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Cummins/Onan 5.0GenSet ES 1348 — Setting Main Adjustment Screw for Carburetor

For the Cummins/Onan 5.0GenSet ES 1348.

Applies to: Cummins Onan 5 0Genset Es 1348

Before you start

  • To avoid personal injury, use extreme caution when making adjustments while the engine is running. Do not touch hot exhaust pipes or moving parts
  • do not wear loose clothing that may be caught in moving parts.
  • When determining fuel mixture settings, never force the fuel mixture adjustment needles against their seats. Forcing will damage the needles and seats and make accurate adjustment impossible.

Procedure

  1. Start the alternator and allow it to warm up for at least 10 minutes before making any adjustments.
  2. Remove all loads and connect a tachometer or frequency meter to the alternator.
  3. Turn the main adjustment screw IN (clockwise-lean) until set RPM and frequency drops.
  4. Turn the main adjustment screw OUT (counter-clockwise-rich) until set RPM and frequency drops again.
  5. Over a narrow range between these two settings, the alternator RPM and frequency will remain at its highest. Turn the main adjustment screw slightly OUT from the midpoint of these two settings.

Tools required

  • Tachometer or frequency meter

Source: manual:919-0120 Onan P-Series (spec J) Portable Genset Operators manual (12-1981).pdf. Figures and steps are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.