Vapor Lock?

[DavidBarkey]

@JSinMO Do you have a low pressure fuel guage you could "tee" in at the carb? That would help solve what is going on . If the flow drops at the carb. so will the pressure. It would need to be a 0-5 lbs guage . A KV. ignion tester would help as well . If the KV's go up when acting up then it is lean . If the Kv's go down You are losing spark or it is rich and with adding fuel helps you know that is not going rich . Other thing that can happen when hot is loosing compression due to lack of clearance at the valves . As the valves heat up use lose clearance . As flat head engine valve seats wear you loose gap . A compression test cold then hot will tell a lot .
Hope this help you find it soon .

[JSinMO]

@JSinMO Do you have a low pressure fuel guage you could "tee" in at the carb? That would help solve what is going on . If the flow drops at the carb. so will the pressure. It would need to be a 0-5 lbs guage . A KV. ignion tester would help as well . If the KV's go up when acting up then it is lean . If the Kv's go down You are losing spark or it is rich and with adding fuel helps you know that is not going rich . Other thing that can happen when hot is loosing compression due to lack of clearance at the valves . As the valves heat up use lose clearance . As flat head engine valve seats wear you loose gap . A compression test cold then hot will tell a lot .
Hope this help you find it soon .

I don’t have a fuel gauge or an ignition tester. It may be time to get them though. I’m sorry im giving short updates, but that’s how im working on it, a little here and there.

I had some time today to mess with it and as soon as it started acting up I pulled the top off the carburetor. The bowl was dry. I checked the fuel pump and it is working I can pull the gas line off of the carb, turn the key on and pump the bowl full close it up, and start the tractor right up. It runs until the bowl is dry again. So my trouble would
seem to be at the carburetor.

I took the top back off and turned the key on and gas was pumping into the carb, but when I put the top back on it’s not making it into the bowl. The needle and seat seem to be ok and I haven’t changed the float at all, but I’m thinking I may need a rebuild kit. I checked all the orifice in the carb body and they seem to open.

It’s not fixed yet but at least I’m narrowing the trouble down.

[DavidBarkey]

Check and make sure the tip has not come off the needle and the fuel passage way in the top of carb is clear. Also check the bowl vent again. If the fuel is coming out of the base when top is off then you have an obstruction in the top or it cant vent .

[JSinMO]

Spent some time this evening fiddling with this again. I ran the tractor again until it died. Took the top off the carburetor and it’s dry.

I took a look at the top of the carburetor and didn’t really see anything out of place.

I took the needle, seat, and float apart nothing to see here, it look good.

I checked the top of the carburetor again, the ports and vent and fuel inlet are clean and open.

I know I’m not getting fuel, and I know the pump and hose are good, the fuel cap is not the problem, I took 1 of the filters out of the line, so what the heck?

I decided to do the obvious wrong thing to get it straight in my mind, and eliminate a vent problem. I left the needle and seat, and float out and put the top back on and turned the key. Now what you are thinking happened did happen. The carburetor filled up and gas poured out through the vent.

I put everything back together and decided to adjust the float. We’ll what do you know, after adjusting it a couple of time it runs great again. I ran it all around, let it sit, started it back up and drove it some more, and no problems!

So did I fix it? I guess so, but this raises questions I don’t have answers to.
Why did this start all of a sudden?
Why did it only seem to happen when hot?
The cross bar on the float is pretty thin, can heat affect the float setting?

As of now we’ll run it and see what happens but so far so good!

[propane1]

Yea, that’s good news.


Noel

[Eugen]

I'm thinking if the pump is fine, it supplies gas to the bowl. Was the bowl dry when you opened up the carb? What if the needle/float get stuck in a shut position when the engine is very hot? The needle usually has a rubber conical tip, maybe it gets stuck in the seat?

[JSinMO]

I'm thinking if the pump is fine, it supplies gas to the bowl. Was the bowl dry when you opened up the carb? What if the needle/float get stuck in a shut position when the engine is very hot? The needle usually has a rubber conical tip, maybe it gets stuck in the seat?

Yes the bowl was dry. And yes the needle is rubber tipped. I did spend some time cleaning the seat. It’s possible the needle was sticking when hot. That explication is as good as anything I can think of.

[Eugen]

That's a clear smoking gun for me. Pump works, bowl dry, means the venturi mechanism of the carburetor used up the gas in the bowl and the float mechanism didn't allow new gas to come in. Either the hinge on the float gets stuck somehow or the needle. In the end it doesn't matter, if it works fine now is all that matters.

Mine behaves like yours, when it gets really really got, the engine wants more choke to keep going, and then it stops. I'll have to take the bowl off just like you and check next time it does it.