Ariens Fairway spark problems

[Vilfred95]

Hey everyone

I just got an old riding lawn mower that I’m trying to get running again, it’s a Ariens Fairway model 912009, I believe it’s from 1976.

Im having trouble getting a spark, spark plug is fine and I have tested the coil and condenser with a multimeter the best I could. So my question is, have anybody seen a coil like this and know where to buy one?

 

[Rivets]

This is what you are looking for, https://www.partstree.com/models/mg-610689a-tecumseh-magneto/magneto-0/. I must warn you that working on these Tecumseh engines is not for the average DIY guy. Please read the section of this manual, on ignition systems, before attempting any repairs or you could get some where you don’t want to be. https://www.mymowerparts.com/pdf/Te...P-4-CYCLE-L-HEAD-FLAT-HEAD-ENGINES-692509.pdf. 95% of todays small engine mechanics have no idea how to time these engines, once they have taken the ignition system apart. You’ll have to find an experienced mechanic over 50 years old, who has experience with these old engines. Sorry for this answer, but I must prepare you for what you are getting into. If you have more questions before you start please feel to ask.

 

[Vilfred95]

Thanks for the very detailed reply!
I had the ignition system off, to try and measure a bit on it, I can still very clearly see the marks from the bolts so I can reposition it again, is that sufficient for the timing or did I screw that up?
And do you think it will be sufficient to only replace the magneto, I measured 7.33 resistance on 20k with my multimeter on the coils, does that sound about right?

 

[Rivets]

How good a gambler are you? Once you remove the magneto assembly it is a crap shoot if you get it back correctly. I’ve always taught that measuring primary and secondary resistance on Tecumseh coils should be between 0-15 Ohms on the primary and 0-15,000 Ohms secondary. When measuring resistance you must have all three leads disconnected from the engine. Some techs don’t take the time to have all leads loose during testing, resulting in false results. Just my opinion, read my signature.

 

[Vilfred95]

Well, it’s either that or it’s going to the eternal grass fields…
So do you have any tips and trick for removing the old and installing a new magneto? And again, thanks for all the help

 

[Rivets]

Patience is your friend. Not very hard until you get to the timing. Reassemble the parts into the magneto first, install the assembly as close as you think you can, making sure wires will not catch on anything, set the point gap, I use .018”, install flywheel figure tight to set for spark with plug removed. You should be able to spin by hand, just make sure you watch your fingers. Can tell the times I’ve pinched them while testing. If you have spark, torque flywheel and test run. If it doesn’t run or runs rough, timing is to far off and you can go back to trying to move the assembly a fraction one way or the other. Good Luck in your endeavors.

 

[slomo]

Remove all ignition parts. Remove all corrosion from them. Polish said parts to clean metal. Polish mounting surfaces on the engine block. Clean all mounting screws to bare metal. Reinstall parts and test for spark.

Oil that thirst looking white wick that lubes the ignition points lobe.

 

[Rivets]

Slomo, I don’t know how many Tecumseh engines, with internal magnetos, you have worked on, but if the OP follows your instructions his chances of success will go way down. When was the last time you’ve worked on one of these engines, if ever. If he does all the cleaning you suggest, he’ll remove any of the bolt marks he’ll need to set the timing, because he doesn’t have the tools needed to time the engine. Second, it sounds like he is going to replace parts, so why go through all that cleaning. Finally the cam wick should be lubed with cam lube, which is a waxy grease, not oil.

 

[VRR.DYNDNS>BIZ]

Patience is your friend. Not very hard until you get to the timing. Reassemble the parts into the magneto first, install the assembly as close as you think you can, making sure wires will not catch on anything, set the point gap, I use .018”, install flywheel figure tight to set for spark with plug removed. You should be able to spin by hand, just make sure you watch your fingers. Can tell the times I’ve pinched them while testing. If you have spark, torque flywheel and test run. If it doesn’t run or runs rough, timing is to far off and you can go back to trying to move the assembly a fraction one way or the other. Good Luck in your endeavors.

Timing is done with an offset dial indicator to piston .080" but I cannot remember if before or after TDC. Can be done with head off and normal vernier since I am probably one of 10,000 shops that still has the special tool to stick in plug hole with ofset shoe to measure pistoon position. Points should just open at the setting by ohm meter reading. I expect the manual can be down loaded on my site at http://vrr.dyndns.biz/Docs/Repair/linecard.html
The coil is a separate slide on part to the iron lamination on most.

 

[Rivets]

I’ve got the other dial indicator. Always BTDC, but there are different measurements for different engines. Measurements are in the manual I posted.