A power cutter comprising: a housing; a two stroke internal combustion engine mounted within the housing; a throttle switch by which the engine can be accelerated when the engine is running; a support arm mounted on the housing and which projects forward of the housing; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine 24 when the engine is running; a carburettor for providing aerated petrol for the engine; an air intake for providing air for the carburettor; an air filtration mechanism to filter the air drawn in from the air intake for the carburettor; a petrol tank for providing petrol to the carburettor; and an exhaust through which the exhaust gases generated by the operation of the engine are expelled from the engine; characterized by an engine controller which controls the operation of the engine; an oil tank for providing lubricating oil for the engine; an oil pump to pump lubricating oil from the oil tank to mix it with petrol, wherein the oil pump comprises a piston which can axially slide within a housing over a limit range of axial movement which is determine by a stop mechanism, wherein a spring biases it to a predetermined position, and wherein a solenoid surrounds the piston and moves it axially when an electric current is applied; and a sensing system which determines whether sufficient lubricating oil is being provided for mixing with the petrol in accordance with predetermined parameters, wherein the sensing system provides an indication to the engine controller of when the lubricating oil is not being provided in accordance with the predetermined parameters, the engine controller placing the engine either in an idle mode or switching it off when the sensing system indicates that the lubricating oil is not being provided in accordance with the predetermined parameters; wherein the oil pump is power by an electrical power supply, the sensing system comprising monitoring means which monitors the voltage and current of the electrical power supply of the oil pump during the operation of the oil pump and determines whether lubricating oil is being pumped by the oil pump by analyzing the values of the voltage and/or current of the electrical power supply to determine whether sufficient lubricating oil is being provided compared with predetermined parameters and providing an indication to the engine controller when the lubricating oil is not being pumped in accordance with the predetermined parameters. a housing; a two stroke internal combustion engine mounted within the housing; a throttle switch by which the engine can be accelerated when the engine is running; a support arm mounted on the housing and which projects forward of the housing; a blade mounting mechanism (70, 90, 86, 92) rotatably mounted on the end of the support arm and which is capable of being rotationally driven by the engine 24 when the engine is running; a carburettor for providing aerated petrol for the engine; an air intake for providing air for the carburettor; an air filtration mechanism to filter the air drawn in from the air intake for the carburettor; a petrol tank for providing petrol to the carburettor; and an exhaust through which the exhaust gases generated by the operation of the engine are expelled from the engine; characterized by an engine controller which controls the operation of the engine; an oil tank for providing lubricating oil for the engine; an oil pump to pump lubricating oil from the oil tank to mix it with petrol, wherein the oil pump comprises a piston which can axially slide within a housing over a limit range of axial movement which is determine by a stop mechanism, wherein a spring biases it to a predetermined position, and wherein a solenoid surrounds the piston and moves it axially when an electric current is applied; and a sensing system which determines whether sufficient lubricating oil is being provided for mixing with the petrol in accordance with predetermined parameters, wherein the sensing system provides an indication to the engine controller of when the lubricating oil is not being provided in accordance with the predetermined parameters, the engine controller placing the engine either in an idle mode or switching it off when the sensing system indicates that the lubricating oil is not being provided in accordance with the predetermined parameters; wherein the oil pump is power by an electrical power supply, the sensing system comprising monitoring means which monitors the voltage and current of the electrical power supply of the oil pump during the operation of the oil pump and determines whether lubricating oil is being pumped by the oil pump by analyzing the values of the voltage and/or current of the electrical power supply to determine whether sufficient lubricating oil is being provided compared with predetermined parameters and providing an indication to the engine controller when the lubricating oil is not being pumped in accordance with the predetermined parameters.