Piper Dakota - Adjustment of Electric Fuel Pump; Assembly of Fuel Pump

ASSEMBLY OF FUEL PUMP (figure 28-4)
1. Insert plunger assembly (10) in tube with buffer spring end first. Check fit by slowly raising and
lowering plunger to see if it sticks. 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 retainer
spring securing components inside pump housing.
3. Place cover gasket and magnet in bottom cover with filter screw.
4. Carefully guide screen around plunger spring cap. Screen must fit snugly at both ends. Do not pinch or
distort screw. Draw bottom cover tight with a wrench and safety.
ADJUSTMENT OF ELECTRIC FUEL PUMP (BENCH TEST)
1. Ensure that pump is sufficiently lubricated to prevent damage if run dry for a period greater than 5
minutes.
2. Connect electrical lead of pump to a 14-volt dc power source.
3. Use a suitable container of proper octane fuel and connect a fuel line from container to inlet side of
pump.
4. Connect another line from outlet side of pump to a pressure gauge and bypass valve and back to
container.
5. Run pump with bypass valve open until a steady flow of fuel is obtained. Then close bypass valve and
check pressure gauge for proper reading of 6.5 to 7.5 psi maximum, no flow.
6. If proper pressure is not obtained, replace plunger spring and retest or if necessary, replace complete
pump assembly.
ADJUSTMENT OF ELECTRIC FUEL PUMP (IN AIRPLANE)
1. With cowling removed and fuel selector in OFF position, remove fuel line from outlet end of pump.
2. Connect a test line with a bypass valve and pressure gauge to outlet end of pump.
3. Place a container below pump to catch any fuel from test line during pump adjustment.
4. Turn fuel selector on, open bypass valve on test line, and start pump.
5. When a steady flow of fuel is obtained, close bypass valve and check reading on pressure gauge. It
should read 6.5 to 7.5 psi maximum, no flow. Do not keep bypass valve closed for more than 1 minute
during pump operation and adjustment.
6. If proper pressure is not obtained, replace plunger spring or if necessary, replace complete pump
assembly.
7. Reconnect original fuel line to pump. Open fuel selector and run pump to check for any fuel leaks.
8. Shut off pump, close fuel selector and replace and secure access panel.
28 - 23 - 00
Page - 28-10
Reissued: August 1, 1986
2B4
PIPER AIRCRAFT
PA-28-236
MAINTENANCE MANUAL