[ACademic]

On a warmed-up engine, you should only have to depress the gas pedal slightly (maybe half way at most) and turn the key (no pumping). Otherwise, you risk flooding it. If that doesn't work, then you might be boiling the fuel out of the bowls. If the starter is cranking the engine slower when warm, that could be a whole different issue (weak ground wires, thermal expansion of an older, non-high torque starter, not enough CCA from the battery, etc.).