Control Pressure Regulator Operation

With the engine stopped, or running with less than 0.1 bar boost, both springs operate against the control valve. The control pressure is high. Control pressure will drop (full load enrichment) when boost pressure at the top of the diaphragm exceeds 0.1 bar. The operation test for full load enrichment can be made only when the boost pressure is above 0.3 bar.

Vacuum

Electric Control of Fuel Pumps/Ignition System

Ignition Control Unit

Pressure

Manifold pressure

The 924 mixture control unit does not have an air sensor contact. The operation of the pump control is as follows: With the ignition switched on, the ignition coil (M),terminal 15, is energized (via 1.0 ft resistance wire). When starting the voltage flows from starter (B), terminal 16, to ignition coil terminal 15 and is thereby bypassing the 1.0 ft resistance wire. Impulses from the ignition control unit provide the electronic section of pump relay (K) with impulses and the relay closes. This will operate fuel pumps (L), control pressure regulator (F) and auxiliary air regulator (E) via terminals 30—87. The fuel pumps, the control pressure regulator, and the auxiliary air regulator are protected by a (25 amp) fuse.

A

— Battery

K

— Fuel pump relay

a

— To tachometer

B

— Starter

L

— Fuel pumps

b

— Plug 6-pole

C

— Thermo-time switch

M

— Ignition coil

c

— Plug 7-pole

D

— Cold starting valve

N

— Ignition distributor

E

— Auxiliary air regulator

0

— Ignition control unit

F

— Control pressure regulator

G

— Boost pressure control switch

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