Vapor Lock in TO-30

The last couple of times I've used my tractor it runs fine for a few minutes. Then it starts sputtering and dying. There is gas being forced out around the cap, which I have never noticed before. I think I need a new gas cap. How many pounds does it take?

Larry

Radiators take caps with pounds. I do not think gas caps are rated by pounds.

Is the gas being forced out around the cap or is it splashing out when really full?

Splashing out is quite normal, but if it's actually being pushed out, that is a sign the fuel is boiling in the tank or fuel line.

Has anything changed? Like the exhaust system repaired or changed? The heat shield above the manifold in place? The fuel line moved, replaced? The timing or carb been adjusted? Fan belt loose? Engine overheating or radiator fins clogged? Heavier than usual engine load?

Any of these things can cause extra heat to transfer to the tank and cause the fuel to boil.

BTW, you don't want to seal the fuel cap. It needs to be able to vent to allow for fuel expansion and allow air to enter as fuel is being used.

I'm having a similar problem - my TO30 is starving for fuel. It acts like I have a vacuum leak but I cannot find it and I am out of ideas at this point.

History -Motor was starving for fuel and dying. Upon inspection, determined I had a blown head gasket. (oil in the water, not the other way around). Removed head, had it reconditioned w valve job at NAPA machine shop - they didn't bring up any problems at all with the head. Replaced head gasket, plugs and rebuilt carburetor. Seems like the tractor is overheating - it will run well when cold, and will idle well as long as I let it sit still, but when I try to put it under a load (PTO/hydraulics) the motor starves and dies. I have sprayed ether everywhere and there are no leaks that I can find from the outside, so I'm pretty certain that there are no problems with the gaskets. The motor oil looks fine, the hydraulic oil is a little milky but this tractor sits out in the weather and occasionally gets water in through the boot on the gearshift.


As mentioned earlier, the motor seems to get extra hot, much more so than when it was running properly. (I kill the motor when I feel it is getting too hot) When looking in top of radiator, it appears that the coolant is circulating okay. I wonder if my passages in the block are blocked. I have cleaned the entire fuel path starting with the gas tank,bowl, etc., through to the carburetor. The float appears to be fine and operating freely from visual inspection when I have it apart, so I don't think the float is sticking.

Once the motor has heated to operating temperature, if I turn the tractor off, I can only get it restarted by holding full choke, and then after a few minutes of that, I cannot get the tractor restarted at all.

I am completely out of ideas except that I may have a cracked head and the heated up /expanded engine is allowing excess air to be sucked into the combustion process and causing a too lean condition. Is there anything else that could be wrong instead of this? Any thoughts on the overheating? I don't have a temperature gauge on the tractor but I have a sense of what is 'too hot' for this little tractor from having used this a number of years.

Thanks for any help you can offer -