Green’s Dictionary of Slang

1. (US) of a person or a vehicle, to accelerate.

c.1943		‘Bill O. Lading’ You Chirped a Chinful!! n.p.: Pour On Coal: Give it more gas.
1969		D. Pendleton Executioner (1973) 72: You and Horse pour on the coals, get up here as quick as you can.
1978		R. Caron Go-Boy! 32: Pour the coal to it, Sy. Yaahoo!
2000		(con. 1940s–60s) Décharné Straight from the Fridge Dad.

2. to punish severely.

1951

M. Spillane Long Wait (1954) 52: The cops who poured the coal on the residents for parking overtime while anybody with a tag from outside got away with murder.