First off Dongross, I would like to welcome you to the tractorbynet forum. Glad to have you aboard I know there is a lot of people out there with a general interest in Foton tractors but not much info/knowledge on them.
Second, Please disregard any smart *** comments made about punctuation, grammer, writing styling etc. In my opinion it is very distasteful (especially to a new member) and does not represent our community in the least bit.
I don't own a foton and have only serviced one governor and that was on an old gasser tractor. The governor was a mechanical one hooked up to the main pulley. Mine was just the opposite though it wouldn't idle back down after the governor kicked in. Like Zonta said, mine was full of dust,dirt and grime and the centrifugal armature would slide when the rpms dipped but then snag. I can only guess that if this has a governor it should be mechanical and have some sort of linkage tied to the injector pump to pour more fuel in when the RPM's dip.
CHINESE TRACTOR OWNERS CLUB FORUM - Foton Here's a link for the Chinese Tractor Owners Forum of America. A lot of guys there are running Fotons. Check out the Dong Feng Forum too because I think they are pretty much essentially the same tractor but could be wrong.
By just browsing the linked forum it sounded like some foton owners were having problems with the fuel tank vent and were collapsing the supply line to the injector pump. It might be something worth checking out to see if it revs up faster with the fuel cap off.