No power to ignition coil, Please help

[jjlanotte]

Hey guys and gals,

So my mf135 perkins gas wont start. Before it was running for a bit, and then stopping and now nothing at all. I've read through a lot of the forums and ended up changing my distributor cap and my coil. I still get no spark. The engine turns, fuel comes right out of the line, I can smell the gas in the exhaust pipe, but when I put my spark plug tester between my coil and distributor it does not light up. Any suggestions?

 

[jaxs]

" Any suggestions? "
Yup. First off retreive all old ignition parts that have been replaced recently. Using a volt meter or test light,turn key on and;
check from "bat" post on coil to - battery post or bare metal. Do you see voltage? If not,run a jumper wire from + battery post to Bat post on coil then try starting tractor. If tractor starts,post back and we will go from there. If you see voltage,remove dist cap,make sure points are OPEN,hold coil wire 1/4tr inch from metal and repeatedly short across points for half secound with screwdriver. If you see spark from coil wire to metal,clean and gap points. Post back with results.

 

[jjlanotte]

Ill check in the morning. 1 quick question. With the key in the run position, I should have 12v at the +wire going to the +side of the coil yes?

 

[jaxs]

Ill check in the morning. 1 quick question. With the key in the run position, I should have 12v at the +wire going to the +side of the coil yes?

Yes. More accurately,SOME have 12v while others have 6-9v,depending on wherther there is a resistor in line with run circuit. That's a discussion for another day AFTER the tractor is running. The main thing we need is voltage to coil.

 

[Tractor Seabee]

Check your fuses?

Ron

 

[WranglerX]

I usually expect to find 12 volts at positive (+) terminal of coil, if not there I follows wire back to each component on wire (fuse/switch) till I find the 12 volts... The place you looked just before you find the 12 volts is probably where problem is..

One of these can be your new best friend...

Dale

 

[jjlanotte]

==UPDATE==

Ok, so I went out today and turned the key to the on position, no power.I started to trace the wire from the ignition to some sort of box, sorry the name of it is escaping me, and there was a butt connector that I jostled a broken wire out of. I took off the butt connector and when I touched the wire I heard clicks and I had power. I also noticed that from the positive terminal on the Ignition coil it is arcing to the center out. That doesn't seem right to me. Also it is still not starting but I do have power to the + side of the ignition coil.

edit: Its the new coil i bought from yesterday tractors that is currently arcing. I tested it before I put it on and it had 1.4 ohms resistance. The one I took off shows nothing. No continuity no resistance.

 

[jaxs]

==UPDATE==

Ok, so I went out today and turned the key to the on position, no power.I started to trace the wire from the ignition to some sort of box, sorry the name of it is escaping me, and there was a butt connector that I jostled a broken wire out of. I took off the butt connector and when I touched the wire I heard clicks and I had power. I also noticed that from the positive terminal on the Ignition coil it is arcing to the center out. That doesn't seem right to me. Also it is still not starting but I do have power to the + side of the ignition coil.

edit: Its the new coil i bought from yesterday tractors that is currently arcing. I tested it before I put it on and it had 1.4 ohms resistance. The one I took off shows nothing. No continuity no resistance.

What is a center out?

Broken wire inside butt connector(possibly burnt off) plus a bad coil when this began and now possibly another bad coil could be attributed to wire from - coil post to points,points or condenser being shorted to ground. To eliminate confusion,points short to ground every time plugs fire but that's only momentary. If key is left on overnight while points are closed,that's a dead short that can melt wires,points or coil. Now that you have power to coil,try test I suggested bumping points with screwdriver. Before changing anything else,I'd file and check point gap.

 

[jjlanotte]

The plug that goes from the coil to the distributor cap is what I meant. Its arcing from the + side of the coil to the center plug going to the distributor, so about a 1 inch spark. And I do not believe, the wire at least, was melted, it was just a real crappy connection. One of the previous owners put a butt connector right up on a factory plug to the regulator with only a 1/4 of wire coming out of the plug. I'll try your suggestion out in the morning. Crappy thing is my tractor is stuck in the middle of my field and its 90+ degrees out, the conditions are......not ideal lol

 

[jjlanotte]

One more quick question, if this is another bad coil, will any 12v internally resisted coil work from any auto parts store?

 

[jaxs]

Most 12v auto/truck coils before mid 70s will work. Just be sure it's internally resisted or use resistor for same application as coil. New condensers are junk so if you still have old one,switch it in if problems persist. Look for these brands of condensers,Blue Streak,Standard Motors or Echlin. Napa can order if they don't have on hand. There's a spark tester available for $3-$5 (clear plastic bulb with 3" of plug wire attached) that install's between plug wire and spark plug. Easy to see spark and free's up hands not having to hold plug wire while looking for spark,,,,,,and getting shocked.:laughing:

 

[jjlanotte]

To follow up and end this thread, I fixed my issues. The original and second coil I purchased were both indeed bad. After I fixed the electrical/broken wire, I was able to maintain 12v to the + side of the coil. I then replaced it with a pertronix 40611 epoxy filled 3.0 ohm coil. It fired right up. Since then I replaced the distributor cap, all spark wiring, and I installed the pertronix EI. It started up but stumbled around until I loosened the distributor and rotated it to find a better idling and running RPM. I still need some guidance on fine tuning the ignition timing via the distributor. Thank you all for the help.

 

[jaxs]

That's good news. Check with auto parts stores about borrowing a timing light. Thanks for the up-date.