Cummins/Onan — Carburetor Main Adjustment Screw
Adjustments
From a Cummins/Onan operator's manual covering: 1.7PE-1P, 1.7PE-1P/24950J, 2.2PE-1P, 2.2PE-1P/24950J, 2.2PEI-1P, 3.0PL-1P, 3.0PL-3P, 3.2PFI-3P, 3.7PFI-3P, 3.7PP-3P, 5.0PKI-3P, 5.0PN-3E…. Check it applies to your exact model before use.
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Before you start
- Use extreme caution when adjusting while engine is running.
Procedure
- Start alternator and warm up at least 10 minutes.
- Turn main adjustment screw IN (clockwise) until lightly seated.
- Back out 1-1/4 to 1-1/2 turns.
- Connect tachometer or frequency meter and apply full load.
- Adjust for highest RPM and frequency.
- Turn main adjustment screw slightly OUT from midpoint.
Tools required
- Tachometer or frequency meter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Initial setting 1-1/4 to 1-1/2 turns out.
Source: Cummins/Onan operator's 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.