Got one of our injection pumps under applying by alot! We have cleaned the pump, replaced the Orings,Tach Feedback generator was bad and re calibrated the pump. When we calibrated it is nuts on. When we start applying NH3 and N serve the Viper displays a rate of 32 and no vac or flow alarms, but we have applied over 100ac and only used a few gallons. Seems when we apply soom pressure to the pump from the NH3 or even our finger when we calibrate the pump does not apply the correct amount. Any Ideas? When the pump was torn apart did we not re install correctly? What are we missing? Is the pump just wore out? seemed to work just fine last spring.