I did a little investigating on this machine, and after taking the throttle body(carburetor, if you will) off, I found another butterfly below it actually in the governor body. There is a little arm on the butterfly plate that is actuated by vacuum(or pressure), and it was almost broken off. I got some JB Weld and glued it back on. It was wobbling back and forth and getting out of it's little notch and then sticking so it wouldn't actuate the governor control. It runs great now. Thanks for inquiry, and I hope this helps.

i've seen a few of these where the governor spring adjusting spring comes loose inside the cover.
I'm not saying anyone would be adjusting this (other than a yale tech) but if you do turn it too far in the wrong direction it will come unhooked from the mechanism inside it.
They have the wire seal on the adjusting screw & nut that should never be broken or missing during normal use, only a yale qualified tech should EVER adjust this setting.

Most of the time i found this wire missing where someone had been adjusting the engine speed to make the truck go faster.
Not a good thing :o/

Hello,
Have you fixed it? I have the same issue.

Thanks for the reply and input. I'll check this out. steve

Have you looked in the throttle body to se if the butterfly is opening? Could also be a governor problem.