to20 use it to mow runs fine 1hr to 1 1/2 hr then starts to act like a point or condenser problem BUT let sit 1/2 hr runs fine agin
will run with the choke pulled sometimes changed points & cond. any way problem still prissiest

changed temp gage to make sure knot over heating is fine

VAPER LOCK ???
 
You need to learn how to trouble shoot before parts not the other way around
#1 go and run it till the problem starts.
#2 the moment the problem starts check to make sure you have a good blue white spark at the center wire of the distributor cap and at all 4 plug wires, that will jump a 1/4 inch gap or more.
#3 pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in less then 3 minutes.
#4 when was the last time you serviced the air cleaner and dumped the mud and water out and filled with fresh oil
#5 pull the gas cap off carefully and listen for a suction or blow out as you do so. If you have either the gas tank vent is clogged up

Post back when you find for more help
 
Running for 1 1/2 hours is most likely going to be something heat related.

The most common causes are the coil heating up, or as you mentioned, vapor lock.

Like Old said, you need to act quick and catch it in the act. Sometimes heat related problems are difficult to diagnose because by the time you get around to finding it, it has cooled down and corrected itself.

Start with the coil. When it fails, feel the coil. It should be about the same temperature as the rest of the metal in the area. If it is exceptionally hotter, possibly it has the wrong coil. If it's been converted to 12v, the coil would have to been changed or a resistor added.

Vapor lock is caused by gas boiling in the line. It is common on hot days under heavy load. The line should be steel, not copper. Copper is more conductive, can be all it needs to push it over the limit. The line needs to be as far from the exhaust manifold as practical, and as direct and down hill as possible. If it has an inline filter, not only can it be restrictive, but the fuel sitting in the filter can stay there longer, long enough to reach the boiling point. Best to let the sediment bowl and screen do the filtering and have no inline filters.

That tractor never had a heat shield between the engine and the tank, so be sure everything is right to keep the under hood temps down. Air flow is important, not just to keep the engine cool, but the externals also. Watch the radiator for grass, especially when mowing. Be sure the fan is straight and the belt is tight.

Retarded ignition timing causes high exhaust temps. Be sure the centrifugal advance is working, the points are set, the distributor shaft is tight, and the timing is properly set.
 
If it will run that long before it stops
I would think it?s a fuel delivery problem

Could be the vent in the fuel tank stopped up, the fuel will flow for a good while, then as the vacuum in the fuel take increases, the flow of fuel
will stop,

As soon as the tractor stops running, jump off and slowly open the fuel tank cap, if you hear a rush of air into the tank
Then all you do is clean the tank vent hole,
On my TO35 the tank vent is in the fuel tank cap, your tractor may be different,

The fuel tank must be vented properly for the fuel to flow,

As you said if you wait 30 minutes with engine not running the vacuum will slowly be released and the engine will run again

It?s worth a shot!

Another issue is the coil, as it gets hot, if it has a broken wire, it will expand and the wire will break contact, engine dies no spark,

As it cools, the engine will run again,

These are sometimes hard to diagnosis problems,
 
I had a similar issue with my 8n. It turned out to be multiple small issues which combined into one, my stand pipe was partially clogged both top hole and reserve hole, my screen in the sediment bowl was partially plugged, and the small screen in the carb was partially clogged. It would run for a while then die...15 min. later it would run fine...then die. I'd start there...if those items aren't plugged then you can cross me off the list and it's good prev. Mantainence....
 
I had a similar issue with my 8n. It turned out to be multiple small issues which combined into one, my stand pipe was partially clogged both top hole and reserve hole, my screen in the sediment bowl was partially plugged, and the small screen in the carb was partially clogged. It would run for a while then die...15 min. later it would run fine...then die. I'd start there...if those items aren't plugged then you can cross me off the list and it's good prev. Mantainence....
 

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