I have an old 600AJN with a carbureted Ford 425 in it that has many issues, but the most troubling is the stalling after warm up and surging when you step on the dead man pedal to try and stop it from stalling. Many hands have been on this thing before me and I have found the wiring diagram to be utterly useless. There are splices and bypasses everywhere, but despite this, the machine used to run just fine. It has only started the surging recently, and the stalling once warmed up is why I have it out of service now.
Surges then dies ? Or sometimes surges and sometimes dies ? Does it restart after it dies ? Run it till it dies then hit it with bit of carb cleaner and see if it starts. If it does then you got a fuel issue. Most likely vapor lock if it happens after engine is hot. If it doesn't start put a spark checker on a plug wire and see if you got spark. If not maybe the coil or spark control module is getting hot and falling out. Beeing that its surging... ID lean more to a fuel delivery issue. That's where I would start in on it
That's what I was thinking, was trying to avoid rebuilding the carb. When it's cold or warming up, there is no problem really. But after it warms up, you can't restart it till it cools down, then it starts right up like nothing is wrong. The surging is stepping on the dead man pedal after warm up. If you don't "give it gas" after warm up it chokes and dies, if you DO, then it surges until you let off the pedal or it times out, THEN it chokes and dies. I can keep it from dying by continually stepping on the pedal to refresh the timer, but it surges the whole time.
If it runs good cold with choke open I would suspect a fuel delivery issue when warm. Is it a duel fuel or straight gas
Dual fuel, but propane was disabled years ago. Sorry for the slow answer, been a very hectic week.