Sudden motor shuting off

[Bartman82]

1977 Johnson Seahorse 70 HP. Motor has always ran fine and is very clean. Was getting on plane no problem and as soon as throttle was backed off to half, the motor shout off. It was like turning the ignition off. Now it won't fire at all. Turns over fine but nothing. Would appreciate some troubleshooting advise.

Thanks,
Bart

 

[1946Zephyr]

Re: Sudden motor shuting off

It sounds like ignition troubles to me. I would check for spark.

 

[jonesg]

Re: Sudden motor shuting off

A timing light will show if its sparking, or jump a plug against the block.
Sounds like the ignition died but you won't know til you verify.

Unplug the main harness plug and see if spark returns when you jump the starter solenoid with a bit of wire. I use wire with an alligator clip on one end and touch the other end to the contact.

If spark returns the problem is in the harness, kill switch , kill wire (black/yellow stripe) or ignition switch.
Try that for now.

 

[joey nathan]

Re: Sudden motor shuting off

Right, that neutral interlock is in the remote control isn't it? It may have failed closed and grounded your spark...

 

[Bartman82]

Re: Sudden motor shuting off

A timing light will show if its sparking, or jump a plug against the block.
Sounds like the ignition died but you won't know til you verify.

Unplug the main harness plug and see if spark returns when you jump the starter solenoid with a bit of wire. I use wire with an alligator clip on one end and touch the other end to the contact.

If spark returns the problem is in the harness, kill switch , kill wire (black/yellow stripe) or ignition switch.
Try that for now.

I understand what you are wanting me to do but need verify something. Is the main harness plug the samething as the black/yellow wire going into the power pack? If not, what does it look like and where do I unplug it from?

Thanks for your time!

 

[Bartman82]

Re: Sudden motor shuting off

I followed CDI electronics troubleshooting for no spark. 1)unhooked black/yellow wire from power pack. 2)Disconnected yellow wires from rectifier. 3)checked all connections and grounds. Was going to pull flywheel to visually inspect but don't have a socket big enough. Still have no spark on all 3 cylinders. Is the main harness plug red with about 5 connections mounted on the side of the motor?

 

[Al-53]

Re: Sudden motor shuting off

Yes the big red plug is the connection from the controller to the engine....that was the plug jonesg wanted you to unplug and jump the motor..to see if you had a short in the controller..maybe the neutral switch is gone....or a bad wire in the controller


Al