Workshop
Manual
Rolls Royce Silver Shadow
b
Bentley
T
Series
Chapter
K
SYMPTOM
Fuel
Pumps-continued
2.
Fuel flow initially correct, then
diminishing rapidly resulting in
slow pump operation. Inade-
quate ventilation of the fuel
tank causes a slow power stroke
with resultant excessive burning
of the contact points.
3.
Reduced fuel flow with rapid
operation of the fuel pump.
4.
As
Symptom
I.
5.
Fuel pump operates without
fuel delivery.
6.
Noisy pump operation.
POSSIBLE CAUSE
(f) Obstruction in the pipe line bet-
ween the fuel tank and the pump.
This fault
uscally causes over-
heating of the pump.
2.
(a) Insufficient fuel tank ventilation.
(b) Restriction on the suction side
of the pump.
3.
(a) Air leak on the suction side of
the pump or faulty sealing
washers.
4.
(a) If all the preceeding operations
fail to locate the fault, stiffening
of the diaphragm or
abnormal
friction in the rocker 'toggle
over' mechanism should be sus-
pected.
5.
(a) Serious air leak on the suction
side of the pump.
(b) Dirt lodged under one of the
valves particularly the inlet valve.
6.
(a) Air leak in suction line.
I
ACTION
(f) If the fuel pump operates cor-
rectly with the pump inlet pipe
disconnected, the trouble is due
to an obstruction in the pipe
line between the fuel tank and
the pump.
Remove the fuel tank filler cap,
then blow compressed air
through the inlet pipe.
Note
Compressed air sho~lld
not be passed through the pump,
asthis will cause serious damage
to the valves.
Refer to Action
2
(b).
2.
(a) Remove the filler cap. If this
cures the fault remove any
blockage or obstruction from
the fuel tank vent pipe.
(b) Check that the rear fuel filter is
not choked; if necessary renew
the filter element. Ensure that
the pump supply pipe from the
fuel tank is unobstructed.
3.
(a) Check for air leaks and the con-
dition of the
pump sealing
washers.
Remove the inlet and outlet
valve assemblies from the pump
(see
Fig.
K7).
Check that the
assemblies are clean and that
they operate freely.
4.
(a) Remove the solenoid housing,
then flex the diaphragm several
times. Care should be taken not
to lose any of the eleven brass
rollers (if fitted) from beneath
the diaphragm.
Prior to assembly, it is advisable
to apply several drops of thin
oil to the 'toggle over' spring
spindles at the point where they
pivot in the brass rockers.
Assemble and set the diaphragm
armature assembly (see Section
K2-Solenoid housing and dia-
phragm-To
fit).
5.
(a) Check that the inlet flexible pipe
and union are tight.
(b) Remove the valves for cleaning.
6.
(a)
Disconnect the fuel pipe at the
carburetter and allow the pump
to discharge into a fuel filled
container with the end of the
pipe submerged.
The emission of continuous bub-
bles at this point will confirm
the existence of an air leak.
To Next Page
Loading...
