Literal Translation
To have a pump hit
Actual Meaning
To feel suddenly tired
Etymology
The expression originated in cycling circles in the 1920s.
But according to Claude Duneton, the pumps in question are the masses of air through which an aeroplane travels and which can cause turbulence due to sudden variations in temperature and pressure. These columns of rising air, which sometimes sucked aircraft upwards, were compared to those caused by the piston of a bicycle pump. This is how the expression came about, adopted by cycling enthusiasts, for whom the pump is of course essential.
We also say ‘un coup de barre’.