Cub starting problems

[zig79]

Please help me figure this out. My Cub has only started 3 times this year. First time I charged the battery and sprayed some starter fluid in it. Fired right up. Second time did the same thing but it died after a couple of minutes. I bought a hand crank for it, turned it one time and it fired up again. Since then it will not turn over. It tries to but won't do it. It has a 6 volt battery and a coil. It took me two days to charge the battery, when I took it off the charger I tried to start it again. Both with the starter and the crank. Nothing. I checked the battery again and the charge was gone. Is it possible the battery is just too weak to get this going? The fan spins, just won't fire up.

[tst]

you can have the battery tested, should not need starter fluid, you need 3 things to make it start, good compression, 90 lbs or more, fuel and a good blue spark

[Jim Becker]

I assume that "Since then it will not turn over." is some misleading slang, as you say the fan spins. It is turning over, just not starting. If it is turning over at something near a normal starting speed, the problem probably isn't the battery.

Have you checked the spark? You could have a weak spark that will only get the engine going with a totally charged battery. If you have a weak (yellow) spark, you need to work that issue. First clean (file) the points. Do not use abrasive paper or cloth. Clean the electrodes in the cap and rotor. Check that your spark plug wires are clean and well seated.

[zig79]

The fan will spend as if it is trying to start. I have a B that when you try the starter, it just hums. I have to use the crank for that to turn over.

[zig79]

Plus, the battery gets drained after just a few attempts at trying to start it.

[Crimson Tim]

So many possibilities at this point... some more history of the tractor would be helpful. You said it only started 3 times this year. What did it do last year? When did it run ok last? What has it done or been exposed to in the meantime?

How old is the battery? The battery dies fast without much cranking. Seems like the battery is done for and/or bad battery cable connections (make them clean no shiny!) and/or worn bushings in the starter allowing internal drag. Where is your ground cable mounted, and is that a clean and shiny connection?
Once you get it running, and it dies out quickly, my first thought would be insufficient fuel. Will it run longer with the choke left on? Will it run better at low idle, but die out when you ask for more RPMs? If so, sounds like fuel line partially plugged someplace or vacuum leak at the carb or manifold gasket. Got any rust in the tank? Doesn’t take much to mess with the carb needle, jet or one of the screens in the fuel line.

Also, 6v requires heavier cables than 12v. If someone put 12v cables on it at some point, it’s going to have trouble delivering enough juice. Does any cable, connection, or component get super hot?

[k hutchins]

You said it had a coil, but didn't say what year your Cub is or whether it has a magneto or distributor.
A magneto creates it own electricity when hand cranking, so if your battery is dead or weak, it has no bearing on whether it will run or not.
With a distributor you need a good battery for it to run because the battery is supplying the electrcity.

The above information will help narrow down the trouble shooting advise. What year, mag or dist.
Otherwise we're all just guessing.

[zig79]

1949 Cub.

[Rick Spivey]

Appears to be a magneto but converted to external coil, the worst of both worlds. So you DO need battery voltage to start this cub; your magneto is no longer acting like a magneto, it is now just a distributor. Your points may need filing and/or setting (0.013" for magneto, even when converted over). Or your coil may have gone bad. You need a good battery to determine the problem from here. See if you have voltage on both sides of the coil; if yes, then it's time to dive into the magneto.

[Waif]

Needs some patience applied.
Cleaning connections.
Checking ignition components.

If that cap was not painted silver , it has had a long life considering the elements effect on it.
Contacts inside it might show burnt crud and corrosion.. Or just too much wear. Same with rotor , points, condenser ect.

[zig79]

The cap is not painted. I installed new plug wires today and cleaned out the inside of the cap. Still won't turn over. I had the battery tested and it was good. Cleaned out the jet in the carb and still will not turn over. It tries to but just will not pop.

[zig79]

I was thinking about replacing the coil or would it be better to go back to the magneto? Amazon sells a magneto coil cover for about $70.

[Don McCombs]

The point that Waif was trying to make is that the distributor cap started life being black and has faded to a light gray. Meaning, that it has been on there a very long time. May be time to think about replacing it.

You only need to be concerned about replacing the coil cap, if you are going back to an internal coil. A new internal coil costs about $65. If the coil magnet bar is missing, that’s another $35. The cost of coil and cap may figure into your decision.

[k hutchins]

I'm a traditionalist so if it were me. I would replace the original coil, points, condensor, and cap.
Then double check the rotor timing to make sure the marks are aligned. Then retime the mag per the owners manual.
If you still get nothing after that l'm lost. It definitely sounds like you're not getting spark, any of the listed componants could be the cause.

[Rick Spivey]

The cap is not painted. I installed new plug wires today and cleaned out the inside of the cap. Still won't turn over. I had the battery tested and it was good. Cleaned out the jet in the carb and still will not turn over. It tries to but just will not pop.

Please don't get mad, I'm just trying to make sure your descriptions are clear to those trying to help. When most of us talk about an engine "turning over", that means the starter is physically turning the engine trying to start it. So when you say "won't turn over" we think either the starter, battery, or wiring is bad, and the engine won't respond to an effort to crank it. It would be clearer if you would describe it as "won't crank", or better yet "won't start". Just a suggestion.....