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Home›Repair guides›Cummins/Onan›Fuel Metering Valve Adjustment Procedure

Cummins/Onan 11RMY / 8.5RMY — Fuel Metering Valve Adjustment Procedure

Adjustments · fuel metering valve / oxygen sensor

For the Cummins/Onan 11RMY / 8.5RMY, from the Cummins/Onan service manual.

Applies to: Cummins/Onan 11RMY, Cummins/Onan 8.5RMY, Kohler CH20 engine, Kohler CH25 engine

Before you start

  • Disconnect battery cables before working on generator set (negative lead first, reconnect last)
  • Hot engine and exhaust system can cause severe injury or death; allow to cool before servicing

Procedure

  1. Place generator set master switch OFF
  2. Disconnect power to battery charger, if equipped
  3. Disconnect engine starting battery, negative lead first
  4. Remove oxygen sensor plug from exhaust manifold
  5. Install oxygen sensor in exhaust manifold where plug was removed
  6. Check master switch is OFF, reconnect battery negative lead last
  7. Place controller master switch to RUN to start generator set
  8. Allow generator set to run until normal operating temperature
  9. Apply 90-100% of rated load
  10. Connect DVM leads between oxygen sensor lead and ground, measure output voltage
  11. Adjust fuel metering valve to obtain 0.5 vdc -0.3 output from oxygen sensor
  12. Remove load, allow generator set to run unloaded 5-10 minutes to cool
  13. Place master switch OFF, disconnect battery negative lead first
  14. Disconnect DVM leads, allow exhaust system to cool, remove oxygen sensor
  15. Apply antiseize compound to exhaust plug, reinstall plug, reconnect battery negative last

Tools required

  • digital volt meter (DVM) Amazon
  • oxygen sensor (A-345052) Amazon
  • load bank capable of rated kW for the fuel being used Amazon

Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.

Specs & values

  • 0.5 vdc -0.3 output from oxygen sensor at 90-100% rated load

Full service-parts list: Cummins/Onan 11RMY →, Cummins/Onan 8.5RMY →

Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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