Cub won't idle up and stalls

[Lpeer21]

New member here, just got the front blade put on my cub and was playing around with it and it stalled out about a half hour into running it, when it would fire up it would idle low then stall back out after about 10 seconds. Went ahead and rebuilt the extra carb I have (robbed from my other cub that's torn down) and exact same issue. Pulled the plugs and cleaned them, put fresh oil in the filter bowl and no changes. Not sure what to check next, I drained the fuel tank and sediment bowl and need to get a new fuel filter, seems like a fuel issue to me, any ideas? Thanks for any info

[Eugene]

Ignition coil, faulty. Typical indicated fault.

Welcome.

[Barnyard]

No gas filter needed. That is what the sediment bowl is for. An inline filter will restrict your fuel flow. Try that before getting a coil.

[staninlowerAL]

Welcome to the forum. When you said "rebuilt the other carb" what did you do?

[Eugene]

No gas filter needed. That is what the sediment bowl is for. An inline filter will restrict your fuel flow. Try that before getting a coil.

Use gravity flow inline fuel filter.

Try what the others suggested. Then replace the ignition coil.

it stalled out about a half hour into running it, when it would fire up it would idle low then stall back out after about 10 seconds.

[Lpeer21]

Welcome to the forum. When you said "rebuilt the other carb" what did you do?

I installed this kit in the spare carb I had
https://farmtractorrepair.com/collectio ... it-for-cub

[Lpeer21]

Appreciate all the answers I'll see how it runs with no inline filter and fresh gas and get a coil if need be

[Clemsonfor]

If you have two cubs even if one isn't running if they have the same ignition type swap parts (coil) from the one that the carb came off off that disassembled.

[cdahl383]

I know on my old Nova when it would act up like that it was usually ignition related. Some ignition component is getting hot and cutting out. Typically it's a coil, ignition module, etc.

Does it just shut off like you hit the ignition switch? Or does it sort of stumble and run rough before dying? Could also be a fuel flow issue. You could pull the line off the carb and turn the petcock on to ensure the fuel is flowing well (make sure to route the line into a bucket or something though or you'll make a mess).

I've also had issues with carbs on dirtbikes where even after a fresh rebuild, the needle would get hung up in the seat and not allow enough fuel to flow in. The bike would start and idle for a bit, but when I gave it throttle it would die out. Took the carb apart and found the issue was a sticky needle (and it was brand new!). I sprayed some carb clean through it and then ran some fuel through it (was on a 2 stroke so there was some oil mixed in too to lube it). Put it back together and then it was fine.

Hope you figure it out soon!

[Lpeer21]

I know on my old Nova when it would act up like that it was usually ignition related. Some ignition component is getting hot and cutting out. Typically it's a coil, ignition module, etc.

Does it just shut off like you hit the ignition switch? Or does it sort of stumble and run rough before dying? Could also be a fuel flow issue. You could pull the line off the carb and turn the petcock on to ensure the fuel is flowing well (make sure to route the line into a bucket or something though or you'll make a mess).

I've also had issues with carbs on dirtbikes where even after a fresh rebuild, the needle would get hung up in the seat and not allow enough fuel to flow in. The bike would start and idle for a bit, but when I gave it throttle it would die out. Took the carb apart and found the issue was a sticky needle (and it was brand new!). I sprayed some carb clean through it and then ran some fuel through it (was on a 2 stroke so there was some oil mixed in too to lube it). Put it back together and then it was fine.

Hope you figure it out soon!

I want to say it stumbled right before it died, I'm planning on picking up a new coil this weekend to try that, had good flow through the inline filter and at the carb

[Glen]

Hi,
You didn't say what year the Cub is, or if it has a magneto or a Battery Ignition unit.
Or if the Cub is 6 or 12 volts.
Cubs made before mid 1964 are originally 6 volts, positive ground.
Some older Cubs have been changed to 12 volts.
The magneto originally uses a special coil, under the cover on top of it.
Below is a listing for it at TM Tractor Parts, you can look at the pics. There is a pic of a magneto there also.
http://www.tmtractor.com/new/el/713fp.htm

The Battery Ignition unit uses a more modern cylinder shaped coil, visible on the outside of it.
The older Battery Ignition unit coils are a smaller diameter than modern coils, and have wire connections at both ends.
If you put on a new coil, you would need a coil bracket that fits the new coil.
Below are listings at TM Tractor Parts, you can look at the pics.
http://www.tmtractor.com/new/el/788fp.htm

http://www.tmtractor.com/new/el/808fp.htm

http://www.tmtractor.com/new/el/693fp.htm

Below is a pic from TM Tractor Parts of a Battery Ignition unit, the coil isn't there in the pic, it goes on top of the unit.

[Lpeer21]

Not sure on the year never looked it up, this one is 12v my other one is a '52 6 volt. I put a new coil on it and new wires and it still wouldn't rev up until I bumped the hydraulics then it jumped to full throttle, now it's leaking hydraulic fluid and leaking coolant out of the cap and smoking like crazy out of the oil dipstick, I'm stumped now not sure what happened

[Mac AR]

Not sure on the year never looked it up, this one is 12v my other one is a '52 6 volt. I put a new coil on it and new wires and it still wouldn't rev up until I bumped the hydraulics then it jumped to full throttle, now it's leaking hydraulic fluid and leaking coolant out of the cap and smoking like crazy out of the oil dipstick, I'm stumped now not sure what happened

Sounds like there are several things going on here.

1. By your description, it sounds like the hydraulics were "jammed" and dragging the engine down, and you managed to make the relief valve open, thereby letting the engine come back up to speed. This is probably why the machine died in the first place, and had nothing to do with replacing the coil and wires.

2. Coolant coming out the cap could be either a bad seal on the cap, stopped up overflow tube, an over-full radiator, or combination thereof. Again, not related to anything you did. Likely a new issue that you need to address. Check the coolant level; it should just cover the tubes in the radiator. Any more and it'll blow coolant out the overflow when hot. But if the overflow is stopped up, the only place it can go is out the cap.

3. The blow-by out the dipstick could be a number of things. Check the oil first; if it's over-full, there's a good chance that the jammed hydraulics have caused the pump to leak, which will fill the crankcase with hydraulic oil. If that's the case, then you're in for a pump rebuild. There's also the possibility that it blew the head gasket and is now putting water in the oil. If you think that's the case, crack the drain plug slowly and see if any water comes out before the oil does. If it's not over the mark, then I would suspect a stuck valve or ring causing blow-by; however, a little blow-by seems to be the nature of the beast since my old 51 smokes out the crank breather and seems to do just fine.

You might check all the things I mentioned and report back, the experts here can likely get you going again.

Mac

[Lpeer21]

Not sure on the year never looked it up, this one is 12v my other one is a '52 6 volt. I put a new coil on it and new wires and it still wouldn't rev up until I bumped the hydraulics then it jumped to full throttle, now it's leaking hydraulic fluid and leaking coolant out of the cap and smoking like crazy out of the oil dipstick, I'm stumped now not sure what happened

Sounds like there are several things going on here.

1. By your description, it sounds like the hydraulics were "jammed" and dragging the engine down, and you managed to make the relief valve open, thereby letting the engine come back up to speed. This is probably why the machine died in the first place, and had nothing to do with replacing the coil and wires.

2. Coolant coming out the cap could be either a bad seal on the cap, stopped up overflow tube, an over-full radiator, or combination thereof. Again, not related to anything you did. Likely a new issue that you need to address. Check the coolant level; it should just cover the tubes in the radiator. Any more and it'll blow coolant out the overflow when hot. But if the overflow is stopped up, the only place it can go is out the cap.

3. The blow-by out the dipstick could be a number of things. Check the oil first; if it's over-full, there's a good chance that the jammed hydraulics have caused the pump to leak, which will fill the crankcase with hydraulic oil. If that's the case, then you're in for a pump rebuild. There's also the possibility that it blew the head gasket and is now putting water in the oil. If you think that's the case, crack the drain plug slowly and see if any water comes out before the oil does. If it's not over the mark, then I would suspect a stuck valve or ring causing blow-by; however, a little blow-by seems to be the nature of the beast since my old 51 smokes out the crank breather and seems to do just fine.

You might check all the things I mentioned and report back, the experts here can likely get you going again.

Mac

Appreciate the info, for the hydraulics a co worker said the same thing you did, its always smoked a little bit but it seemed excessive this time, oil level is normal, I topped off the coolant after putting the coil on and that's when it started coming out of the cap. It's probably going to sit for a bit since our work got cut way down so all my play money to work on stuff is on hold, thanks for your help I'll update if I get anything figured out

[Mac AR]

I topped off the coolant after putting the coil on and that's when it started coming out of the cap.

Aha! If your Cub is anything like mine (and the rest of them), they'll push water out when they get warmed up with full radiator. Once they find their "happy place" they're fine. Mine likes to run just about level with the top of the water neck; any fuller and it's coming out the overflow. First time it did that, I went and re-soldered the overflow tube back onto the filler neck; a face full of hot antifreeze isn't fun!

Hopefully you'll get your other issues cleared up soon, too.

Mac