1994 mercury 40 hp fuse blown

bateyl

Cadet
Joined
Apr 15, 2010
Messages
12
I have a 40 hp mercury on an 18 ft. bass buggy pontoon. I bought it after been sitting up for several years. I got the motor up and running but evertime I push the ignition switch in to choke it blows the 20 amp fuse on the motor. I have a wiring diagram for the motor but not for the boat under the steering console, and ignition switch. I have disconnected the primer solenoid at the motor and it still blows the fuse. My guess would be a short in the primer control wire from the motor to the ignition switch. Any thoughts or ideas for this problem? Also the wiring under the console had some melted wires that I have replaced.

Thanks
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,590
Re: 1994 mercury 40 hp fuse blown

Could be a defective keyswitch, disconnect the yellow/blk wire from switch and if it still blows the switch is bad..
 

bateyl

Cadet
Joined
Apr 15, 2010
Messages
12
Re: 1994 mercury 40 hp fuse blown

The original switch was broken in pieces when I got the boat. I replaced the switch last week, but one more thing I found out... when the motor is running and you turn the switch off the motor continues to run. I have to use the on/off switch the safety cord attaches to to turn off the engine. Could it be a bad new switch or could the primer or choke wire be switched with one of the magneto wires on the switch. I will check that now.

Thanks
 

bateyl

Cadet
Joined
Apr 15, 2010
Messages
12
Re: 1994 mercury 40 hp fuse blown

There is definitly a difference between a yellow/black wire and a black/yellow wire. When you attach the yellow/black wire to the choke on the ignition switch and the black yellow wire to the magneto on the ignition switch everything works as planned.
When you attach the black/yellow wire to the choke it blows a fuse every time first time.
Thanks for you help jogging my brain.
 
Top