1998 70 HP Johnson blowing fuses

[spdracer5]

I have a 1998 70 HP Johnson blowing the main 20 amp fuse with key on. I disconnected the harness with the tan wires at the engine and it stopped blowing fuses. Reconnected and disconnected at tach and it did not blow fuses. All the wires look good. I ordered the manual but would like to troubleshoot it some more before it gets here. Any suggestions.

 

[spdracer5]

Re: 1998 70 HP Johnson blowing fuses

anyone have an idea?

 

[HighTrim]

Re: 1998 70 HP Johnson blowing fuses

You may have a short somewhere in your system.

After retightening the wiring, was it still blowing the fuse?

If so, you will need an analog (needle) type ohmmeter, set at high ohms, connect the leads together momentarily and adjust the meter for full scale.

Remove the fuse from its holder. Attach one lead from the ohm meter into the fuse connector that leads to the engine wiring harness (NOT TO THE POWER SOURCE), and connect the other meter lead to a powerhead ground.

Have the ignition key in the ON position.

The meter should indicate some reading due to the various electronic components BUT it should not read full scale. Should it read full scale, try the meter on low ohms after resetting the meter needle.

Now, start jiggling wires, banging various portions of the engine and boat and watch for that meter to jump to full scale which would reveal the area of the short.