As the engine speed increases, the transfer pressure rises, moving the piston against the pressure of the regulating spring to progressively uncover the regulating port in the valve sleeve and allow a metered flow of fuel to bypass back to the inlet side of the transfer pump. When the injection pump is in operation fuel at transfer pressure enters the lower end of the valve sleeve, forcing the ‘free’ piston upwards against the regulating spring.

The priming port is connected by a passage in the end plate to the delivery side of the transfer pump, thus enabling the fuel to by-pass the stationary transfer pump and prime the injection pump. When priming the injection pump, fuel at lift pump pressure enters the central port in the regulating-valve sleeve and moves the ‘free’ piston against the pressure of the piston retaining spring to uncover the priming port in the lower end of the valve sleeve. Ca.3, it will be seen that the valve is cylindrical and contains a small ‘free’ piston, the travel of which is limited by two light springs. The pressure regulating valve, in addition to regulating the pressure of the fuel from the transfer pump, also provides a means of by-passing the transfer pump when priming the injection pump. This pump raises the fuel pressure to an intermediate level, and as its capacity is many times the maximum requirements of the injection pump a regulating valve, housed in the pump end plate, allows excess fuel to be by-passed back to the suction side of the transfer pump. Mounted on the outer end of the pumping and distributing rotor is a sliding-vane-type transfer pump.

A central rotating member forms the pumping and distributing rotor, and this is driven by the drive hub through a splined drive shaft on which is mounted the governor flyweight assembly. A splined quill shaft, having a master spline at each end to ensure correct location, transmits the drive from the chain wheel to the injection pump drive hub.

The pump is flange-mounted on the rear of the engine front mounting plate and is driven by the timing chain. DESCRIPTION OF THE FUEL INJECTION PUMP The injection pump is a single-cylinder, opposed-plunger, inlet-metering, distributor-type pump fitted with a mechanical flyweight-type governor and a hydraulically operated automatic advance mechanism. PLEASE MAKE SURE YOU MATCH THE SAME EXACT PART NUMBER BEFORE PURCHASING IT. Lucas CAV DPA Fuel Injection Pump Fits Massey Ferguson Perkins Diesel 3248F391 ALT NUMBER: DPA3248F391 0006MUP LS57.0L8 36532/36538/36549/37858/38328 IF YOU WANT TO RETURN THE ITEM PURCHASED WE CHARGE 15 % RESTOCKING FEE. Item: 372814484438 Lucas CAV DPA Fuel Injection Pump Fits Massey Ferguson Perkins Diesel 3248F391.

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