Cummins/Onan — Magnetic Speed Pickup Unit (MPU) Installation
Adjustments · MPU / flywheel ring gear
From a Cummins/Onan service manual covering: QSX15, QSX15-G8, QSX15-G9. Check it applies to your exact model before use.
Applies to: Cummins/Onan DFE, Cummins/Onan DFEJ, Cummins/Onan DFEK, Cummins/Onan QSx15, Cummins/Onan QSX15-G9 engine
Before you start
- Do not use fan blade to bar over the engine; that can damage blades and cause property damage and personal injury.
Procedure
- Measure the resistance of the MPU; replace if not between 1,000 ohms and 1,050 ohms.
- With the MPU removed, bar the engine until a flywheel gear tooth lines up in the center of the mounting hole.
- Thread the sensor in gently by hand until it just touches the gear tooth.
- Back it out 1/4 turn and set the locknut.
- After adjustment, verify output voltage of the MPU is correct.
Tools required
- Ohmmeter Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- MPU resistance: 1,000 to 1,050 ohms
- Back out 1/4 turn after contact
- Replace MPU if output voltage at cranking speed is less than 1.5 VAC
Full service-parts list: Cummins/Onan DFE →, Cummins/Onan DFEJ →, Cummins/Onan DFEK →, Cummins/Onan QSx15 →
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.