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1984 Mercury 90hp 6cyl Help

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waterboy76

New member
Just bought this boat/motor, The guy (previous owner) told me it was running perfect and suddenly stop running, he took it to a pro shop and was told the switchbox is bad, they wanted to charge him $800 and say no and put it for sale. I did a compression test and got 150psi in each cyl so i bought it. Now is time to fix it. My first question will be, there are two switchbox, how can i find out which of one is the bad one?
 
Go to CDI and download a troubleshooting manual for engine. It could be a stator or trigger and switchboxes need to be replaced in pairs if one is bad.
 
These switch boxes are very common and available on eBay for about 70 bucks each. That said, it's rare for both of them to die all at once. I suspect the stator went bad instead. This you can check for continuity with a meter: Disconnect the red and blue wires (4 total) from the switch boxes and see what resistance you get to ground.

Use this URL to find the info on your motor:

http://issuu.com/cdielectronics/docs/cdi_troubleshooting_guide_-_2012_1?e=2044661/2001100

Jeff
 
First of all thanks for the few reply, I am a very lucky guy. When I was on my way to start the spark test I notice that gas tank was empty, put 5g of gas and bingo start right away. So problem fix. Previous owner just didnt know what he was doing. I let it run for 10m and ran perfect but notice that the water coming off the pee hole was too hot, I mean really really hot but if I put my hand on the motor is ok, I can keep my hand on motor for 20 seconds and ok but once again water coming off the pee hole is way too hot. Any ideas?
 
First do not buy used switchboxes only new. The reason Mercury says to replace in pairs is if bias circuit is bad in one it can damage the other then when you replace one it damages the new one, vicious cycle.
 
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