Q.My Manderins are very dry when eating, The tree looks healthy with very green leaves, the tree is around 8′ ft tool and 8′ in di
ameter The fruit is too dry to eat

I would first suspect a water deficit. Water deeply and thoroughly.
But we would need more information on the growing conditions, soil and water management in order to offer better assessment and recommendatons.
Has the fruit always been dry, or is this a recent development?
If always, then it could be in the genetics of the plant and not much you can do about it. But if the fruit used to be moist and has developed the dryness in later years, then it must be related to watering and/or soil fertility.