Piper Pawnee Brave Service Manual page 253

PAWNEE BRAVE SERVICE MANUAL
8A-25. FUEL INJECTOR.
8A-26. FUEL INJECTOR MAINTENANCE.
a.
In general, little attention is required between injector overhauls. However, it is recommended
that the following items be checked during periodic inspection of the engine; torque all nuts to 135-150
inch-pounds. Seat pal type nuts finger tight, against plain nuts, and then tighten an additional 1/3 to 1/2
turn.
1.
Check tightness and lock of all nuts and screws which fasten the injector to the engine.
2.
Check all fuel lines for tightness and evidence of leakage. A slight fuel stain adjacent to the
air bleed nozzles is not cause for concern.
3.
Check throttle and mixture control rod ends and levers for tightness and lock.
4.
Remove and clean the injector inlet strainer at the first 25 hours of operation and each 50
hour inspection thereafter. Check the screen for distortion or openings in the strainer. Replace for either of
these conditions. Clean screen assembly in solvent and dry with compressed air. Damaged strainer O-rings
should be replaced. To install the screen assembly, place the gasket on the screen assembly and install the
assembly in the throttle body and tighten to 35-40 inch-pounds torque.
8A-27. ADJUSTMENT OF IDLE SPEED AND MIXTURE.
a.
Start the engine and warm up in the usual manner until oil and cylinder head temperatures are
normal. The electric fuel pump must be "ON" for b, c, d and e below.
b.
Check magnetos. If the "mag-drop" is normal, proceed with idle adjustment.
c.
Set throttle stop screw so that the engine idles at 550-600 RPM. If the RPM changes appreciably
after making the mixture adjustment during the succeeding steps, readjust the idle speed to the desired
RPM.
d.
When the idling speed has been stabilized, move the cockpit mixture control with a smooth,
steady pull toward the "Idle Cut-Off" position and observe the tachometer for any change during the
leaning process. Caution must be exercised to return the mixture control to the "Full Rich" position before
the RPM can drop to a point where the engine cuts out. An increase of more than 50 RPM while "leaning
out" indicates an excessively rich idle mixture. An immediate decrease in RPM (if not preceded by a
momentary increase) indicates the idle mixture is too lean.
e.
If the above indicates that the idle adjustment is too rich or too lean, turn the idle mixture
adjustment in the direction required for correction, and check this new position by repeating the above
procedure. Make additional adjustments as necessary until a check results in a momentary pick-up of
approximately 50 RPM. Each time the adjustment is changed, the engine should be run up to 2000 RPM to
clear the engine before proceeding with the RPM check. Make final adjustment of the idle speed adjustment
to obtain the desired idling RPM with closed throttle. The above method aims at a setting that will obtain
maximum RPM with minimum manifold pressure. In case the setting does not remain stable, check the idle
linkage; any looseness in this linkage would cause erratic idling. In all cases, allowance should be made for
the effect of weather conditions and field altitude upon idling adjustment.
Added: 8/31/76
POWER PLANT - LYCOMING
1K20