PIPER AIRCRAFT, INC.
PA-28-161, WARRIOR III
MAINTENANCE MANUAL
PAGE 4
Nov 30/06
2K4
28-20-00
D. Cleaning, Inspection, And Repair
(1) Clean all parts with acetone or a suitable dry type solvent. If plunger assembly does not come
clean or there are any rough spots, polish gently with crocus cloth.
(2) Inspect pump for the following:
(a) Check filter screen for damage or distortion.
(b) Gently touch cup valve and check for freedom of movement. Do not disassemble.
(c) Shake plunger assembly and listen for clicks to indicate valve action.
(d) Check O-ring condition.
(e) Check cover gasket and plunger spring cup gasket condition.
(3) Pump repair is limited to replacement of defective parts during inspection.
E Assembly (Refer to Figure 2.)
(1) Insert plunger assembly (10) in tube (buffer spring end first). Check fit by slowly raising and
lowering plunger, (test for sticking). If a click cannot be heard, interrupter assembly is not
functioning properly and pump must be replaced.
(2) Install component parts in the following order: Cup valve, O-ring seal, and washer. Install the
retainer spring securing components inside pump housing.
(3) Place cover gasket and magnet in the bottom cover with filter screw.
(4) Carefully guide screen around plunger spring cup. Screen must fit snug at both ends. Do not
pinch or distort screw. Draw bottom cover tight with a wrench, and safety.
F. Testing
(1) Bench Test
(a) Check pump is sufficiently lubricated to prevent damage if run dry for more than five minutes.
(b) Connect electrical lead of one pump to 28-volt dc power source.
(c) Using a suitable container with the proper octane fuel, connect a fuel line from a container
to inlet side of pump.
(d) Connect another line from outlet side of pump to a pressure gauge and bypass valve, and
back to the container.
(e) Run pump with bypass valve open until there is a steady fuel flow. Close bypass valve and
check pressure gauge for 4.00 to 4.75 psi maximum, no flow.
(f) Replace plunger spring or the complete pump assembly, if necessary, if the proper
pressure is not obtained.
G. In Airplane
(a) With cowling removed and fuel selector in the OFF position, remove fuel line from outlet
end of pump.
(b) Connect a test line with a bypass valve and pressure gauge to pump outlet end.
(c) Place a container below pump to catch any fuel from test line during pump adjustment.
(d) Turn fuel selector on, open bypass valve on test line, and start pump.
(e) When there is a steady fuel flow close bypass valve and check pressure gauge reading.
Reading must be 4.00 to 4.75 psi maximum, no flow. (Do not keep bypass valve closed for
more than one minute during pump operation and adjustment.)
(f) Replace plunger spring or pump assembly, if necessary, if the proper pressure is not
obtained.
(g) Connect the original fuel line to pump. Open fuel selector and run pump. Check for fuel leaks.
(h) Shut off pump, close fuel selector, and replace and secure access panel.
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