1992 90hp 2-stroke Yamaha blows main fuse as soon as battery cables are attached

ebsworj

Petty Officer 2nd Class
Joined
Mar 7, 2005
Messages
173
So i just swapped my trusty old yamaha 90hp 2stroke onto my new to me boat and connected all the cables under the cowling. Then went to hook up battery cables (correctly) and as soon as I touch the last cable to the battery it blows the 20amp fuse under the cowling. I haven't bothered to connect any of the gauges or anything besides the main harness 10 pin connector from the motor to the controls

If the 10 pin is disconnected the fuse dosn't blow is a clue but I'm not sure what it means how how to track down the problem. It ran great last week on the other boat.
Also I tested a bunch of pins in the connector for voltage and 9 of them are hot, at the same time, so that can't be right!!

Got any ideas? Not sure what to try now.
 

ebsworj

Petty Officer 2nd Class
Joined
Mar 7, 2005
Messages
173
Thanks for the reply Robert, I wish it was that simple, I even tested the battery voltage incase it was magically backwards. I wish. The thing I didn't mention is when I was removing the motor from my old boat, I thought the 10 pin main harness connection under the cowling twited apart. So I grabbed it with 2 sets of pliers and twisted. It doesn't twist apart, it pulls apart with a locking ring on it that does twist.

Long story short when I went to put it back together i notices all the pins were bent over and the femaie end too. So I slowing bent the pins and receptical end back to straight so that the connection would fit together again. It does go together now but i wonder if I somehow ruined the connection or it could be shorted inside of it where I can not see?
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Well, I have a C90 and have hooked up battery wrong at least once, blowing that fuse....Sounds like those 10 pin connectors are not compatible...
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
8,851
Thanks for the reply Robert, I wish it was that simple, I even tested the battery voltage incase it was magically backwards. I wish. The thing I didn't mention is when I was removing the motor from my old boat, I thought the 10 pin main harness connection under the cowling twited apart. So I grabbed it with 2 sets of pliers and twisted. It doesn't twist apart, it pulls apart with a locking ring on it that does twist.

Long story short when I went to put it back together i notices all the pins were bent over and the femaie end too. So I slowing bent the pins and receptical end back to straight so that the connection would fit together again. It does go together now but i wonder if I somehow ruined the connection or it could be shorted inside of it where I can not see?

it sounds like you screwed up the connectors and the are shorted out internally, there should not be + power on all of those pins .
Might have to get new harnesses for motor and boat
 
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