Is it possible your dog is eating elsewhere?
As advised, a hungry dog will eat - they are not 'fussy', that is a human trait put on them by anthropomorphising owners.
The advice about putting his food down and timing it is a good one, if he is hungry he will eat it when it's there, if it not, and he's not eating something else somewhere else, he will be hungry the next time food is there.
Scientists advise that, unlike us, animals think about food when they are hungry, and forget about it when they are not, they are not 'fussy', they are either hungry enough to eat, or not.
All you have to do is educate him into eating regularly, and educate yourself into not worrying about this too much.
He is a dog, he won't go hungry, it's not in his nature.