O.S. Engines PA-102 Carb - 72502000 - Manual

INSTRUCTIONS FOR O.S. PA-102 PUMP SYSTEM
The O.S. PA-102 Pump System consists of the unique O.S. Type PD-02 diaphragm fuel pump and matching
large-throat carburettor (O.S. Type 86) and has been developed specifically for 10 cc (0.61 cu.in.) class
FAI pattern contest engines.
The O.S. Pump System provides more power and ensures that fuel is delivered to the carburettor at the
pressure necessary to maintain optimum mixture strength, irrespective of fuel tank location or aircraft
attitude.
Fig.1
Fig. 2
PIPING
• For piping, use heavy duty silicone fuel tubing of ap-
proximately 2.5 mm bore and 5 mm outer diameter.
• A feature of the O.S. Pump System is that the fuel tank
does not have to be placed close behind the engine, but
tube lengths should be kept as short as possible. Take
care not to cause any kinks in the "plumbing".
PipeC
Fuel filter
Pipe A
Fuel flow
Pipe D
Pipe B
Pipe A: To draw the fuel from the fuel tank to the pump.
Pipe B: To deliver the fuel from the pump to the carburettor.
Pipe C: To pick up the boost pressure in the carburettor.
Pipe D: To return the excess fuel to the fuel tank.
FUEL TANK
If the fitting of the "klunk" type fuel pick-up weight in the
fuel tank is incorrect, the weight may stick to the tank wall,
resulting in an irregular fuel flow to the carburettor, or,
alternatively, in the fuel flow being cut off during the
course of sharp aerobatic manoeuvres. Therefore, it is
advisable to make slots in the end of the weight, with a file
or hacksaw blade, as shown in Fig. 4. Thoroughly wash
out the weight to remove any minute particles of metal
before reinstalling it in the tank.
Use thick silicone tubing.
10~15mm(3/8~5/8") Fig. 3
WARNINGS
Do not disassemble the pump
Never take the pump unit apart. Once the pump has been
dismantled, its original performance may not be restored
when it is reassembled.
Do not insert anything into the nipples
Inserting a pin, etc., into the nipples is likely to damage the
pump and render it inoperative.
Use fuel filters
Any foreign matter entering the Pump System may inter-
fere with its correct functioning and may even damage the
pump diaphragm. Be sure to filter all fuel before filling the
tank and, most important, use a good quality fine filter in
the delivery tube between the tank and pump.
Do not attempt to adjust the pump screws
Both adjusting screws are accurately adjusted and sealed
with paint at the factory. If the screw setting is disturbed,
it cannot be re-set at its optimum position without the aid
of special instruments.
INSTALLATION
Here is an example of a typical installation.
(Top view, upright engine installation.)
Connect to 'IN' nipple
of the pump.
Disconnect here when
f i l l i n g the tank.
Silicone tubing
L-shaped nipple or aluminum
tubing
Pipe to return excess fuel
to the tank. Overflow
It may be convenient to lead the
pipes outside the fuselage and
connect with a p p r o x . 35mm (1 1/2")
length of silicone tubing.
Note: A fuel filter is omitted in the above sketch.
STARTING THE ENGINE
1. Fill the fuel tank.
2. Open the needle-valve approx. 2 ~ 2-1/2 turns from the
fully closed position.
3. Turn the propeller by hand, while watching fuel pipes A
and B, until fuel is pumped as far as the carburettor. It
may be necessary to turn the propeller through about 20
revolutions, depending on the length of pipe from tank
to pump. Make a mental note of the number of revolu-
tions required for fuel to reach the carburettor. However,
note that it may be necessary to turn the propeller a few
more revolutions if the pump is being used for the first
time, or if no fuel has remained in the pump from
previous use.
Fig. 4