1992 Force 120 blowing main fuse on engine

I have a 1992 - 1993 Force 120 outboard. Motor runs great. Just this last weekend, when you give the boat full throttle and run down the lake, it blows the main fuse on the side of the motor. I lost, Tachometer, fuel gauge, volt meter, power trim and the ability to start it. If I put a 25 or 30 amp back in it, turn on the ignition, it blows the fuse.

I brought it home on Friday, filed down the electrical cable / ends where connects to the battery terminals, I filed down the terminals as to create a good clean connection. Put a 30 amp in it, turned the key on...perfect, great volt reading; so I thought it was bad connection, corroded terminals. I went back to the lake on Saturday, tilt worked fine, boat cranked up, idled from the dock, then gave it full throttle to run down the lake, and immediately lost instrument panel, tilt, etc... fuse blew again when giving it full power.

I had some extra fuses, put one in it, turned the key on, blew the few immediately. I had to put tin foil around it to get the boat back on trailer and get motor tilted up.

Boat runs great....just blows that fuse on the side / top of engine. Any suggestions? Is 30 amp too small? Thanks for any feedback.

Kevin.

Re: 1992 Force 120 blowing main fuse on engine

WARNING WARNING WILL ROBINSON!!!

NEVER use foil or put a larger fuse in a circuit. The amperage load of the circuit using the specified wiring has been calculated by a formula so that you do not start a fire, burn up wiring or damage components.

Because your problem is intermittant, and tends to happen when you go to full throttle, I suspect the following.

1. You are getting an overvoltage condition from the regulator. This is easy to check with a volt meter. Because this is intermittant, it may be a regulator going bad.

2. You are getting a direct short to ground maybe by the wiring harness moving or the cables moving against a wire having chafed through.

When you moved the cables around to do the cleaning, you may have moved the suspect wire away from its ground. Later when moving the throttle cables or trigger, the wire again touched ground.

Either of these theories is easy enough to check via visual inspection and voltmeter monitoring.

Check it out and let us know. But by all means, DON'T circumvent any safety device installed on the engine.

John

Re: 1992 Force 120 blowing main fuse on engine

Thanks John. I appreciate the input. Will check out. And tinfoil used as last resort just to get it on the trailer.

Much appreciated.

Kevin.

Re: 1992 Force 120 blowing main fuse on engine

Also, a few last questions...Please. I am no outboard mechanic....Where is the voltage regulator located (what does it look like)? what's the best way to check it? I can't imagine going full throttle down the lake with hood off trying to stick a voltage meter to it!

Any input on helping me get back to trouble free trout fishing....much appreciated.

Kevin.

Re: 1992 Force 120 blowing main fuse on engine

betting on #2

Re: 1992 Force 120 blowing main fuse on engine

Thanks Roscoe. Any suggestions on the correct amperage of fuse? 24A , 30A?

I found a short in the back light for the tachometer. When I move the light from behind the dash, it seems to have a short. Could something that small cause it?

Re: 1992 Force 120 blowing main fuse on engine

The regulator is metal and rectangular and has, in your case, four wires coming from it. Two yellow, one red and one grey. It is usually bolted by two "ears" onto the power head.

You don't have to check for overvoltage under the hood, you can clip your voltmeter accross the battery and it will work as well. You should see a maximum of 15volts at cruise power.

Any short in the wiring can blow the fuse. The reason is that your boat does not have multiple circuits. As far as I can see, the fuse protects everything except the power trim as it has its own circuit breaker.

I question the tach light as it should only be working when you turn the nav lights on. Of course someone could have wired it to be on all the time. If the wire was loose and touched a ground when the boat was at WOT, it would probably blow the fuse.

30 Amp fuses or circuit breakers appear to be pretty standard with the older engines. I think you will be safe with that.

John

Re: 1992 Force 120 blowing main fuse on engine

John:

Thanks so much for the help.

FYI - I loose the trim too. Seems that the fuse on the engine controls, trim, iginition, volt meter, tach, and fuel gauge.

Much appreciated....you've given me a direction to head in when I get back to it.

Kevin.