JD 790 Pump Tweaks?
 

I have a '99 JD 790 Utility tractor and was told by a half knowledgable farmer the other day he has seen the pump turned up, increasing fuel economy. Does anyone know specifics on how to turn up my pump? I do not have much info the exact pump that was/is stock on it but i can take pics and look for the info if needed. Any help is much appreciated.

Thanks