by lefty » Sun Aug 23, 2020 1:43 pm
I think I've gotten to the bottom of this but need some guidance. How long should it take the autochoke thermostat to fully open the choke?
Currently, the machine needs anywhere from 3-5 minutes to warm up to the point where it has the choke fully open. It's about 90 degrees here right now and the machine is outside. I started it and after about a minute, the arm from the thermostat was still not moved over enough to hold the choke open. So when I put it under load, it vibrates closed and flaps around, which was creating my dropping rpm symptom. If I hold it open with a screw driver, it would run properly.
It appears that when the machine is not under load, the governor is pushing the throttle plate closed, which is holding the choke open. But as it comes under load, the governor pushes on the throttle, releasing pressure on the choke alowing it to close. Without the pressure from the linkage of the thermastat choke, the choke plate flaps around, forcing the RPM down.
After almost 5 minutes, the thermostat had finally warmed up and moved enough to prevent the choke from closing when it came under load.
This is a lot longer than I'm used to seeing. From what I've been able to find, the failure on these seems to result from the choke sticking open, not closed.
I'm thinking of replacing this but I can't find anything on how long the auto choke should take fully warm up and open the choke. Is it normal to have to let these warm up for that long. If so, I guess there's nothing wrong with this and I've been wasting everyone's time. Sorry about that.