Piper Arrow IV, Maintenance Manual

Page: 601 / 752

Figure 73-6. Exhaust Bypass Screw
A. Set the engine at 40.8 to 41.0 in. Hg manifold pressure (overboost light activated) and engine at
2575 + 25 RPM. Readjust the throttle as required to maintain 40.8 to 41.0 in. Hg manifold.
B. Fuel flow should be 23.0 to 23.5 gallons per hour (gph), with the mixture controls in the full rich
position.
C. If adjustment is required, loosen the jam nut on the adjusting screw located on the aneroid housing
of the fuel pump. (Refer to Figure 73-5, item 2.) Clockwise adjustment decreases fuel flow
reading; counterclockwise adjustment increases fuel flow reading; one full turn will cause a 1.0 to
1.5 gph change. Use CAUTION when loosening and tightening the jam nut so as not to change
settings or over torque the jam nut.
—NOTE—
If other than minor adjustments are required to the fuel flow, a
complete investigation of interface systems is required.
8. Rechecking System:
A. Recheck the idle settings per instructions 3, 4, 5 and 6, and adjust as required.
B. Recheck Full Power Fuel Flow settings per instruction 7, and adjust as required.
C. With engine operating at 2575 RPM (40.8 to 41.0 in. Hg manifold pressure), lean the mixture to
obtain 21 gph fuel flow readings. The unmetered fuel pressure on the calibrated pressure gauge
should be 40 to 43 psi.
Effectivity 73-20-02
PA-28RT-201T Page 73-08
December 1, 1978
3C21
PIPER AIRCRAFT
PA-28RT-201 / 201T
MAINTENANCE MANUAL