82 4 DLT ENGINE diaphragms within the boost controller. The boost pressure is piped and connected to the chamber formed between the two diaphragms. The diaphragms sense the variation in the boost pressure and maintain the balance between the fuel delivery and the boost pressure, by continuously varying the pressure behind the actuating pistons. Operation : At cranking speeds, the assembly is held in Excess Fuel position (Full Boost) by a spring. As the engine picks up, the transfer pressure builds up behind the actuating pistons and moves the assembly to minimum fuel position. As the boost pressure increases with the rise in engine speeds, the diaphragm responds and allows the pressure to leak acting behind the actuating pistons. This allows the return spring to move the assembly axially towards increased fuel delivery position. 6. EGR THROTTLE SWITCH The EGRThrottle Switch fitted on to the throttle lever is used to sense the position of the throttle lever. The output is given EGR controller. 7. COLD IDLE ADVANCE The Solenoid operated Cold Idle advance is driven by the glow plug timer (GPT) and overrides the normal advance control mechanism when the engine is cold. This normally functions in conjunction with the engine Pre / Post heat system and operates only when the electrical input is supplied to it by the GPT. AIRVENTING The DPC pumps are self venting pumps and therefore allows the air entering into it, to go out through the return line. However, it is recommended that whenever the fuel lines are disconnected, the system is to be primed in order to fill the system with fuel and remove the air present in the system completely. Procedure l Energise the Fuel Shut-Off Solenoid (Switch 'ON' the ignition switch). l Loosen the following vent screws On the banjo bolt at the filter outlet ➀ On the FIP timing chimney plug ➁ (See fig. 166) l Loosen the priming pump plunger ➂ and actuate the pump until clear fuel comes out of the vent screw ➀ l Tighten the vent screw ➀ l Continue actuating the priming pump plunger until clear fuel is seen coming out from the vent screw ➁ l Tighten the vent screw ➁ and then the priming pump plunger ➂ Loosen one of the HP connections at the injector end. Crank the engine for few seconds; and see that the fuel flows out of the injector line.Tighten the HP connection. Start the engine and see that there is no fuel leak from any of the points/connections. Fig. 166 2 1 3
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