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Why won't my cub start?

W

Won'tStart

New User
Had my cub running fine and ready to go before the cold and snow started last week and now it won't start, what is the problem.

When I go to crank the engine over ( hand crank) the carb fill up with gas and starts to pour out and will not get drawn up into the cylinders, i checked the spark plugs and they are dry. If i leave it sit and come back I get a pop type of start and nothinging after that.

what do i do now? is my carb faulty, I pulled it apart adn there is nothing in it, fairly simple set up. Is it the magneto, won't work because of the cold.

help me out here please?
 
Hard to tell form your description of your problem but first check for spark to and through the plugs and you will eliminate your doubts about the mag working. I assume the float is stuck in the carb. or it is sucking air from somewhere. Hope this helps.
 
Are you using the choke? I don't have a cub but I know for my tractors I have to choke, crank till it pops once and then take the choke down to about half and crank till it starts, then run around the tractor and open it up. The mag should work in the cold, at least I have never known that to affect them.
Zach
 
Hold your hand over the throat of the carburetor while a helper makes an attempt to start the engine to see if you have much suction on your hand. Poor suction means low intake manifold vacuum. Could be your intake manifold has a leak. Check the bolts or nuts to see if they're tight. Spray some starter fluid around that area where your intake connects to the engine block while a helper try's to start the engine. If the engine fires you've found the leak. You should do a compression check and compare the readings. Worn cylinders and valves not seating can cause low manifold vacuum. All of this is related. Hal
 
How old is the gas? I was monkeying around with an Oliver 70 a week or so ago that had been sitting for a while. Only way it would start was with starting fluid or if I held my hand over the carb. The float stuck and drained all the gas out. I put fresh gas in and it starts like a dream now.
 
Your float is hung open, or you have some trash in the needle and seat not letting the float close them all the way. Its flooding the engine.
 
Do some diagnostics! Most of us are not mind readers and to say the tractor doesn"t start doesn"t provide much useful info.

Put a paper clip in a spark plug boot and hold it near a good ground and try a start. You should see a FAT, BLUISH-WHITE SPARK, the color of lightning. If you don"t, the problems most likely in the primary ignition circuit.

You obviously have fuel delivery because the carbs loaded wilth fuel-too much fuel. That could occur from excessive cranking trying to get it started, or it could be from a hung float. Rap the carb with a block of wood. That can loosen the float valve.
 
mine is exactly the same way, can you hear the mag impulse "click" when you turn the engine? i have yet to play with the mag on mine, as i need to replace the starter drive before i blame anything else, it kicks out at the first "pop", i can pull the tractor 20 feet in 3rd gear and it will start, also i can hand crank it and hear the mag impulse click so i dont want to do too much until i get the starter working right,i remember my grandfather having trouble like that with a M when it was winter in ill. always had to use the C for chores as it would start, if yours has spark , try pulling it and see if it will run, if it does the mag may need to be cleaned or have new points installed
 
fine dirt/rust in the carburetor would be my guess. The vacuum from the engine can not draw gas thru a plugged jet. It can also hold the float needle from closing. Easy check it to spray some started fluid in the intake screen.
 
Others can correct me if I am wrong, but I didn't have any luck using starting fluid with an oil bath air cleaner. I fixed a way to squirt starting fluid in downstream from the air cleaner.
 
I would say a stuck float or the needle valve not seating in the carb due to debris/rust in it. Also probably plugging the main jet.
 
I would remove all spark plugs then hook the wires to them laying on top of their place. Now with your starter you can turn the engine over and observe the fire also you can place your thumb over the hole to see if it fires on compression. Its a nice way to make sure all plugs are in the correct order and firing on the compression stroke. Your carb should not be dripping gas when turning engine over.
 
Hello WON'TSTART
The only thing between the fuel tank and the combustion chamber is the carb.
If the gas comes out of the carb, the float is not shutting off. That means neddle and seat problem.
When you take the plug out and it is dry, then the carb is plugged up. Squirt a little bit of gas in the carb, and see if the engine tries to fire up. Clean the carb out, and check the float. Shake the float and see if any gas is in it already. Put it in a container of gas and see if it floats. Leave it in there for awhile.
It its got a leak, it will sink. Clean all the float parts, and check the seat as well, and make sure they are free. Float level can be set level with the bowl, as a starting point.
Most of the time its right on that way.
Guido
 
dirt is likely the problem-- but remember he said that this worked until it got cold-- i wonder if he has some water ( now ice) in the carb someplace-- also gas over 30 days old begins to break down -- tho i cant imagine that this would be the issue here- but try fresh gas-- id get the cub into some place warm then you can track all of these things down.-- good luck- i bet its something simple-- tho agravating now that its cold.
 
Sounds like you have my cub. Mine starts great if you run it often. But if it sits for a month or two it is always an ordeal to get it started. I think my engine has low enough comp that it wont suck fuel up very well. If I can get it to hit at all it will start on the next try. Can be very frutstrating.
 
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