The level of petroleum accumulating from a production zone as it is pumped from a lower elevation in a wellbore is remotely monitored by using the energy of a sucker rod driven pump. One or more sensors are interposed between sections of the sucker rod between the production zone and the pump level. The sensors include trigger mechanisms moving with the sucker rod string within spring loaded and slidable pistons. Over a short span the reciprocating triggers engage deformable sleeve actuators which slide and spring load the pistons. When the triggers pass through the sleeve actuators, they release the piston which impacts against a pressure wave or sonic signal generator. The impacted elements transmit a signal up to the wellhead indicative of the presence or absence of petroleum at that elevation. One or two sensors, and optionally other inputs as well, can be used in adjusting the pumping rate to maximize production.