Motor will not stop and choke solenoid will not fire

[kb67]

Well, I finally got my 1978 80HP mercury running, now it doesn't want to turn off. At the same time as it had trouble turning off, the choke solenoid will only work when the starter is engaged. When I unplug the wiring harness from the motor I can jumper a positive and negative to the pins on the motor and get the choke to work. I do not see any obvious shorts, but when I check the negative wires on the starter solenoid to ground (anywhere on the motor) I get 0.34V. When I checked my other boat I got 0V with the same check so this seems bad. Does anyone have any ideas or methods to troubleshoot? I did already change my switch.

Thanks.

 

[Chris1956]

A couple of things come to mind. First, maybe the choke button is stuck on, or it is mis-wired. Secondly, when the motor harness is unplugged, the motor will not have any battery power, as the battery cables pass thru the motor harness. Is that what you have, or has it been altered?

 

[kb67]

I don't believe it is the choke button. When I installed the new ignition switch I switched from the old separate choke button to a push to choke to clean up the wiring a bit inside the mercury control box.. I had the same condition before and after the new ignition switch.

Yes, everything runs through the motor harness.

Thanks for any ideas...I think I might be leaning towards the starter, starter solenoid, or maybe the choke solenoid having a short.

 

[Chris1956]

OK, Remember, the choke is powered by the white IGN Power wire, inside the control box. The white wire needs to be hooked up to the choke button. I would assume, your new "Push to choke" keyswitch has this connection internally. The choke button wire is grey, right?

 

[kb67]

Yes, the choke wire is grey. That was the one easy one to get wired up right when I installed the new switch. I cut the extra white wire to the choke button when I installed the new switch.
Thanks.

 

[Chris1956]

Well, It seems like you have the new ign switch wired incorrectly. A 1978 inline 4 cylinder will have ADI Ignition. So you want an ign switch with two "M" terminals. One will get a black wire for ground, the other will get the orange (or salmon) wire to kill the ign. The ign switch will also have a red battery wire("B"), yellow starter solenoid wire ("S"), grey for choke ("C") and an Ign terminal ("I") to run accessories, like tach. That should get the white wire.