Aneroid control for fuel injection pump

A controller for adjusting the quantity of fuel delivered by a fuel injection unit pump, said controller comprising:

• a base defining a control piston bore;
• a control piston received in said control piston bore for axial reciprocation therein;
• a rack rod connected to said control piston for axial movement therewith;
• a source of engine oil pressure, said engine oil pressure increasing from a first low pressure at engine start up to a second higher pressure after engine warm up;
• a source of engine intake manifold air pressure, said intake manifold air pressure increasing when the engine is under load;
• first control means for controlling the axial position of said control piston in response to said engine oil pressure;
• and
• second control means for controlling the axial position of said control piston in response to said engine intake manifold air pressure,
• wherein at said first oil pressure the axial position of said control piston is a function of the oil pressure and at oil pressure above a pre-established threshold between said first and second pressures, the axial position of said control piston is a function of the intake manifold air pressure, said control piston moving axially to increase fuel delivery in response to engine oil pressure below said pre-established threshold or increased intake manifold air pressure.