After cranking the engine, carefully check for excessive temperature at the connections of your battery cables. Your cables may be too small and your connections may be less than perfect. Remember, 6 volt systems draw more amperage. All wiring and connections should be as close to perfect as you can get 'em. Is the battery dead? Check it with a voltmeter. Now, a reading of 3 volts for a 6 volt battery is NOT 50% charged! Batteries don't work that way. A 50% charge on a 6 volt battery is 6 volts, and fully-charged is about 6.3 volts. At anything less than 5.5 volts your battery is considered dead-flat and may be too far gone to even accept a charge! For a 12 volt system, 100% is 12.6 volts, 50% is 12.0 volts and dead flat is 10.5 volts!
The battery might be too weak to crank, and fire the engine. Cranking significantly reduces the power available to make good sparks. It is possible to jump-start a 6-volt tractor using a 12 volt battery. Instructions for that are
HERE
Engine turns over but won't start, you smell gas. Did you forget to turn the ignition on? The start pushbutton simply grounds the terminal from the solenoid, so these engines will crank with the ignition turned off. I have occasionally put the key in, turned on the gas, climbed on, put it in neutral, stepped on the clutch, grabbed the choke, hit the start button, and proceeded to flood the engine. For some reason actually TURNING the ignition key ON is not in that sequence. I don't know why, but it has happened enough times that I put it here. If nothing else, you can have a good laugh at my expense.
Won't Start, getting gas & spark - You have spark and gas is getting to the carb, but the tractor won't start. If the tractor has been sitting for some time, it is likely that your gas has gone bad or has water in it. Drain and replace the gas with new. There is a drain plug on the bottom of the carb that will let you drain the entire system and fuel tank into a can. Stick a fresh set of Autolite 437 plugs in it also. If you keep your fuel tank more than half full you should have less problems with bad gas.
Won't Start, water in distributor cap - If you have trouble with your tractor during high-moisture times like, after a good rain, snow, or after power-washing it, check inside the distributor cap for moisture. Dry it all out inside (maybe put a fresh set of points in it) and you should be on your way again. This seems to happen more with the front-distributor engines. Replacing the gaskets on the coil and distributor cap should make the distributor assembly more waterproof.
Won't start, weak or no spark - run a jumper across the ignition switch terminals and try it. If it starts, replace your ignition switch. Don't leave the ignition switch jumpered for long periods with engine off or you could fry the points and the coil. If it wasn't the ignition switch, check for voltage at the small wire on the coil. On a side mount, look very closely at the wire coming from the coil to the distributor. This wire often gets damaged where it passes through the distributor housing. This will cause an intermittent failure that can be very hard to find because almost anything you touch could seem to make it run better for a moment or two. On a front mount, this same problem is often caused by grounded points where the capacitor connects or the coil spring connector on the bottom of the coil is not making good contact with the points (just stretch the springy thingy a little). The front-mount square-can coil is also not a very durable part and some of the replacements seem to fail right out of the box. So, even if you just replaced the coil, you might want to try a different one.
Won't Start, Flooded - Most of these engines require very little choke and are VERY easy to flood. My 8N is very forgiving. Even if I have flooded it, all I have to do is shove the choke lever back in and it starts with a big cloud of black smoke, cough, choke, gasp. Some engines just won't start until you put in a fresh set of plugs. Use Autolite 437 plugs. They run a little hotter and stay cleaner.
STARTS BUT YOU HAVE OTHER PROBLEMS
If your tractor starts, but you still have problems, here are the most common symptoms and solutions.
Runs for about 1-minute and quits; restarts in about 5-minutes = BAD CONDENSER, replace it.
Runs for about 3-minutes and quits; will not restart = GAS TURNED OFF (go ahead and laugh, I've done it, more than once).
Runs for about 5-minutes and quits; restarts in about 10-minutes = CLOGGED FUEL SCREEN. Fuel trickles but won't flow.
Runs for about 15-minutes and quits; restarts after about 30-minutes cooldown = BAD IGNITION SWITCH, jumper across switch to test, and if problem goes away, replace ignition switch.
Runs for about 30-minutes and quits or starts running rough; after 1-hour cool down restarts and runs fine = BAD IGNITION COIL, replace it.
Here is a laundry list of other things to check before you start adjusting the carb:
Tractor is flooded, gas leaking out of carb. Float valve in carb may be stuck (whack side of carb with a wooden hammer or screwdriver handle).
Leaking or cracked manifold,
Broken wires from distributor to engine,
Incorrect firing order (should be 1243 front to back),
Grounded or loose points.
OK, FINALLY! Here is the carb adjustment procedure you came here to get!
