You are holding the gas pedal way too far down and traveling too fast for the fixed flow rate. Tell your boss to pay you by the hour instead of the mile and the problem will probably go away.
Most machines have a little spray indicator light.
Look for the light. Changes the output quite a bit. Put on a battery charger, but be sure not to hook it up backwards. Definitely recalibrate, though. By using this Web site, you agree to be bound by our usage policies.