I started with this problem last year...and still get it a bit.
I'm ok for about 3 and a half mins, then the tears start.
Turned out to be something called 'dry eye syndrome'. Quite common according to my optician. its when your eye lids don't produce enough natural tears due to the pores being blocked. So you eyes are being scratched by dry eyelids, so when your eye does eventually get the tears through, its like a water fall.
I now have some eye drops for racing, and have to clean the edges of the eyelids with a 3pt water 1pt baby shampoo every now and then. Also a 'hot compress' helps too. This is where you soak a flannel with hot water (as hot as you can bear without it burning) and press it against your eye for 10mins every day for a week. This softens the waxy content in your pores and helps the tears get through.
I think mine is down to the paint dust blocking the pores in mine, but not sure what everyone elses is.