won't start

[Anonymous-0]

I was reading some of the "worst tractor" posts and some commented how the tractor wouldn't start when hot. We have all been there. That got me to thinking, why won't some engines start when hot? Same compression, same fuel, same spark as it had 2 hours ago when you started it cold. What's the deal?

 

[CalJim]

When I was a kid we had a John Deere that would do that, Uncle Bob always said it was "vapor lock". Something to do with the fuel system, I believe. Need all your advice on this one, please. CalJim

 

[RobMD]

In a diesel engine, that is a sure sign that the pump is going.

In a gasoline engine, the only thing that I can think of based on an ideal engine setup is vapor lock. I think that as gasoline is heated up immensely, it displaces all the air, and it will not fire.

 

[old]

Lots of thing can have to do with that. Coil might be weak so you have weak spark. A small intake leak so you have low vacuum. Vapor lock because the gas line gets hot. Valve gap is just a tad tight so the valves aren't sealing as they should and on and on
Hobby farm

 

[Richard L]

I used to have a JD garden tractor that would do that same thing. My cure was to remove the gas tank cap and while I had someone else turning the key I would put my mouth over the inlet and blow hard. It always started when I did it. Don't be in the front yard doing that when the factories let out.