Blown Fuse

[m.woody]

I have a Johnson 1972 85hp outboard motor. After running for a few minutes the 20 amp fuse blows. I have put a new fuse in and in a few minutes it blow again. How do I fix this issue?

 

[Gus-71]

Re: Blown Fuse

Hi!
Welcome to Iboats!
It seems that you have a shortcut. Eather it is the wire or the component it is supplying.
Check wire(s) and component for cracks / damages.
Do you know what the fuse is supplying?
Is i possible to disconnect the wire at the component and se if the fuse is not blowing
Somtimes electrical faults can be hard or very easy to find.
Good luck!

Gus-71

 

[boobie]

Re: Blown Fuse

Best thing to do is find a wiring diagram for the mtr and trace it down. The diagrams will give possible locations where the prob might be.

 

[emdsapmgr]

Re: Blown Fuse

Make sure that the engine is the only thing that is powered by that fuse (a tach is ok.) Sometimes owners connect the radio, lights, horn, etc. direct to the power in the control box. That's just too much load for that fuse.

 

[m.woody]

Re: Blown Fuse

Hi!
Welcome to Iboats!
It seems that you have a shortcut. Eather it is the wire or the component it is supplying.
Check wire(s) and component for cracks / damages.
Do you know what the fuse is supplying?
Is i possible to disconnect the wire at the component and se if the fuse is not blowing
Somtimes electrical faults can be hard or very easy to find.
Good luck!

Gus-71

Thank you Gus,

We disconnected everything except the Motor to the battery on Sunday. And we turned on the switch to the motor and a few minutes later it blow out. It doesn't seem to matter if it is running or not. I can't seem to figure out what is going on.

 

[m.woody]

Re: Blown Fuse

Best thing to do is find a wiring diagram for the mtr and trace it down. The diagrams will give possible locations where the prob might be.

I have the book and the wiring diagram for the Johnson 85 horse power and I still have no idea have to trace it down.

 

[m.woody]

Re: Blown Fuse

Make sure that the engine is the only thing that is powered by that fuse (a tach is ok.) Sometimes owners connect the radio, lights, horn, etc. direct to the power in the control box. That's just too much load for that fuse.

There is nothing else attached to that fuse expect the Motor and the Remote.

 

[seahorse5]

Re: Blown Fuse

Warm up the engine, then turn it off and disconnect both choke wires, and restart and take it for a run. If someone had left the key on for a long time, the one energized choke winding (there are two separate windings) would overheat and cause a short in the system. That motor has an automatic 1/2 whenever the key is turned on and the engine is cold.

 

[emdsapmgr]

Re: Blown Fuse

Check your keyswitch. I've see the key switch short out if it was exposed to rainwater. The key switch is supposed to mount with the drain hole downward. If it is out of position, it can hold water after exposed to rain. That can lead to a short at the switch.