Fuel Pump, Bendix Plunger Type - Piper PA-24 Comanche Service Manual

PiPeR COMANCHE SERVICE MANUAL
is cained.
b. Turn the fuel selector valve to the off position.
c. DiscoMect fuel tines and electrical lead.
d. Remove the bolts securina the pump(s) and remove from aircr.ft. Do not allow dirt or for-
eign matter to enter the open fuel lines. .
e. To install fuel pump(s), secure to the mOWltiAI bracket of the aircraft.
f. Check the fuel lines and pump(s) that no dirt ha. entered the fuel system. COMect the fuel
lines md elee:uical lead. Ascertain that eech pump h.. a
1*
1P'000d.
C. Turn on the m.ster switch, pump ••itch and open the line on the outside
oJ.
the pump to
PIUP
any
air. Resecure the line and check for luelle_lea.
h. Operate the anline for a short time .nd tben clean the inlet screen to the carburetor or
injector.
t-26. Fuel Pump, Bendix Plun,.r T1,..
(PA-24-180, PA-24-2S0
_d
PA-24-260 with carburetor
induction.) These pumps are desillled with a solenoid, whicb wbea enerai.ed -ctivate. a hollow
plunaer. The plunaer stroke is controlled by • set of intemaptiac points in the electrical circuit
and a calibrated plun.r sprina. The interrupter system ia s.aled in cas .tmosphere. 1f any of
the electrical compcneltts become inoperative, the camp.te pump mUlt
be
repleced.
Field service is limited to the .stent of cleaninc the bcctom cover, filter screen, plunger
tube and j)lunlet assembly. On the PA-24·180 and PA-24-2S0 aircraft, pWllp intemal parts differ
with the early style (refer to lip. 8-15) and the late style (refer to ficure 8-16).
On the PA-24-260
only tbe late style pump is used.
1.
Early PIWlCer Pump. (Refer to Fiaure 8-lS.)
a. To service the .arly pump, detach from the aircraft and Nmove the bottom
eevee
(1) and
filter screen (4) as explained in paralraph 8-22.
b. Disassemble the pluftler spring cup (8) by Nmoviftl the three screws (3) s.curing the
cup. Gently touch the plastic cup valve (5) with your finler. If it i. free, do not remove the valve
sprine. Do not apply air pressure to this assembly. Use lonl no.e pliers to replace valve as-
s.mbly if it falls out of the cup. It will click when the ..sembly is properly seated.
c. Pull the pluncer sprine (9) and plunaer ....mbly (10) from
the
pump with your finlers.
00
not drop or mutilate the pluqer. Th. buffer sprine and valve (i) must not
be
removed from the
plung.r. Wash the plunler a..embly in luoliDe or a reliable solvent. If it does not wash clean
at
if there are any rouch spots, gently dress with crocus cloth.
d. Shake the plunl.r u.embly md listen for click to indicate valve action. If valve is not
iree, replace plutlC.r assembly. SIQlh the pump assembly in I.soline
01 •
solvent. Swab the tube
with a cloth wrapped stick and blow out with air presawe.
e. Reass.mbl. the unit
by
insertina the plunler ....mbly in the tube witb the buffer spring
end first. Ch.ck fit by sla.... ly raisina and 10weriDi the plunler in the tube. It should move freely
WIthout any tende!\cy to stick. A click will
be
heard eech time the plunger approaches the top of
tube. If the click cannot be heard, t.'te in·errupter assembly is not functioning properly. Replace
the pump. To finish the reassembly, install the plunler sprina cup Casket (use a :lew one) and
the plunger spring cup. Draw the screws to a snug fit, but not over tiaht. Be sure the cue is not
cocked to prev.nt the pluncer from bindinl in the tube.
£. P!ac. the iilt.r screen atOWld the bottom cover maanet. twist the cover with your fincers
and carefully guide the screen around the plung.r sprinc cup. The screen must fit snugly at both
ends. 00 not pinch or disto"t the screen. Install the cov.r and safety. Install on altcraft and
FUEL SYSTEM
ISSUED: 8118n2
2J8
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