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Hi Guys,
I have a 20hp vtwin intek 40g777-0112-e1. the ignition coils are Rotary 31-11578. My problem is that when you touch the kill wire to the block it will not kill the engine. i pulled the
top shroud and touched the kill terminals on both coils with a probe and it killed the engine. I swapped 2 different kill wires and still didn't kill the engine. I tested the harnesses with a meter and they all tested ok. Out of frustration I pulled the coils off another mower and put them on this engine and it works like it should. Do these Rotary coils use a different # kill harness? I feel like I'm missing something simple here. I got this engine to replace a blown engine on one of my mowers but I don't want to swap out until everything works like it's supposed to. I hate to get new coils and it be something simple i've missed. Engine is mounted and being ran in a test stand until I'm ready to swap. Thanks in advance.

Most likely the steering diodes in the harness is installed with anodes being grounded when the cathodes should the ones being grounded. Plus maybe the Rotary already have the steering diodes in them too.

StarTech said:

Most likely the steering diodes in the harness is installed with anodes being grounded when the cathodes should the ones being grounded. Plus maybe the Rotary already have the steering diodes in them too.

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Does that mean I can fabricate a harness without diodes?? Or will that cause the coils to fight with each other.

I would of purchased real Briggs coils. Never have this issue. Sometimes saving money on parts is not really saving money on parts.

I got this motor already complete to repower a mower of mine. Supposed to be an easy swap, LoL. I went ahead and got oem coils and switched them out. Now I know for sure everything is correct. Thanks for the responses.

mackmanj1 said:

I got this motor already complete to repower a mower of mine. Supposed to be an easy swap, LoL. I went ahead and got oem coils and switched them out. Now I know for sure everything is correct. Thanks for the responses.

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So is she a runner?

slomo said:

So is she a runner?

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Is a really good runner. Probably one of the best used engines I've bought. I did the usual fin cleanout and carb cleanout and valve adj before I installed it. Went ahead and put some OE Briggs coils on it didnt feel like fighting that coil issue. No smoke at all, no knocks or rattles either. It was kinda comical when i fired it up on the bench and then I couldn't shut it down properly. How often do you see that.
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