Fuel delivery meter

A fuel delivery meter for measuring and indicating the quantity of fuel delivered by engine fuel injection means "on test," the said meter comprising a chamber, a first opening in said chamber for receiving fuel delivered by engine fuel injection means, a spring-loaded piston within the chamber arranged to be displaced by fuel entering the chamber, indicating means operatively connected to the said piston so as to be actuated by displacement of said piston to give a reading which corresponds to the amount of fuel which has entered said chamber, at least one further opening in said chamber on that side of the piston remote from said first opening, a fuel circuit including fuel flow means for passing delivered fuel into said chamber through said further opening so as to warm the meter, and a simple solenoid-operated valve in said fuel circuit together with a three-port solenoid-operated valve, the said three-port valve serving to control the flow of fuel into the chamber to displace the piston and also to permit the flow of fuel into the chamber on that side of the piston remote from said first opening so as to warm the meter, and said simple solenoid-operated valve serving to control the flow, out of the chamber, of that fuel received by the chamber to displace the piston.