Piper Comanche PA-24 Service Manual page 644

PIPER COMANCHE SERVICE MANUAL
is pinee!.
b. Tum the fuel selector valve to the off position.
c. Disconnect fuelli.,.s and electrical lead.
d. Ramo,,", the bolts securinl the pump(s) and remove fram aircraft. Do not aUow dirt or for-
eian mlltter to enter the
0
pen fue I lines.
e. To instaU fuel pWllp(S), secure tn the lIIountinl bracket of the aircraft.
f.
Check the fuel Une. and pump(s) that no dirt has entereel the fuel system. COrll\ect the fuel
Unes and electrical lead. Ascertain that each pump has a
,oad
around.
I. Turn on the m .. ter switch, pump switch and opeD the line on the outside d. the pump to
parae any air. Resecure the Une and chec k for fue I leaks.
h. Operate the en&ine for a short time and then clean the inlet screen to the carburetor or
injector.
~-26.
Fuel PUOlP, Bendix Plunge, Type. (PA-24-180, PA-24-2S0 and PA-24-260 with carburetor
'c'
duction.) These pumps are designee! with. solenOid, which when en'"'lind activates a hollow
plunger. The plunger stroke is controlled
by
a set
of
interruptinl points in the electrical circuit
and a calibratee! plun"" spring. The interrupter systam is sealed in gas atmosphere.
If
any of
the electrical components become inoperative, the complete pump must be .. placee!.
Field service is limited to the eKlent of c1eaninl the bottom cover, filter screen, plunger
tube and plunger assembly.
On
the PA-24-180 and PA-24-2S0 aircraft, pump intemal parts differ
with the early style (refer to figure 8-15) and the late style (refer to figure 8-16). On the PA-24-260
only the late style pump is used.
L Early Plunger Pump. (Refer to Figure 8-lS.)
a. To service the early pump, detach from the aircraft and remove the bottom cover (1) and
filter screen (4) as explained in paragraph 8-22.
b. Disassemble the piunger spring cup (8)
by
removin, the three screws (3) securing the
cup. Gently touch the pla.tic cup valve (5) with your finger. If it is free, do not remove the valve
spring. Do not apply air pressure to this assembly. Use long nose pliers to replace valve as ..
sembly if it falls out of the cup. It will click when the assembly is properly seated.
c. Pull the plunger sprIng (9) and plunger assembly (10) froD! the pump with your fingers.
Do not drop or mutilate the plunger. The buffer sprinll and valve (7) must not be removed from the
plunger. Wash the plunger assembly in g .. oUne or • reliable solvent.
If
it does not wash clean
or if there are any rough spots, gently dress with crocus cloth.
d. Shake the plllnier assembly and listen for click to indicate valve action.
If
valve is not
free, replace plunger assembly. Slosh the pllmp assembly in ,asoline
01
a solvent. Swab the tube
with a cloth wrapped stick and blow OIIt with air pressure.
e. Reassemole the unit
by
inserting the plunKer assembly in the tube with the buffer spring
end first. Check fit by slO"Nly raising and iowering the pillnger in the tube. It should move ireely
wlthout any tende!'lcy to stick. A click will
be
heard each time the plunger approaches the top of
tube. If the click cannot
be
heard, the inperrupter assembly is not functionUl& properly. Replace
the pump. To finish the reassembly, install the plunger
spring
cup gasket (use a
:leW
one) and
the plunger
spung
cup. Draw the screws to a snug
tit, but not over tight. Be sure the
CUD
is not
cocked to prevent the plunger from binding in the tube.
£. PIacethe iilter
Screen
around the bottom cover magnet, twist the cover wah your fingers
and carefully guide the screen around the plunger spring cup. The screen must fit snugly at Joth
ends. Do not pinch or
disto~
the screen. Install the cover and safety. Install on auctan and
2J8
FUEL SYSTEM
ISSUED: 8/18172