Generac 91401256S / Bsc 556 — Stepper Motor/Throttle Linkage Set-up and Adjustment
Adjustments · Generac stepper motor electronic governor
For the Generac 91401256S / Bsc 556, from the Generac service manual.
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Before you start
- Frequency and direction switches are integrated only at engine start.
Procedure
- Determine direction stepper motor must rotate to open throttle to full fuel.
- Adjust rod length so stepper motor is at full rotation when throttle is wide open; tighten jam nuts.
- Ensure linkage moves freely and does not bind.
- Set GAIN, DROOP, and STABILITY pots to midpoint.
- Set frequency switch to OFF for 60 Hz or ON for 50 Hz.
- Set direction switch OFF for counterclockwise opening or ON for clockwise opening.
- Start engine and adjust gain pot to stabilize engine speed.
- Apply 25-50% load; if unstable, reduce gain until stable.
- Adjust droop pot so engine speed recovers to pre-selected speed.
- Observe performance when loads applied and removed; adjust stability as needed.
Specs & values
- frequency switch OFF = 60 Hz, ON = 50 Hz
Source: Generac 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.