seconds, give WOT ok again for a short time and I don't even have to pump the bulb...

One thing I noticed, after engine starts to lose power, if I go back to idle for long period, It can sustain WOT longer, as compared to if I just throttle back to idle and back to WOT it will lose power right after it tops out....and the fuel pump is new.....seems like the carbs or at least one carb is not getting enough fuel to get in the bowl...
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Old 01 September 2010, 07:59   #10
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Sounds like a fuel pump problem. Is the new pump sealing well to the block?
Have you tried a different primer bulb?
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