Electrical issue 2001 125HP Mercury ELPTO (2+2) 2stroke

[mdjorg]

Motor runs awesome but it randomly blows the 25A main fuse after I shut it off. I haven't been able to determine how long after I shut the motor off that this happens. When this event happens there is an excessive active draw off the battery. When I put a new fuse in the new fuse will at times immediately blow the second it is seated into the harness. OKAY... disconnected the main wiring harness on the motor to determine if problem is on motor or elsewhere in boat. Problem remains when main harness is disconnected therefore determine issue to be on the motor. Long story short and many tests later I replace the volt-reg/rectifer, stator, control module (ign switch) and battery. After these "repairs" I still randomly experience the fuse blowing in the same manner as described above. SO... the last time this happened to me I removed the plastic flywheel cover and manually turned the flywheel/eng crank about a quarter turn and the active draw disappeared. IN CONCLUSION what could be causing this? Obviously a dead short or closed circuit someplace when there should not be. Solenoid? Trigger? Wiring harness dead short not obvious to the naked eye? I have retested the volt-reg/rectifier, stator & control mod and all tested good. (even the old ones tested good - I simply assumed one had an intermittent fault that I would never track down) Love iBoats! Thanks in advance for the feedback! MJ

 

[tommarvin]

Its a wire, or the wire in the connector is broken, pull all connectors on the end of wires hard.
It sounds like a short, and you think its on the motor check every inch of wire on the motor first, easy for me to say sitting here.
Do a continuity test on each wire in the wiring harness wires, connect a wire to one end of each wire so the multimeter will reach both wire.
Ok, lets start from the beginning, are you sure the battery(s) are hooked up right please verify, Starter solenoid hooked up right, please be sure, starter connected correctly, to blow a 25 amp fuse it has to be big, make sure everything is hooked up correctly.
If your boating season is over like ours you have months to check everything.

 

[mdjorg]

Yes Sir battery and solenoid are all hooked up properly. The electrical testing I have done leads me to believe the dead short is on the motor and not elsewhere in the boat. It certainly would not hurt to do another deep dive inspection of the wiring on the motor. I did find it very interesting that the last time this event happened, manually changing the crank position made the problem go away. When the issue occurs again I will see if this manipulation of the crank position yields the same result. Until then I won't assume anything. Thank you for the feedback. The additional insight is welcome!

 

[tommarvin]

Its the stator, maybe the trigger if you have it, im not that good with other motors. you need to pull the flywheel and test the stator and trigger, you cant see anything with the flywheel in the way, like you said look for burned wires and burned areas on stator,remove stator and look underneath.
youtube and cdi electronics.com for testing ignition parts.

 

[Fed]

Try & find a circuit diagram for the motor, out of interest I had a look at some other Mercury diagrams & they don't seem to vary much.

Typically the wire runs from the fuse to the harness plug and sometimes loops to a cowl mounted tilt switch.

Unplugging the harness eliminates everything after it but NOT the plug itself on the engine side. Check it for shorts (should be red/purple).

The tilt switch should be normally open BUT it may still be short circuited inside the switch (a common fault).

Finding the correct circuit diagram for the motor is preferred as it will save you time & money.

This was a complete waste unless you found other problems not related to the fuse.

Long story short and many tests later I replace the volt-reg/rectifer, stator, control module (ign switch) and battery.