- I didn't eat until he had eaten his meal .

[abo.omar]

1- I won't eat until he has eaten his meal .
2- I didn't eat until he had eaten his meal .
3- I didn't eat until he ate his meal .
I can understand number one very well.
Is number 3 correct?
If so what is the difference between number 2 and 3?

 

[Barque]

Number 1 refers to what you will or will not do in the future.

Numbers 2 and 3 refer to completed actions.

Number 2 doesn't sound correct to me.

None of the three sentences are natural by the way. "Ate his meal" sounds a little off.

Sentence 1.
I won't eat until he does.
I won't eat until he has/he finishes his meal.

Sentence 3.
I didn't eat until he finished his meal.
I didn't eat until he had his meal.

 

[abo.omar]

Does it mean 'till' or 'unti'l can be followed by past simple not only pat perfect?

 

[Barque]

Does it mean 'till' or 'unti'l can be followed by past simple

Yes, it can.