Changed stator & trigger. Now no spark.

1986 Mercury 75hp. It sat for many years and replaces my identical motor that locked up. I've got it running but have some occasional power-drop and electrical issues. I've been gradually replacing everything I can with parts from my old motor that I know are good.


Yesterday I swapped the stator and trigger and flywheel, hoping that was the cause of my electrical issues. Easy job and wiring both back up was uneventful. I followed the wire color guide stamped on the switchbox. While I was in there I swapped some other things, like the starter solenoid, the wiring harness, and the mercury switch. Just replaced every item and wire the same way the old one was.


I felt good because the wires on the old trigger were in horrible shape. Corroded and cracked and burned.


Tried to start it afterward and no spark. Turns over strong but no pop. And my cheap Harbor Freight spark tester showed no spark. It behaves as if the kill switch is thrown (happened to me before) but that is not the case here,


Is there something I have to do after swapping a stator/trigger to, I don't know...sync them up again, or make them work together?


Two odd things stand out: The switchbox says "WHT-BLK" where the bottom-most wire from the trigger hooks up. On the trigger I stripped from my parts motor, that wire is definitely YELLOW and BLACK. The same shade of yellow as the solid yellow wire that is connected above it. And on the trigger I replaced, that wire was solid black. The other thing that I noticed that the switchbox on my parts motor has a black wire coming out of the sealed interior of the switchbox that was grounded. The switchbox on my new motor does not have that wire, but every corner of it is grounded. Both are pictured below.


Sorry this is so long, but hopefully someone has some advice for me. Where to start chasing down this no-spark situation, and could it be related to my stator/trigger swap?

Why didn't you use the box from the parts motor? I wonder about compatability here too.

timguy said:

Why didn't you use the box from the parts motor? I wonder about compatability here too.

Click to expand...

I can easily move over the switchbox. I didn't even think to do that because the two motors are identical right down to the model number. I even had the box from the parts motor off and in my hand, because the stator and trigger wires were routed behind it. But it's not defective, the motor has been running, just suddenly won't start since I swapped out the parts I listed above.

I was wondering if there's something I have to do with the stator or trigger after I installed them to get them working together again. This is my first time with a repair of this size.

Appreciate the response.

They are pretty much "plug n' play". Check closely the wires entering the trigger. Sometimes the conductors can break underneath the insulation. Handling them can cause a break on old components.

I'd check the little mercury switch, don't know if it can be bypassed. Just a guess.

Just a guess like I said, I've not seen one on a motor ( a few laying around at shop) but my understanding is it has mercury in it, it's a tip over switch, don't know if its like a kill switch ?
I'm sure someone with more expertise can answer.

Neat, I have a couple around, usually used with hood and trunk lights. Seems some OMC's used them years back as a neutral safety switch?? Anybody remember? Probably not applicable here, however.

Mercury switch: yes, I've since learned that it's a safety cutoff that kills spark if the motor is tilted up past a certain level or if the motor kicks up suddenly. I remember putting it on...it has a groove that matches a raised bit so you can only install it at the correct angle. Its wire is black/yellow and ties into the kill switch. First chance I get I'm going to disconnect it and see if magically I have spark again.

And leave the silly thing off! About 99.9999% of the outboards out there don't use one. Guess why?

Jeff

*UPDATE*: Today I disconnected the black/yellow (kill circuit) wire from my switch box, and I had spark again. Motor fired right up. I was very relieved since now I know where the problem is and that my stator/trigger/flywheel swap was OK. Now I have to pick the remote control apart and hopefully it's something obvious.

Great, thanks for the report. Strange the short happened while working swapping parts.

Yeah. My guess is it was close to shorting beforehand, and all the jostling and futzing around with the wire harness and cables around the battery finally did it. Whatever the reason I'll track it down and put it behind me ASAP.