spindle has quite a bit of rotation in it before it actually does anything. As has been said, arm off, its dead easy to put it back (unknowingly) in the 'wrong' orientation.
Firstly, take cable and arm off and start van, then turn spindle with a set of molies (carefully so as not to do any damage to it). This *should* see the engine reving 'as it should' just for piece of mind pump is dead.
You then need to mark/orientate spindle so it is 'set' at idle just before moving it any more increases revs. You then need to put arm on so as it pushes straight on and sits against closed throttle stop.
Thats the long winded way.
Easiest/quickest is to undo top nut on spindle, lift off arm so it ONLY JUST clears top of spindle so you dont have to dissasemble the spring assembly etc and turn the spindle a gnats todger and put arm back on. You will know when you have it bang on as it idles right and as soon as you open throttle it picks up asap.
