Dead coil?

[Jim Phillip]

8N front mount, original 6V. Mowed for about an hour and it started running rough, like a couple cylinders only occasionally firing. Checked fuel flow, good. Started it a couple times fiddling with the carb, which is new with about 15 hours on it and no problems. Put the charger on it and noticed the battery was really low, less than half and then when I cranked it I wasn't getting the ammeter jumping showing the points closing. Charged for a few hours and it cranked over faster but still no points or start. Removed coil wire and checked in series between coil and wire end and am only getting 1-2V with the key on. Does this indicate the battery doesn't have enough voltage/amperage for power to the plugs (no spark at the plugs with a plug checker) or is voltage only applied to the coil when its actually cranking? Battery tester says its a little low but good "under load". I've had it die suddenly and it fired right back up after a full battery charge and I suspect I have a bad battery. Or should I go thru the coil, distributor cap, rotor, and points for nth time since I got it running!

 

[old]

8N front mount, original 6V. Mowed for about an hour and it started running rough, like a couple cylinders only occasionally firing. Checked fuel flow, good. Started it a couple times fiddling with the carb, which is new with about 15 hours on it and no problems. Put the charger on it and noticed the battery was really low, less than half and then when I cranked it I wasn't getting the ammeter jumping showing the points closing. Charged for a few hours and it cranked over faster but still no points or start. Removed coil wire and checked in series between coil and wire end and am only getting 1-2V with the key on. Does this indicate the battery doesn't have enough voltage/amperage for power to the plugs (no spark at the plugs with a plug checker) or is voltage only applied to the coil when its actually cranking? Battery tester says its a little low but good "under load". I've had it die suddenly and it fired right back up after a full battery charge and I suspect I have a bad battery. Or should I go thru the coil, distributor cap, rotor, and points for nth time since I got it running!

A full charged 6 volt battery should read 6.3 volts across the top of the battery. Not likely to be the coil but it could be that the points have slipped. Point should be set at 0.015

 

[Jim Phillip]

Nope, I pulled the points this morning and they are working as advertised. I ran a jumper from the ground side of the battery to the coil and it started right up but only runs a few seconds and shuts down. From the schematic, directly powering the coil bypasses the ignition switch, resistor block, and ammeter. Since I am bypassing those parts I am assuming one of them is bad? Not likely the ignition switch since it starts and runs briefly, I jumpered the ammeter yesterday and nothing changed so I am inclined to replace the resistor block?

 

[JMOR]

Nope, I pulled the points this morning and they are working as advertised. I ran a jumper from the ground side of the battery to the coil and it started right up but only runs a few seconds and shuts down. From the schematic, directly powering the coil bypasses the ignition switch, resistor block, and ammeter. Since I am bypassing those parts I am assuming one of them is bad? Not likely the ignition switch since it starts and runs briefly, I jumpered the ammeter yesterday and nothing changed so I am inclined to replace the resistor block?

More likely connections than resistor.. By the way, "I ran a jumper from the ground side of the battery to the coil and..." isn't what you did or it would not have started. What you did was, "I ran a jumper from the negative post of the battery to the coil and..." On your pos gnd tractor, the pos post of the battery is Ground.

 

[Jim Phillip]

More likely connections than resistor.. By the way, "I ran a jumper from the ground side of the battery to the coil and..." isn't what you did or it would not have started. What you did was, "I ran a jumper from the negative post of the battery to the coil and..." On your pos gnd tractor, the pos post of the battery is Ground.

Your correct. I actually ran the jumper from the negative side of the starter solenoid since the connection was easier and closer.

 

[Jim Phillip]

Don't know if it was just the connections or not but switched back to original resistor bloc and it started up. Its running a bit rough but I engaged the 5 ft. brush hog and it powered that. I'll check and make sure I didn't carbon up a plug or 2 and that its getting full fuel flow. Thanks for the help!