Engine System
27
Service Manual – PBU Propane Floor Burnisher
Low Idle Mixture
1 Starting with a warm engine running at high idle,
bring the throttle selector to the Slow position
2 Check the voltage of the oxygen sensor It should
be between 35 and 50 mV (0 035 - 0 050 V)
3 If the oxygen sensor voltage is out of range, turn
the Low Idle Mixture screw with increments of
1/4 to 1/2 turn at a time, and waiting for about
30 seconds between increments for the change to
take effect
• Low Voltage: Turn the screw clockwise This
will increase (richen) the fuel mixture
• High Voltage: Turn the screw counterclockwise
This will decrease (lean) the fuel mixture
4 After the mixture has been changed, it is likely
that the low-idle speed will change Readjust the
High Idle (Full Load) Mixture
1 Starting with a warm engine running at high idle, load the machine by operating the burnishing pad on
a floor surface.
2 While the machine is loaded, observe the voltage
reading from the oxygen sensor The voltmeter
reading should be between 50 and 60 mV (0 050
to 0 060 V)
3 If the oxygen sensor voltage is out of range, turn
the high limit fuel adjustment screw (triangular
head screw) in 1/4-turn increments
• Loosen the setscrew on the back of the outlet
that locks the adjustment screw
• Low Voltage: Turn the screw counterclockwise
This will increase (richen) the fuel mixture
• High Voltage: Turn the screw clockwise This
will decrease (lean) the fuel mixture
4 After each screw-turn increment, recheck the
oxygen sensor voltage with the machine operating
under load
5 Retighten the locking setscrew that prevents the adjustment from turning
6 After the mixture has been changed, it is likely that the high-idle speed will change Readjust the
7 Replace both of the anti-tampering caps on the regulator
Low Idle
Screw
Small
Setscrew
High Idle
Screw
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