john deere 125 automatic no fire on left cylinder

[arabbitdog]

have a john deere 125 automatic. have no spark on left side plug. replaced coil, still no spark. swapped coil with right side still no spark on left side, but right side had spark. ground issue? would anyone happen to have an answer or repair manual? any help would be greatly appreciated.

 

[bertsmobile1]

We need to know what engine you have in there
If your coils just have 2 wires on them, spark plug & kill wire then try it without the kill wire connected .
If they that have 3 or 4 wires then things are different and a bit more complicated.
JD make excellent manuals , better than a lot of text books for mower mechanisc, very much worth the asking price.

 

[arabbitdog]

its a 20hp briggs 441577-0113 e1, it has a kill wire and 1 spark plug wire , i did disconnect the kill wire but all that seemed to do it let it run for a couple seconds after turning off the switch.

 

[Fish]

Are you sure that you have no spark, or the engine is not running on one cylinder?
I am not sure that I am following precisely.
An engine will run on only 1 side, if the other side has lost a pushrod or stuck valve.

So are you saying that if you swap coils from side to side, it still only runs on the same cylinder?

 

[StarTech]

Good questions. But is another one "Did you install a known good spark plug in the side that not working?". Plugs do fail too and I have replaced several bad plugs this year.

Also when you disconnect the kil wire was it only at the affected ignition coil? As it sounds like you just disconnected the complete harness or at both coils as fuel solenoid was shutting down.

 

[arabbitdog]

This is my father inlaws john deere. I'm attempting to help him.
Yes regardless of which coil or plugs (brand new,suspected bad or coil from right side)
He has 2 style testers , inline and pen style. we swapped plugs none show spark on left side regardless of coil,plug or which kill wire in disconnected. All show good spark on the right side.
We disconnected both kill wires 1 at a time , no difference. We have to be overlooking something.
THANKS FOR YOUR HELP!

 

[arabbitdog]

Looks like it might be a diode issue for the left side coil? Have to purchase whole wiring assembly. He ordered it and I guess we will see.

 

[StarTech]

Boy this one isn't making much sense; very weird problem.

If it was a diode issue the problem would go away when it is disconnected. You can test for a grounding issue by running a separate grounding wire from the coil's metal frame to another ground point but why would only that cylinder's coil mount be ungrounded.

 

[arabbitdog]

I believe his pen spark tester died before we tested with kill wire disconnected? I couldn't tell it was missing at idle but he said once he started mowing he could tell it was missing. He is gonna mow a few times with the kill wires disconnected until wiring harness arrives. Thanks for all the input