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1949 8N tractor. 6-volt system. Side mount coil.

When she gets very hot or when she's under a very heavy load, she starts to alternate between racing & idling for about one second each, as if the governer were going haywire. If I don't ease up on her (and, sometimes, even if I do) she then dies and refuses to start again for about 20 minutes. During this dead time, I get a very healthy spark, but no ignition. After 20 minutes, she starts right up & purrs like a kitten.

What's going on and how do I fix it?

- Jim Katen, Oregon

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Depending on your weather it could be vapor lock from the fuel in the carb or tank boiling (tank over engine tractors have issues with this, especially Fords) or, if it's humid and cooler,(mid 60's and cooler) the carb could be icing. The air fuel rushing through the venturi acts like a refrigerant and the venturi is just like an expansion valve in an evaporator. The throat of the carb closes down, the tractor leans out and stalls and 20 minutes later, it's thawed and evaporated. High humidity combined with heavy loads like plowing or deep mowing would create perfect conditions for icing. Small aircraft have carb heaters to prevent this.

Tons of stuff will create the symptoms but the 20 minute restart thing points to boiling or icing. Is your tractor a Robert Frost fan?

If I don't ease up on her (and, sometimes, even if I do) she then dies and refuses to start again for about 20 minutes.

It'll cost you twenty to ensure that I don't send this quote to your wife.

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Hey Jim,

Try twisting the coil in the holder so a different side is exposed to heat. or try insulating the coil case from everything (keep the coil cooler than it is now). I don't think it would be icing, but it is possible. Healthy spark is the wild card.

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Get a mule.

Been there, done that. My neighbors got a mule (Andy, short for androgynous . . .). We made several attempts at getting the damn critter to do useful tasks, including the seemingly simple task of carrying packs on camping trips. In the end, the only thing it was good for was making horrific noises, eating huge quantities of hay, and kicking people -- preferably in the head. And let me tell you, when you've been kicked by a mule, you stay kicked for quite some time.

- Jim Katen, Oregon

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You describe the symptoms of a vapour lock. Hot vapourized fuel inside your fuel lines. Check the routing of your lines re-position them away from any heat source (exhaust pipes) and place a heat shield to protect them from eccess heat. If it is not the lines, then your carb bowl could be boiling as well. Try rubbing a wet water soaked rag over the carb bowl and lines and see if this returns you to service faster. Venting is also a concern, your 60 year old fuel cap may be plugged, creating a lock at the tank. Crack the fuel cap during the next trial run to eliminate it.

If your spark is a healthy blue and the starter turns the engine over its looking like fuel. Clean all filters and vents. Change air/oil and filter.

While we are looking at heat, your coil might finally be breaking down (1949??). It will start to give intermittent spark when it overheats as well. When it retuns to a moderate temp it will work again.

Good luck

1949 8N tractor. 6-volt system. Side mount coil.

When she gets very hot or when she's under a very heavy load, she starts to alternate between racing & idling for about one second each, as if the governer were going haywire. If I don't ease up on her (and, sometimes, even if I do) she then dies and refuses to start again for about 20 minutes. During this dead time, I get a very healthy spark, but no ignition. After 20 minutes, she starts right up & purrs like a kitten.

What's going on and how do I fix it?

- Jim Katen, Oregon

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This reminds me of a funny story. My wife used to have a mid 80s Ford Ranger. Every morning on her way to work, about 20 minutes into her commute, it would stall right in the toll both. She would pay her toll, then two of the toll takers would push her out of the way, and within 2 or 3 minutes it would start right up and she would drive off to work. The carb was whipped, and for some reason when she idled down in the toll both the electric choke would just slam shut and stall it right out. I kept thinking it was vapor lock but it was definately the choke circuit malfunctioning, unplugging it solved the problem and a jumper straight to the battery made for easy cold starts when needed. Easier than convincing her to avoid the toll road.

I know it isn't electric, but I'd make sure the choke is working too.

Tom

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This reminds me of a funny story. My wife used to have a mid 80s Ford Ranger. Every morning on her way to work, about 20 minutes into her commute, it would stall right in the toll both.

My mid-70's Ranger/Mazda Pickup had the hood that hinged at the front. This made it easy to pop the hood, reach out the window and operate the electric fuel pump without stopping. [:)]

I remember doing that, but thankfully have forgotten why I had to. [:)]

What's wrong with Jim's tractor? He said it, "very hot under a heavy load". Old and cranky.

The only fun it ever has is once or twice a year, it gets to act up and listen to all that cussing. [:)]

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This reminds me of a funny story. My wife used to have a mid 80s Ford Ranger. Every morning on her way to work, about 20 minutes into her commute, it would stall right in the toll both. She would pay her toll, then two of the toll takers would push her out of the way, and within 2 or 3 minutes it would start right up and she would drive off to work. Tom

Then suddenly and without warning, the light bulb went on, and they invented the Easy pass lane.

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