Benchmark with Edge [I]: Operation-Maintenance Manual
SECTION 8 – MAINTENANCE
OMM-0145_D • GF-218 • 11/2/2020 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST Page 136 of 213
Lean O
2
Sensor Maintenance Instructions
4. Next, loosen and remove the O
2
sensor and crush washer from the burner plate using a
15/16" open-end wrench.
5. Thoroughly inspect the O
2
sensor. If eroded, the sensor should be replaced. Otherwise
clean the sensor with a fine emery cloth.
6. Reinstall the O
2
sensor and crush washer on the burner plate.
7. Reconnect the sensor lead wire.
8. Reinstall the shroud on the unit.
8.4.1 Air Eductor Air Pump Maintenance – BMK5000 & 6000
Benchmark 5000 and 6000 units contain an Air Eductor assembly, mounted just inside the O
2
Sensor Cover on the unit’s back panel, (see Figure 8-3b, above). It includes an air pump, which
draws an air sample from the combustion chamber past the O
2
Sensor, ensuring its accuracy.
The air pump contains an air pump filter (P/N 87008), which should be inspected-cleaned every
12 months and replaced every 24 months. It is included in the BMK5000 & 6000 24 Month
Maintenance Kits.
Air Pump Maintenance and Troubleshooting Instructions
1. Remove the Air Pump’s plastic air filter cover and clean or replace the air filter (see Figure
8-4, below).
2. If the Air Eductor or the Air Pump is not operating properly, try the following troubleshooting
steps:
a) Check the connector to the Air Pump for corrosion or contamination, clean as
needed.
b) If the Air Pump is not running, check 120 VAC power to the Air Pump. If 120 VAC
power is OK, replace the Air Pump.
c) If the Air Pump is running, check current drawn in series with one power wire. If the
current is within the range of 0.1 to 0.6 amps, the Air Pump is operating properly.
d) Check the signal from current sensor. If it is within the range of 0.20 to 1.20 VDC,
there may be a connector problem or IGST board issue. Check all connectors and
wires first. Try swapping IGST board with known good board before ordering a new
one.
3. Reattach the O
2
Sensor Cover to the unit’s back panel.
Figure 8-4: Air Eductor Assembly – BMK5000 & 6000
GAS SUCTION LINE TO
EXHAUST MANIFOLD
BRACKET
(Hangs on opening in back panel)
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