Farmall Cub

My 49 will only run for about 3 minutes and then quits. After waiting a few moments it will start and run again for a couple of minutes.
It is obviously a fuel supply problem but I'm not sure where.
If I unscrew the drain on the bottom of the carb fuel runs out for a few seconds and then quits. Shouldn't it continue to run out with the fuel line open? Is this a float problem? It sure makes plowing snow a pain in the CUB.

fuel should continue to come out as the float would open and allow more from the tank. there are a number of possibilities.

first, remove the fuel line from the carb. see if gas comes out steadily from the tank, sediment bowl. if it's sluggish here, you have rust and gunk in the tank, clogging the screen. if it's good here, then you have a carb rebuild to do as the inlet / float needle etc. is contaminated with old gas or crud from the tank. you'll probably find both problems if you have recently acquired this cub.

good luck, and let us know what you find.

In additon to ARTC's suggestions, if the vent hole in the fuel cap gets plugged it will cause the same problem, but that's easy to check. just loosen the cap and see if fuel flows then.

There was one strange thing that happens. When I took off the glass bowl to check that and reinstalled it i watched how it filled up. I noticed it running very slow but if I loosened the bowl retainer nut the fuel flow increased. Would that have to do with the cap vent being blocked?
Also thanks for all the assistance.

If the cap were plugged, it either wouldn't flow there, or would gurgle as the flow stopped to allow air into the tank. The bowl not filling all the way until the tractor is run or the bowl is loosened, is normal, it has to have someplce for the air trapped in it to escape. If fuel flows good with the bowl off, you pprobably have a plug further along, in the fuel system. Is the screen in the top of the bowl clean?

Also this may be a stupid question, but are you sure the cutoff at the bowl is open good? Don't ask why I would think of that.

The screen was clean. I'm going to check the cap tonight when I get home. I had 5" of snow to move last night and stopping and starting did not make it go very quickly.

Steve wrote:There was one strange thing that happens. When I took off the glass bowl to check that and reinstalled it i watched how it filled up. I noticed it running very slow but if I loosened the bowl retainer nut the fuel flow increased. Would that have to do with the cap vent being blocked?
Also thanks for all the assistance.

If you noticed this with all lines connected, It doesn't necessarily indicate a problem. If the bowl gasket is sealing tightly, the fuel can only enter the bowl as fast as it can displace the air in the line. By loosening the bowl, you allow the air to escape quickly and the bowl will fill rapidly.
Try this test with the gas line disconnected at the carb inlet. If the bowl fills quickly and the flow remains full & steady for several seconds, everything upstream should be OK.

I would almost bet that you will find a stuck float and/or seat valve. Tap on the carb with a wooden hammer handle and see if the gas flows faster with the bottom drain plug out. If it dont its time for a good carb cleaning.

I'm going to pull the carb tonight and rebuild. It may or may not fix the problem but it won't hurt to do it anyways. I'm sure it could use it.
I appreciate all the help on this board and the very quick responses.
It really helps when you can get several different opinions about a problem. Here is a summer shot of old 49er
http://photos.yahoo.com/ssweeney01@sbcglobal.net

There is also a screen at the carburetor inlet. It could cause this problem if it isn't clean.

Well didn't get much of a chance last night considering it was -2 below last night here. Suppose to be -5 tonight. I did run it with out the gas cap fully shut. It still quit on me. How come this stuff doesn't happen when it's 80 degrees out.
Just before it quits the govenor starts pulsating, is that due to the imbalance of fuel in the carb?
Plus my starter needs to be rebuilt I've been crank starting it which is fine except getting off and on the tractor is getting real old

Steve,

I feel your pain. Here's my experience yesterday morning when I thought use the loader and clear the ice boulders away from the turn-a-round at the end of my street.

Round 1: 7AM, tried start the Loboy. Tarp had a tear in it, so the carb was encased in ice. Heated some water to melt it and free up the choke and throttle. That worked just fine. Gas cap was frozen in place, used a little water to thaw it out as well. Filled the gas tank and she started right up. Bucket was frozen solid to the ground and up came the back of the tractor. Oh well, I'll wait 'til this afternoon when the sun shines on it and thaws it some. Hopefully.

Round 2: 4PM, tried it again and the bucket popped free. But she only ran for about 3 minutes and died. Checked the obvious, still full of gas and the fuel petcock was open. Started back up and ran for 1 minute, then died. Checked the vent on the gas cap, it's clogged. Switched the cap with my lovely wife's Cub and off we go.

Round 3: Starts losing power climbing the hill, but it runs fine in neutral. Back to the shed, at least it's all down hill. Gas only drips out of the carb when the main jet is removed. Gas only drips out of the fuel line. Gas only drips out of the bowl assy. Yuck, screen is coated with brown slurpee. Clean the screen and gas flows thru the gas line! But not thru the carb. Swiped the carb off my lovely wife's Cub and all is well.

Round 4: A carb rebuild will commence.

Carl


PS: Rudi, there is a Santa Claus. Your wish will come true.

I wish I had one I could swap parts with. I'm just thatnkful the wife said OK to this one. Tonight I'm taking off the carb and bringing it in the house (after I drain all the gas out of it).
This is driving me nuts.It's been snowing here all morning about 2 inches down and a temp of 8.
Last year I was plowing snow, going up the hill to the road when it quit on me half in the road at night! Took me a good 20 minutes before I realized that i was low enough on gas that because of the angle of the drive it starved. Easy fix just add gas! If I had any, had to drag it back down the hill with the truck so I could get out the driveway to get gas. Got the truck stuck half in the road! Oh what a wonderful night that was!

Carl:

Wow! What a day! I seem to remember going through stuff like that, until you and the others helped me fix it. That is the way it goes with older equipment. I am just glad that there is usually an inexpensive fix for it.

Thank you, and yes there seems to be a Santa Claus. Too bad that you had to go through all that! My feelings do go out to you on that one! Sometimes it never rains but it pours!

Will look forward to the present!

Steve, we've all been telling you places to look for dirt, but there is a good possibility that at the temperatures you are running that you have some ice in a fuel line. Does your fuel line possibly have a low place in it where water could accumulate?