46 B Rebuilt carb quits plowing

vincegsc · Apr 3, 2020

Gentlemen,
My tractor is a 46 B all fuel. I've had it for 25 years. Always, in the past has started and run fine. Any trouble, change plugs, points and condenser. Lately been having trouble fouling plugs. I have used Champion 502 for years.

Finally bought a rebuilt DLTX72. Installed it and new plugs. Started right up, tweak needles a bit. Idles great, crack throttle, no sputter. Plow today. After 20 minutes, losing power, sputter, cough. I tweak the needles a bit. Dies. Magneto is WICO X, rebuilt last August. Fuel flow at the carb (crack the line) seems OK. What do I look for now? Why die after 20 minutes and not want to start?

Mike M · Apr 3, 2020

Check for spark right after it dies. Quitting when hot is a classic sign of a bad condenser and or coil.

Also that carb. is for a model A tractor with a much larger bore and it will likely give you fits with fouling spark plugs from being too rich.

Bob · Apr 3, 2020

(quoted from post at 14:19:27 04/03/20) Gentlemen,
My tractor is a 46 B all fuel. I've had it for 25 years. Always, in the past has started and run fine. Any trouble, change plugs, points and condenser. Lately been having trouble fouling plugs. I have used Champion 502 for years.

Finally bought a rebuilt DLTX72. Installed it and new plugs. Started right up, tweak needles a bit. Idles great, crack throttle, no sputter. Plow today. After 20 minutes, losing power, sputter, cough. I tweak the needles a bit. Dies. Magneto is WICO X, rebuilt last August. Fuel flow at the carb (crack the line) seems OK. What do I look for now? Why die after 20 minutes and not want to start?

"Magneto is WICO X, rebuilt last August."

Doesn't matter if the mag was rebuilt last August or last week, have you verified that it's throwing a good, hot spark NOW?

That's the FIRST thing I'd check, followed by opening the carb bowl drain and verifying the bowl has a good quantity of gas in it, and once that drains out flow will drop to what can pass through the needle and seat, needs to be enough to fuel the engine, obviously. Dunno WHY you checked at the gas line instead of the bowl drain, that leaves some things out of the equation.

Actually, I guess I'd do the bowl drain thing first.

Be careful, be prepared to catch the draining gas in a suitable container, and don't immolate yourself or the tractor!

vincegsc · Apr 3, 2020

Thank you, Mike. I heard that about the carb. As I said, I've had that tractor for 25 years, WITH a DLTX72 carb on it. Has been reliable in the past. I suppose someone could have changed it out before I got it.

James Howell · Apr 3, 2020

"[b:654c4848f0][i:654c4848f0]classic sign of a bad condenser and or coil[/i:654c4848f0][/b:654c4848f0]"

Agree.

Steve@Advance · Apr 3, 2020

Be sure the gas tank vent is clear.

kevinstuff · Apr 3, 2020

Don't have a B , my experience is to adjust main jet when its under a load
when its adjusted with no load , it will run too lean and hot under a load , so turn that main jet out a 1/4 turn at time
the color of your plugs will indicate what's going on.

vincegsc · Apr 3, 2020

Catching gas in container, under carb drain, shows 1 cup of gas drains in a minute. That should be plenty to keep it idling. I tried a test light in line with the spark plug. It shows a spark, but that's always a judgement. Is this hot enough spark? I cracked the inlet pipe loose from the carb, in case there was an obstruction choking air. Now tractor starts, and dies right away. Plan points and condenser next.

vincegsc · Apr 8, 2020

(quoted from post at 15:17:16 04/03/20) "[b:21b307aa15][i:21b307aa15]classic sign of a bad condenser and or coil[/i:21b307aa15][/b:21b307aa15]"

Agree.

Whoever said coil or condenser, get your gold star. Turned out to be coil. I had measured primary and secondary resistances to be about what they should. Doesn't matter. Poor spark. New coil will jump a spark 5/8 inch.

46 B Rebuilt carb quits plowing

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James Howell

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