Fig. 14. - The Buma Fuel Pump Valve-seating Tool.
adapter, will quickly reface any
worn seating. It is hand
operated, and is supplied with
alternative sizes of screw-in
adapters and cutters to seat the
various A.C. pump models.
Care of the Petrol
System
The following notes refer to
the most likely troubles to be
met with in petrol systems of the
fuel-pump class.
1. Leaky Tube or Connections.
- Renew tubing and tighten all
pipe connections at the fuel
pump and petrol tank.
2. Top Pump Cover Loose. - Tighten nut, making certain that the cork
gasket lies flat in its seating and is not broken.
3. Dirty Screen. - Remove cover and clean screen. Make certain that
the cork gasket is properly seated when reassembling.
4. Loose Valve Plug. - Tighten valve plug securely. Renew valve-plug
gasket if necessary.
5. Dirty or Warped Valves. - Remove valve plugs and valves. Wash
valve in petrol. If damaged or warped, renew them. Examine valve
seating, making certain there are no irregularities which prevent proper
seating of valves. Place valve in valve chamber with the polished side
downwards, making certain that the valve lies flat on its seat and is not
left standing on edge. Dismantle valve plug and spring and make certain
that the spring is around the lower stem of the valve plug. Use new gasket
under valve plug if necessary.
6. Choked Petrol Supply. - Remove screen from pump and clean thoroughly
in petrol. If necessary dismantle pipeline and blow through with an air
pump to remove any obstruction. A second filter will be found in the car
burettor and this also should be thoroughly cleaned by washing in petrol.
The A.C. Petrol-pump Test Stand
Many unnecessary repairs can be avoided by testing all pumps before
dismantling.
The A.C. Petrol-pump Test and Assembly Stand (Fig. 15) will be
found invaluable in all cases where the working of a pump is under
suspicion. Complete instructions as to the method of using the stand
are supplied with each apparatus, and it is therefore only necessary to
mention the following:
Fig. 15. - The A.C. Petrol-pump Test Stand.
Before attempting
repairs of any kind,
mount the pump on
the stand, attaching
firmly with the wing
nuts and bolts pro
vided. Attach hose to
inlet and outlet sides of
pump, turning connec
tions up tightly with
wrench. Then actuate
rocker arm by hand.
If pump will prime
(i.e. commence to de
liver fuel) with twenty
strokes or less, then
close the shut-off valve
on the outlet side and work the rocker arm until 1.1/2-lb. to 2.1/2-lb. pressure
is indicated on the gauge. If valves are seating properly, and there are no
leaks in pump or connections, pressure will hold for several seconds before
hand gradually returns to zero.
If pressure does not hold, look for leaks around diaphragm or for worn
valves or punctured diaphragm. Make repair with pump mounted on
stand. When completed, retest, examining for leaks.
Testing Pump on the
Vehicle. - Another useful
testing device is the A.C.
petrol pump analyser, which
is employed for checking the
performance of these pumps
under actual operating con
ditions. The analyser men
tioned will test a pump
whilst the engine is running
under its own power for
capacity or petrol flow and
pressure.
Fig. 16 shows the A.C
fuel pump analyser which
is used for making fuel-pump
tests without removing the
pump from the vehicle. It
is designed for fuel flow rate
and pressure tests. A flexible
connection is provided for
the pump outlet and, with
Fig. 16. - The A.C. Fuel-pump Vehicle Test Apparatus.