Manifold Pressure Compensator On 6800 Tractor; Cold Start Solenoid; Boost Control; Running Position - Valtra VALMET 6000 Service Manual

22. Fuel system
Manifold pressure compensator on
6800 tractor
(Bosch LDA)
Note! Boost control is fitted also on 8750 and 8950 tractors
which have SigmaPower system.
The boost control unit on the governor housing has been
connected via a hose to the engine inlet manifold. At low
revs the boost pressure is low and engine tends to smoke.
The boost control limits amount of injected fuel at low revs
so that exhaust gas emissions are below standard R24.
This adjustment starts at a certain, adjusted, boost pres-
sure.
The boost control unit membrane is pre ---tightened and air
tight. A spring in the unit affects the lower surface of the
membrane; the other end of the spring rests against the
threaded guide sleeve (2). The spring tension can thus be
changed in certain limits (adjusted in factory).
With thread equipped pin (1) is attached to the membrane.
The lower end of the pin transmits movement of the mem-
brane via an angle piece to the injection pump control rod
(3).
When increased boost pressure presses the membrane
downwards, also the pin moves downwards against the
spring force and allows the control rod to move towards the
greater fuel amount, which is injected into the combustion
chambers. When the boost pressure decreases, the control
rod moves towards the smaller amount of injected fuel.
Important! The boost control unit has been adjusted in the
factory, and adjustments afterwards are not necessary.

Cold start solenoid

Note! This solenoid is also fitted on 8750 and 8950 tractors.
When the engine is started, the control rod must move to
the starting position. This can be done by moving the boost
control lever in the direction of the axle, so that the lever
cannot affect any more the injection pump control rod.
The mechanism functions with aid of solenoid and a cross
shaft.
The solenoid is energised, when the ignition switch is
turned in a starting position. The solenoid is energised as
long as the starter motor is on. In the starting position, the
solenoid is magnetic. When the solenoid moves to the start-
ing position, a click sound can be heard from the injection
pump.
Model
15. 5. 1996
1. 6. 1999
3
Picture 1. Boost control
A. Adjustment screw with which is adjusted fuel amo-
unt, which the injection pump injects at low boost pres-
sure.
B. The operating pressure is adjusted by removing the
plug and by adjusting wheel B with a screwdriver.

Running position

117
Code Page
6800 223
9
A
1
B
2
1. Forced ---feed solenoid
for starting
Starting position