48 Cub Just Died Need Help

Cleaning the fuel tank and sediment bowl,
rebuilt and soaked out the carb, replaced the fuel lines, replaced the spark plug wires
replaced the radiator fan belt
and just for grins painted it.

Well it fired up like a champ and ran for 2-3 hrs. It was running fine no missing, power was good no problems at all until the engine just stopped.

It acted like and I thought it had run out of fuel but, no it had half a tank.

I tried restarting and it backfired once and won't seem to fire.

I know little about the magneto and how this thing works (it was my dad's)so what steps do I need to take to start troubleshooting.

I assume I need to check to see if the plugs are firing by grounding them (too wet today) if they don't fire what next? If they do fire what next.

Thanks in advance for any help

Its dark when I go to and home from work but I did pull the plug on the bottom of the carb and had good gas flow to there. That should elminate:

the screen at the top of the sediment bowl (the bowl looks like clean gas, no particulates, and nothing like the rust bowl that it looked like before I started cleaning, I had soaked the screen in carb cleaner just before installing)

and the screen at the elbow on the inlet of the carb.

I did completely disassemble the carb and soak it in cleaner so it should be clean

My next step will be to flood the engine and see if I'v got fuel at the plugs. If yes then I don't have a fuel problem and I'll check for fire at the plugs while I've got them out.

Does anyone know how long a cub will run on just the battery? I did some reading last night on cub won't run problems and did not previously understand how the coil worked that is to say it draws voltage from the battery to fire the plugs. I don't think my alternater works so I recharge the battery before every use. (I only use the cub for 3-4 hrs every year!)

If a dead battery (still turned the engine over) will cause a cub not run I may have found my problem. Battery is charging now.

thanks for all the help

These tractors have run for as long as 68 years with no fuel filter, and the gas these days is far cleaner and purer than it could've ever hoped to be back in the day.

Also you mentioned you cleaned out the gas tank. If you used sand you might have still had some in there and it got into the carb. You can buy in inline fuel filter and install it, pretty simple.

Wild guess: It sounds like a fuel starvation problem as evidenced by the backfire - or pop - which is an indication of a lean condition. Can also indicate timing, although if it ran for perfectly for 2-3 hours, that is doubtful.

mike

Mike G