1985 Johnson 90hp Buzzer alarm problems and now no power to motor or Accessories

Haven't had to request help for some time but this has me totally stuffed.
Have a 1985 90hp Johnson. On last trip out started fine run beautifully. Idled about 200 metres from ramp when the overheat alarm started (continuous buzz which I have read in other threads is temperature ??). Checked for anything around pickup but all ok.Took it for a run at full throttle but still the same. Put it back on the trailer and put it on my to fix list. As it was due for a annual impeller replacement, I put a water pump kit and thermostat kit in. Whist I have the leg and thermostat housing off I stuck a garden house in all orifices and the water went in and out as it should.
Put it all back together and kicked it over for a few seconds to see if it turned. No problem but I left the ignition on by mistake as I went to get the garden hose to start it up which was about 3 minutes. When I got back to the boat the alarm was screaming which makes me think it didn't have a cooling problem but electrical. Turned ignition off went and had lunch came back to give it a run and no power to starter or accessories nothing. Put gauge on battery and fully charged. Pulled control to pieces and the buzzer is burnt out. Removed it but still no power. Played with the red lever on Primer solenoid and tried again and it starts, but I must of turned the lever to off as it ran out off fuel. Turned lever back to where it should be and tried again. Kicked over but before it started lost power again. There is 13v to the bottom of starter solenoid and the little fuse close to it is ok. But again no power to accessories. No clicking at solenoid. Nothing. A faulty solenoid would probably prevent it not engaging the starter but why would there be no power to accessories. The only other thing I should mention is I installed 2 new instruments. A tacho and GPS before my last trip when the alarm started, but I disconnected them to hopefully eliminate them as a problem.

Sorry for the long thread but I'm ripping what little hair I have out.

Any advice would be greatly appreciated.

Your explanation of the damaged horn indicates that the internal circuit of the horn itself shorted out (it happens). Leaving the key in the ON position wouldn't have bothered anything unless one of the engines sensors (pertaining to the warning system) was shorted out, and if that took place, the horn would have been beeping before you left the area.

The intermittent power problem, since you know the 20 ampere voltage to the ignition switch fuse is good, would be contributed to a maladjusted neutral safety switch. Loosen the retaining screws and push it slightly towards the lobe that depresses the switch button... tighten the screws.

The starter solenoid can be easily checked by running a small jumper from the large 12v battery cable solenoid terminal to the small 3/8" nut terminal of the solenoid that engages the solenoid (Not the 3/8" nut ground terminal). That should cause the solenoid and the starter to engage, proving the solenoid to be okay.

Thanks for that joereves. I will give it a go today. Still can't explain why nothing else is working. Radio, bilge pump nav lights etc, that has nothing to do with the ignition.

Gazzzz said:

Thanks for that joereves. I will give it a go today. Still can't explain why nothing else is working. Radio, bilge pump nav lights etc, that has nothing to do with the ignition.

Click to expand...

Double check that 20 ampere power fuse... If 12v is flowing through it, there should be 12v registering at the "B" (battery) terminal of the ignition switch which is the other end of that fused wire.