Bronco L6-300 4.9L VIN Y 1-bbl (1983)
Accelerator Pump: Description and Operation
Fig. 28 Temperature compensated accelerated pump. Motorcraft model 2150A carburetor
The temperature compensated accelerator pump, Fig. 28, is used on vehicles equipped with the Motorcraft 2150A model carburetor, allows delivery
of a large pump capacity to facilitate cold engine requirements and a smaller pump capacity during warm engine operation. The amount of fuel delivered
during warm engine operation is a function of the rate at which the accelerator pedal is applied (fast application/low capacity, slow application/high
capacity). The design incorporates a bypass bleed controlled by a vacuum operated valve. Normally, the input signal controlling the valve position is
manifold vacuum switched by a PVS located in the engine coolant system. The valve is normally closed when no vacuum is applied, allowing full pump
capacity during cold operation. With vacuum applied, the pump functions as a rate sensitive valve controlling the amount of fuel bypassed back to the
carburetor fuel bowl and not delivered to the intake manifold air stream.
