Key does not kill motor - Honda BF40AY

Eolson3705

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Jul 21, 2011
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I bought a new to me boat that has a 2000 Honda BF40AY in ok condition, but have run into a few problems I am trying to solve. The most major is that the ignition key does not kill the motor when you turn it off. Here are the things that I have tried and tested so far:

Ignition key has continuity across the Mag and Mag Ground when in the off position. No resistance.
When the key is set to On, the Mag and Mag ground are no longer connected internally.
The ground wire from the motor to the ignition key is at .4 ohms resistance. About a 12' cable.
Have reterminated all the connectors at the key.
Have confirmed that the correct wires are pinned on the ignition (black for ground, black/red for Mag)
Ignition starts the boat correctly and remote choke works.
Have hot power on the ignition switch when in the on position to the ignition wire and the battery.
Motor will not stop when you bridge the Mag and Mag Ground directly to each other off the Ignition switch.
Tested resistance across all plug connectors for all wires, no corrosion found. All are waterproof plugs.

I have run out of things that I know to test. Could the CDI unit just be bad for the function of turning off the motor? Is there a ground that is not connected somewhere that I am missing? At the ignition key switch, there is no lead going to the battery directly, only through the remote wiring loom to the motor. As a side note, the emergency kill switch obviously does not work either since it uses the same 2 lead wires to cut emergency power.

Any suggestions would be greatly appreciated.
Thanks
 

alldodge

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Mar 8, 2009
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I would say that if you can run a jumper from the CDI to ground and it still won't die, its either the connector or inside the box
 

Eolson3705

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Jul 21, 2011
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Tried a new ignition switch with no luck. I also ran a ground directly from the starter ground post to the Mag wire with no luck, so not the ground wire path. Not really sure where to run from the CDI directly to ground. Have not torn out all the wire harnesses to get behind the ignition wires to the CDI so not sure if that is where I need to jumper it.
 

alldodge

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Not an outboard guy but since you discussed the two magneto connections on the switch I assumed the BF40AY was a 2 cycle motor. Well just found the owners manual and this motor is a 4 cycle motor, therefore I think you have the wrong switch. The 2 cycle grounds the magneto to stop the motor, a 4 cycle removes 12V to the coil, computer or ignition circuit

https://cdn.powerequipment.honda.com/marine/pdf/manuals/31ZW4607.pdf
 
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