Warm Up Regulator: Description and Operation

Fig. 1 Control Pressure (Warm Up) Regulator:

The control pressure regulator ,Fig. 1, determines the fuel pressure on top of the control plunger to help regulate the air/fuel mixture, primarily during engine warm-up.
Control pressure on top of the control plunger in the fuel distributor is supplied through a small hole in the fuel distributor separator plate. This enables control pressure to be regulated without affecting system pressure. Another restriction dampens control plunger movement so that it changes position smoothly.
When the engine is cold, the bi-metallic strip presses on the spring causing the fuel line to open, reducing control pressure.
Heat from the engine and the heating coil which is connected to the fuel pump circuit straightens out the bi-metallic strip. The spring closes the return line so that control pressure gradually increases as the engine warms up.