Engine fuse blowing, sometimes

[ConB]

I have a 1987 OMC Johnson 150 hp on my Outrage 18.

The 20 amp fuse that is on the port side of the engine blow twice on start up last fall.

The boat is at home in the driveway and I can not make the fuse blow again.

Two pair of eyes have searched for bare wires and I have tipped, turned and wiggled everything I can touch.

Any ideas from the members is welcome.

Con

[Seahorse]

That fuse feeds 12v through the red wire to the keyswitch which in turn feeds the 12v to the purple wire for gauges, accessories if installed, and power back to the motor when the key is ON. Look closely under the dash at the gauge wiring and connections and for any chafing or rubbing of the harness on the motor.

If the fuse blows only when you turn the key to START, then the problem may be somewhere along the yellow-red wire or inside the control box or starter solenoid.

[ConB]

Thanks Seahorse.

I've been wondering if the problem could be in the key switch itself. If memory serves, big if, the engine did not start on first try and when I reprimed it was when the fuse blew. But I can not make it blow again, yet. Primer solenoid seems to check out OK.

Con

[Seahorse]

You can remove the purple wire from the keyswitch to eliminate the gauges and engine components. If it blows when priming remove purple-white wire and retest. if it still blows fuses there is a keyswitch problem. You said that it did not blow while cranking the motor, that is the yellow-red wire

[jimh]

Re the ignition key switch wiring, be guided by

http://continuouswave.com/whaler/refere ... witch.html

As I recall from Con's installation, getting inside the center console and working on the ignition key switch is going to be a challenge.

[ConB]

Jim, thanks for the link to the wiring info. Finally warm enough to go to the boat and continue the search.

Sure wish I could make the fuse blow again, but I can't.

Wish I could see the wires under the deck without pulling them out of the tunnel.

Wish I had a new E-TEC.

Con

[jimh]

Working inside a small center console requires a small person with long arms and contortionist flexibility. I noted at the Boston Whaler factory that fitting and assembly of center consoles was done before the center console was added to the hull, and the console was position in a special elevated work fixture so a person could stand and work from under the console, working overhead.

Chasing intermittent electrical problems is never fun nor easy. My old c.1992 Evinrude engine had a nasty habit of not cranking over when the ignition key was turned. It would only exhibit this behavior when we were anchored at some island about ten miles offshore, on a weekday, by ourselves, with no other boats in sight.

I never found the precise cause. I ended up buy a new solenoid and carefully cleaning and checking every connection in the circuit. That cured it. I disassembled the old solenoid to see if there were any signs of a problem. It never failed to work. I put it back together and kept it as a spare. I also bought a short piece of 4-AWG wire with ring terminal connectors to use as a jumper across the solenoid contacts so I could manually create the circuit for the starter motor if the solenoid failed to operate. I kept that aboard at all times, but never had to use it.

One aspect to keep in mind: does the problem occur when the engine has been run, then shut off, and allowed to heat-soak? Sometimes electrical circuits stop working when they get very warm.