6v 8n weak/intermittent spark

[mleroy1989]

Hello! I posted last year to get my 8N running and you guys were a great help! Over the winter I was able to diagnose and repair a few things that went wrong unfortunately this time I'm looking for a bit more advice!

Quick overview: 8N, 6 volt system with side mount distributor. Tractor has been running fine, now it's only getting a weak and intermittent spark.

Whole story: The tractor ran great (mostly) all winter and kept my driveway plowed and had a fair amount of work hauling firewood out of the woods. Last week I was running the tractor and just before I went to put it away it sounded like it started to miss on one cylinder. The next day I started it up (fired up quickly) but right away sounded like it was missing on one cylinder intermittently. It would miss enough to bog the engine down and not respond to throttle then kind of even out. Choke and throttle setting had no impact on operation.

I'm troubleshooting it now and I'm unable to get the tractor to start.

- I've added fresh gas and ensured the fuel flow from the bottom of the carb was sufficient.
- Battery is on charger now but was reading 6.3 before I came in.
- I've cleaned battery terminals and frame ground.
- Found a few loose wires/corroded terminals and corrected them.
- Initially I tried cleaning the plugs with no luck in starting. I was at the store earlier and bought a new set of AL437 plugs to have on hand and they made no difference.
- Cleaned points and checked that gap was .025. Points don't look pitted at all and all around look new.
- Bypassed the key switch even though I had similar voltage on both sides
- Ensured voltage at coil on both sides
- Removed 2 plugs to check for spark when grounded to the frame. When turning over I'll get 2 or 3 weak sparks then it'll only spark every few turns.

I do know my spark plug wires are a modern automotive style and not the recommended style so that's on my list of things to replace. In the meantime I'm charging the battery and will see if that helps. what else can I look at/test to determine why it has a weak/intermittent spark? If this has been covered in another topic feel free to send me there! I didn't find a thread that seemed to be what I was looking for! Thanks for the help.

 

[JMOR]

Pull rough paper between points to ensure thay are clean enough to make good closed electrical contact. Try another condenser.

 

[Bruce (VA)]

If what JMOR suggested doesn't help, it's time to check the insulator.

Make sure you have voltage across the points, as in past the insulator on the side of the distributor. That is a very common failure point on sidemounts, along w/ the attached copper strip. It's hard to find a short there because it is usually an intermittent . So 'wiggle' the insulator & the copper strip a bit when you are doing your checking. If you find the short there, the Master Parts catalog lists everything you need on page 154. You can make the strip and you could also make the insulators as well. But, somethings are just easier & in the long run cheaper to buy. Get the strip, 12209, screw 350032-S, 12233 bushing & 12234 insulator & just replace it all.
75 Tips

 

[mleroy1989]

Thanks for the replies guys! Cleaning the points didn't help. I did have power coming out the bolt on the side, but the tractor still wouldn't run. I disassembled the distributor and replaced the condenser, points and rotor. While I had it disassembled I filed down the connection points on the copper strip, cleaned the insulators and the screw and reassembled. The tractor seems to be running fine again! This problem was intermittent before but it was more of a minute to minute deal. I've had the tractor running for the past hour or 2 with no problems so far. If the problem returns I'll be replacing the parts you suggested Bruce!

 

[Bruce (VA)]

(quoted from post at 13:07:19 04/02/18) Thanks for the replies guys! Cleaning the points didn't help. I did have power coming out the bolt on the side, but the tractor still wouldn't run. I disassembled the distributor and replaced the condenser, points and rotor. While I had it disassembled I filed down the connection points on the copper strip, cleaned the insulators and the screw and reassembled. The tractor seems to be running fine again! This problem was intermittent before but it was more of a minute to minute deal. I've had the tractor running for the past hour or 2 with no problems so far. If the problem returns I'll be replacing the parts you suggested Bruce!

You're welcome. Glad to help.