
CARBURATION AND FUEL INJECTION 123
contact-breaker points, thereby interrupting the circuit
and de-energizing the solenoid coil. This then releases
the spring returned armature, which thus allows the
diaphragm to advance into the pumping chamber on its
delivery stroke. The ensuing build-up of pressure causes
the inlet valve to close and the outlet valve to open
(Figure 6.8b). When the armature approaches the end
of its delivery stroke, the toggle switch once again
throws over, this time to restore the circuit to the
solenoid coil by closing the contact-breaker points, so
that the pumping cycle can be repeated. Again, the
pump must cease to