850 Tuneup

[Ken Oh]

Since I can't get the carb any better I put a complete tuneup kit in. Ran it for awhile and tweaked the carb. Runs good! Shut it down to check out a charging problem and it won't start. No spark. No spark from the coil. There's 6v going to the coil and my meter shows the points opening and closing. Before I plop down more cash, are there any more tests to the coil I can do to confirm?
Thanks.

 

[xfordownr]

This testing procedure is valid for most automotive coils. Using an ohmmeter, check the resistance between the side terminals of the coil. Do this with all of the wires to the coil disconnected. You should see 0.75 to 0.81 ohm of resistance. Then check the resistance between either side terminal and the center high tension terminal. The reading should be 10,000 to 11,000 ohms. Any significant deviation from these numbers would indicate that the coil is defective.

 

[souNdguy]

Ok.. you have power to the coil primary... pop the distrib cap off, and the dust cover.. now see if you have power to one side of the points with them open... clsoe them.. still got power? points arn't closing good then.

Now.. if you don't show paower to the points with them open or closed, check out the insulator on the distribuitor wher ethe power feeds thru.. the insulators are known to crack and short out there.

soundguy

 

[old]

Take the distributor cap off and double check the points. They may have slipped or got some dirt on them. Then with the distributor cam set so the points are closed turn on the key and open and close them by hand. You should get a spark at the points and from the coil wire also. If you don't then make sure the points are clean. Also has it been wet where you are if so you could have water in the distributor and that will short things out
Hobby farm

 

[Ken Oh]

Points continuity is OK.
Cycling points w/power on does NOT produce a spark at points or coil wire.

Resistance between side terms.= 1.3 ohms
Resistance from side to center terms.= 8.36 K ohms.

Looks like the coil?
If you guys believe it is, would you recommend a Flame thrower or standard coil, since this tractor runs on the rich side anyway?

 

[xfordownr]

You're correct, coil is shot, glad I could help. As to which coil to go with, someone with more knowledge on what works better on our applications will have to help.

 

[old]

Before you go buy a new coil try this. Remove the wire from the coil to the distributor. Now turn on the key and touch that wire on and off fast to that post it came off of. If you get a spark then you may have a bad insulator in the side of the distributor. BTDT and on my 841 it has had a wire going to the points for 20 plus years because that insulator shorted out
Hobby farm

 

[souNdguy]

As old points out.. it does not 100% indicate coil failure. Both of us mentioned the feed thru insulator.

soundguy

 

[Ken Oh]

Thanks to all. Got it fixed. Seems I had a poor conection inside a ring term. on the junction block. It was Olds tip on getting a spark from the dist. wire. There was always 6V there but it wouldn't carry the current.
Runs like a top.
Thanks again.