clean out the sediment chamber, using a non-fluffy rag. Clean the filter
gauze in an air jet or fuel.
The cork washer under the filter cover should be renewed if broken or
if it has hardened, since it is essential for the pump cover to make a fuel-
tight joint with the pump body.
For the same reason, when refitting the cover make certain that the
fibre washer is replaced under the head of the screw.
Tighten the filter cover retaining screw just sufficiently to make a
Check the pump to crankcase mounting bolts for tightness; also check
fuel-tight joint. Over-tightening will either destroy the cork washer,
crack the cover, or fracture the main casting.
the fuel-pipe unions.
Dismantling Fuel Pump for Overhaul. - The pump is removed
from the engine by first disconnecting the pipe unions and then the nuts
holding the pump to the engine crankcase. Before dismantling the fuel
pump, clean the exterior and make a file mark across the two flanges for
reassembly purposes. Next separate the two main castings, when the
components of each can readily be dismantled and the parts placed in a
clean box or tray.
The diaphragm and pull-rod assembly can be withdrawn by first
turning it through 90
0
. No attempt should be made to separate the four
diaphragm layers from their protector washers and from the pull rods, as
this is always serviced as a complete unit, being riveted together.
Examination of the Components. - Before examining the dismantled
parts (Fig. 12), they should be washed in a paraffin bath.
Diaphragm and pull-rod assemblies should normally be renewed unless
in entirely sound condition without any signs of cracks or hardening.
Upper and lower castings should be examined for cracks or damage,
and if diaphragm or engine mounting flanges are distorted these should be
lapped to restore their flatness. Where hand priming lever L (Fig. 10)
incorporated in lower casting is broken, the parts should be replaced, the
outer end of the spindle being riveted over by hand tools after correctly
locating the various components.
All badly worn parts should be replaced, and very little wear should be
tolerated on rocker-arm pins (20) (Fig. 12), the holes and engagement slot in
link (25), or hole in rocker arms (23). On the working surface of the rocker
arm, which engages with the engine eccentric, slight wear is permissible, but
not exceeding .010 in. in depth. The valve seat incorporated in valve plate
(14) should be examined, and if at all roughened should be carefully lapped
flat on a smooth carborundum stone; similarly, the corresponding outlet
valve seat incorporated in the upper casting (6) should be examined, and
if worn unevenly to the slightest degree both the upper casting and valve-
seat assembly must be replaced. It is not practicable to refit new valve
seats into the castings as this calls for special equipment.
Fuel-pump valves (12) should be renewed if at all worn, although in an
emergency they can be turned over to provide a fresh surface to the valve
Fig. 12. - Showing Complete Components of Austin A.C. Petrol Pump.
1, Top Cover Screw.
2, Cover Screw Washer.
3, Pump Top Cover.
4, Cork Sealing Washer.
5, Filter Gauze.
6, Upper Chamber.
7, Drain-plug Joint Washer.
8, Drain-plug Washer.
9, Drain Plug.
10, Spring Retainer.
11, Valve Springs.
12, Valves.
13, Valve-plate Gasket.
14, Valve-retainer Plate.
15, Valve-plate Screw.
16, Priming-lever Spring.
17, Lower Casting.
18, Rocker-arm Stop Screw.
19, Stop-screw Washer.
20, Rocker-arm Pin.
21, Rocker-pin Washers.
22, Rocker-arm Pin Clips.
23, Rocker Arm.
24, Anti-rattle Spring.
25, Rocker Link.
26, Diaphragm Spring.
27, Diaphragm and Pull Rod.
seat. Valve springs (11) should be preferably renewed, although they can
be refitted providing they do not bear undue evidence of rubbing away
on the outside diameter. In no circumstances should valve springs be
stretched in an endeavour to increase their strength. Diaphragm springs
(26) seldom call for replacement, but where necessary ensure that the
replacement spring has the same identification colour and consequently the
same strength as the original. Rocker-arm springs (24) are occasionally
found to be broken after long service. All gaskets and joint washers should
be renewed as a matter of routine.
Reassembling the A.C. Fuel Pump. - The following procedure