G420E/G424E Tier LP Engine Test And Adjustments 86
7. While on the Run Screen adjust the idle mixture
screw on the mixer until a reading of 25-50% is
reached for the FTV Duty Cycle (Figure G10).
8. To make this adjustment you will need to adjust
the nylon screw all the way inward and then back
out the screw ¼ turn.
9. Use the accelerator pedal to increase RPM above
idle momentarily (Rev the engine) then release
the pedal to return to idle RPM. The duty cycle
setting should remain within the adjustment range
(25-50%).
10. To obtain an accurate FTV Duty Cycle reading
when the tamper proof is not installed, place your
thumb over the idle screw port so that no air will
leak past the screw threads.
11. If the FTV Duty Cycle reading is above 50% back
the idle adjustment screw out again and re-check
your duty cycle reading. Continue to do this until
the FTV Duty Cycle reading is within the proper
range (25-50%)
12. Turn the ignition key to the OFF position to shut
down the engine.
13. Install the tamper proof cap on the idle mixture
screw adjustment port so that no further
adjustments can be made (Figure G11).
NOTE
If the FTV Duty Cycle reading is cannot
be adjusted between 25-50%, check for
possible vacuum leaks, manifold leaks or
a faulty mixer.
Figure 10 Figure 11
Idle Mixture
Screw
Tamper Proof
Cap
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