20 amp fuse (start/tilt) wierdness

[Home Cookin']

continuing saga-1987 Johnson 70. The 20 amp fuse (that short little guy in the rubber holder from the solonoid) keeps popping. The line gets noticably hot.
I have found that it pops when I get up to a certain speed (I see it pop by the fuel gauge going off). At first I thought it was popping after a length of time, which explained restarts being OK. I observed that if I went up to top speed soon after starting it popped; if I ran about half speed for 30 minutes it wouldn't. Mechanic idled it for 30 minutes, not problem.

We have replaced the solonoid, fixed a corroded ground bolt, fixed some bad-looking wiruing in the ignition switch. No apparent grounding from a nick in the wire.

Would there be an increase in current through the wire from higher speeds? Shouldn't be, I understand, but anything can happen with old outboards. Or maybe the higher speeds sets off a magic vibration that triggers a short.

 

[Faztbullet]

Re: 20 amp fuse (start/tilt) wierdness

Disconnect the red wire off rectifier terminal and tape back and test. I had a 110 do this that drove me crazy , it ended up being the rectifier even though it tested good. Something was internally wrong with it.

 

[tashasdaddy]

Re: 20 amp fuse (start/tilt) wierdness

also there should be nothing but the motor on that fuse, any other item should not be run off the ignition wiring.

 

[Home Cookin']

Re: 20 amp fuse (start/tilt) wierdness

thanks Fazt-will try that
Tasha's--when you say "nothing but the motor.." the motor continues to run after it pops; what then doesn't work is the started or the PTT, or fuel guage. Doesn't that line feed the wiring block on the starboard side from the solonoid switch/battery connection? Maybe we are talking about different fuses?

 

[McGvr]

Re: 20 amp fuse (start/tilt) wierdness

I'm Thinking Fatz is on to something, The voltage and therefore the Current could be increasing at higher speeds. I'm not sure about the rectifier, but it could be the voltage regulator. If the voltage reg is malfunctioning the Voltage would increase as the RPMs increase.

Ohms law E/R=I E=Voltage R=Resistance & I=current. So if the resistance stays constant and the voltage increases the the current will increase.

The increase in voltage may also be overcoming the resistance of a "dirty Short"

McG

 

[Home Cookin']

Re: 20 amp fuse (start/tilt) wierdness

Back with the same problem despite these fixes:
(note: the work is being done by a good mechanic plus advice from other knowlegable folks)
replaced rectifier
switched out controls with a used set and it worked fine, so we installed another used control box.* The problem seemed fixed--no problem with long runs, high speeds, restarts, etc. The next day I was running it during a storm and it started popping fuses like crazy, and I noticed that I was getting a small shock from the controls.
Went through the controls and found no problem. relaunched in good weather; fuse popped after about 20 minutes at 3/4 speed. Tyhe next day, ran fine at 3/4 speed then I ran it up to full and it popped.
Our only alternative now is to replace the wiring harness--the part is $350. A couple hours labor. But no guaranties.
I'm past the point of no return to walk away from the motor and I feel 9as I ahev all along) that I am this ( ) close to fixnig it....

*Could this have anything to do with it? the controls on this boat are binnacle mount. The motor came from a side mount. The temporary controls were side mount and it worked. But we put a new/used binancle mount on it and the problem returned. I can't imagine why it would matter--but do you all?

 

[Home Cookin']

Re: 20 amp fuse (start/tilt) wierdness

bump

 

[ezeke]

Re: 20 amp fuse (start/tilt) wierdness

Some of the early harnesses had a problem with the black and yellow kill wires at the ignition switch. The solution (SB 1483) was to replace the original insulating sleeve with new shrink tubing.

Symptoms of the problem were shock at the remote control and shorting.

 

[jonesg]

Re: 20 amp fuse (start/tilt) wierdness

When I was getting shocks between the throttle and the steering wheel I used a meter to find the ignition switch was twisting in the bezel and causing a short across the controls.

If your ignition switch is built into the control binacle then that would point at the harness wiring itself.

My ignition switch is seperate.

 

[DJ]

Re: 20 amp fuse (start/tilt) wierdness

Home Cookin,

My thinking was the Rectifier. It has to have a good solid connection (ground) also.

Your getting a shock from the controls is not right. As mentioned, I would be looking at the ignition switch. I asssume the storm you were in was pretty wet too?

I cannot see a need for a wiring harness, they are easy to repair.

I would be looking at the ignition switch.