Guaranteed didn't start till 1916.
Their 1st visible was made in 1917. The pump pictured has a WET HOSE, [was not made till 1924]. Being you have the castiron base, my guess is ABOUT 1918-1920, [& someone did away with the DRY HOSE VALVE].

Reproduction/Fantasy Cans
http://i124.photobucket.com/albums/p2/oldegaspump/AllCansMASTERTHUMBNAIL_zps4bfdbbc7.jpg
Rnd Can Re-lids