Farmall Cub

After about a year and a half of sitting, I started my cub tonight. When we rolled it in the shop a few days ago, it wouldn't start. That wasn't surprising considering how long it sat and how old the gas was. So, I pulled the hood off and drained the little bit of gas from the tank and carb. I poured some Marvel Mystery Oil into each spark plug hole and let it sit for a couple of days. Then I checked for compression using the thumb method. I checked the plugs for spark by turning it over with each plug touching the head.

Tonight, I figured I would give it another go. I sat the hood on the tractor, hooked up the fuel line, and put in a small amount of gas. I fired up pretty easily. Occasional puffs of white smoke (Mystery Oil), but otherwise pretty smooth. Good oil pressure.

https://www.youtube.com/watch?v=ETGvbeILIxg

Unfortunately, I was unable to keep it going without leaving the choke rod out. I pulled the main jet and cleaned it with air and a piece of wire. Then, when I tried to start it again, it would fire, but it immediately cut off. I had to come in, so I couldn't tinker with it any more tonight.

I know I need to re-gap the #3 plug because I dropped it when I was checking the compression, and I think it landed on its end. But would that make it quit running after having run pretty well for 5-10 minutes?

A misgapped spark plug would not make the tractor die -just run roughly.

Put a container under the carb and unscrew the plug in the bottom of the carb bowl to make sure you have a good flow of gas.

As Michael suggested, clean the fuel circuit - from tank through to the jet. Make sure both orifices of the jet are clean - the tiny longitudinal one - use a piece of twisted pair/telephone wire which is solid soft copper. It won't damage the orifice. There might be some dirt/crud or even a flake of varnish that is the culprit.

Thanks for the replies. I will go through the fuel system. That makes the most sense.

What would constitute good gas flow? I think this looks adequate, but then again, I have never let gas flow freely from the bottom of my carb.

http://www.youtube.com/watch?v=IE9VnifpR54



I took the carb off to have a look and clean it up. It looked like the idle tube was a little gunky. I'm going to clean it out with carb cleaner and try it again.

Jim:

Yeah, that is good gas flow for sure.

Now take the jet out (hex head to the left of the drain plug on the face of the carb) check the orifices - as mentioned above.

Oh, edit your last post and you will see what I did to embed the video into your post.

Rudi,

Thanks for the pointers. I removed the jet and ran a wire through the orifices again. I also disassembled the carb and gave it a quick cleaning with carb cleaner. Then I blew it out with compressed air before putting it back together. I will try to put it back on tomorrow evening.

For some reason, I am unable to see the embedded youtube videos. I can hear sound, but the video is blank. Of course, that is more of a computer issue than a tractor issue. So far, I'm not a fan of Windows 8.

I am not a fan of Windows 7 never mind 8 I don't even like Vista

Clear your cookies -- both board cookies (see bottom of page for link), clear your history/cookies on your puter. Close your browser and then reopen. That should work. If not run you spyware/malware programs then reboot.

One other thing to consider in the fuel circuit if what you have done doesn't fix the issue, is the needle and cage. BTDT and believe me, it will cause headaches - check for flecks of varnish in the cage under the needle. You will have to hold the cage up to natural light to see the varnish.

Well...four months ago, I reinstalled the carb, and could not get the tractor to fire at all. Since time away from work during the summer is spent at the lake or cutting grass, I really just got around to my attempts to get the cub running again. With assistance from a friend, my attention was turned to the electrical system. There was little to no spark at the plugs. Turns out that 2 teeth were broken off the magneto rotor. I will get a new one ordered and see if that gets the ol' cub running again.

Well .. that would make a little sense. Let us know what you find after you replace the rotor.

The rotor was the problem. My package arrived from TM today. I replaced a leaky carb gasket and my boogered-up carb studs. Then, I put on the new rotor. I checked that each plug had a strong spark, then I put the hood back on. It fired right up. Maybe this will give me the momentum I need to undertake the rest of my overhaul. It's been ugly for way too long.