Mercury 650, was running great, now no spark?!?! Please help...

mjcote

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Jul 21, 2013
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Hello there! I'm new to this forum and have done a lot of reading and learned a whole lot, but can't seem to find exactly what I'm looking for. Hoping someone can help me out.

I have an older Mercury 650 Thunderbolt, 65 hp outboard (I think it's in the 70's). The serial # is 7020523 which doesn't seem to be recognized anywhere. Does anyone know what year this is?

Anyway, the problem I'm having is that the last time I went out, it was running great and then it dropped to about half power (maybe running on 2 cylinders) and was trying to get back to full power but didn't. It's done this before but always managed to fix itself.

I ran a container of Sea Foam cleaner through it and put in new plugs...same thing, ran great for awhile and then back down to half power. The next day when I tried to start it, it wouldn't start.

No spark. No power to the green wire on the CDI box. Is there anyway to jump power to the green wire to test it? The part number on the CDI box is 332-4796. Any other suggestions as to what the problem may be or should I write her a death certificate?
 
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mjcote

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Re: Mercury 650, was running great, now no spark?!?! Please help...

Have now determined that it's a Canadian serial number and it's a 1973.
 

mjcote

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Re: Mercury 650, was running great, now no spark?!?! Please help...

Thanks for the info. Going to try it this weekend. Will post progress.

Can a Digital Multimeter be used for the tests? If yes, what settings do I use? Thanks.
 

CharlieB

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Apr 10, 2007
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Re: Mercury 650, was running great, now no spark?!?! Please help...

Most tests require a DVA meter or a DVA Adaptor to use with any VOM.

You digital is fine but you still need the DVA Adaptor.
 

mjcote

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Re: Mercury 650, was running great, now no spark?!?! Please help...

Thanks so much for all the information.

Finally got some time to go through the Installation and Troubleshooting Guide...with jumper wire from the white/black wire to the black wire and jumper to blue, get spark when touched to ground...so CD module is good.

No voltage between the blue and black wires...thus leading me to believe it's a bad trigger.

So here I sit trying to locate a trigger part #R332-4797.

Just want to make sure my assumption (bad trigger) is correct and that I'm looking for the right one (R332-4797)? Anyone know where to find one (preferably in Ontario, Canada)?

Thanks.
 

CharlieB

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Joined
Apr 10, 2007
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5,617
Re: Mercury 650, was running great, now no spark?!?! Please help...

Most of those triggers are NLA from Merc.

CDI Electronics has a trigger available BUT I think it is only sold as a distributor base assy.

Just for giggles, and since you know your trigger is bad already, cut the wires about an inch from the trigger and test there. It may be possible that the wire(s) have broken somewhere, possibly where they flex. If so perhaps you can replace them. (Fingers crossed).
 
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