Cummins/Onan QSL9 Engine
The Cummins/Onan QSL9 is a 8.9 L 6-cylinder turbocharged and charge-air cooled engine rated at 1470 rpm, producing up to 299 kW. It powers generator sets from Cummins/Onan, including the CFP9E-F40, CFP9E-F50, CFP9EVS-F40 and CFP9EVS-F50. It holds 24 L (6.3 gal) of oil and 2.9 L (0.8 gal) of coolant.
Also known as: Cummins QSL9
Part of the Cummins/Onan QSL9 engine family — 12 variants share parts & fitment.
Engine specifications
| Oil capacity | 24.0 L |
|---|
| Coolant capacity | 2.9 L |
|---|
| Displacement | 8.9 L |
|---|
| Cylinders | 6 |
|---|
| Aspiration | Turbocharged and Charge-Air Cooled |
|---|
| Rated speed | 1470 rpm |
|---|
| Gross power | 299 kW |
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Troubleshooting
1Fault codes
| Code | Meaning |
|---|
| 251 | Unknown J1939 Fault |
Fault codes and symptom→remedy steps extracted from this engine’s service/owner documentation; verify against the official manual before servicing.
Maintenance schedule
Pooled from every document that names this exact engine — confirm the interval and part number against your unit's serial number.
Service specifications
4| Type | Item | Value | Unit | Condition |
|---|
| Other | Pressure sensing line nominal size inside diameter | 1/2 | in. (12.7 mm) | connected between the transducer (located under the FPDP) and the pump discharge flange and the discharge check valve |
| Pressure | Cooling loop cooling water pressure limit | 270 | psi | installations where the discharge pressure is greater than 270 psi (pressure reducing valve required upstream of the cooling loop) |
| Pressure | Discharge set point pressure / maximum control pressure | 100/110, 170/175, or 240/250 | psi | set by the factory and not adjustable; specify at time of order |
| Pressure | VSPLC set point range | 100 to 400 | psi | |
Extracted from the manufacturer documentation linked to this model. Values are copied as printed; confirm against your unit's manual and serial number.
Parts cataloged across the Cummins/Onan QSL9 family
67| Part # | Description | Category |
|---|
| 4021518 | Alternator Manual | Alternator |
| 431PSL6206 | Marathon Magna Plus / 431PSL6206 | Alternator |
| PI144D1 | Alternator Model | Alternator |
| UC274C | Alternator Model | Alternator |
| UC274K | Alternator Model | Alternator |
| 0518-0548-15 | Clamp | Clamp |
| 0518-0548-22 | Clamp | Clamp |
| 0518-0548-29 | Clamp | Clamp |
| 0518-0548-35 | Clamp | Clamp |
| A056F113 | Clamp | Clamp |
| QSL9-G2 | Cummins / QSL9-G2 | Engine |
| A052T655 | Gasket | Gasket |
| A047A980 | Heater, Blanket | Heater |
| A045P359 | Hose, DEF | Hose |
| A045P417 | Hose, DEF | Hose |
| A051B439 | Hose, DEF | Hose |
| 1000A | LCD Ammeter | Service part / kit |
| A030X751 | Box | Service part / kit |
| A030Y642 | Hinge | Service part / kit |
| A031A954 | Panel, Enclosure | Service part / kit |
| A034N673 | Grill, Enclosure | Service part / kit |
| A034N943 | Bolt, Carriage | Service part / kit |
| A034P011 | Bolt, Carriage | Service part / kit |
| A034P012 | Washer, Flat | Service part / kit |
| A034P026 | Screw, Hex Flange Head | Service part / kit |
| A034P039 | Nut | Service part / kit |
| A034P108 | Screw, Hex Flange Head | Service part / kit |
| A035H898 | Screw, Hex Head | Service part / kit |
| A035P345 | Lead, Electrical | Service part / kit |
| A041D550 | Header, Door | Service part / kit |
| A041E195 | Panel, Enclosure | Service part / kit |
| A041E396 | Panel, Enclosure | Service part / kit |
| A041E596 | Header, Door | Service part / kit |
| A041E928 | Post, Enclosure | Service part / kit |
| A041M317 | Door, Control | Service part / kit |
| A041S526 | Insulation, Door | Service part / kit |
| A046F214 | Panel, Enclosure | Service part / kit |
| A046F238 | Panel, Enclosure | Service part / kit |
| A047V570 | Panel, Window | Service part / kit |
| A052S411 | Latch | Service part / kit |
| A053J589 | Screw, Hex Head | Service part / kit |
| A053J591 | Screw, Hex Head | Service part / kit |
| A053T433 | Padlock, Attachment | Service part / kit |
| A055G556 | Screw, Socket Head | Service part / kit |
| A056C784 | Latch, Mechanical | Service part / kit |
| A056H470 | Hinge | Service part / kit |
| A056M306 | Bolt, Carriage | Service part / kit |
| A063L015 | Door, Enclosure | Service part / kit |
| A063L064 | Header, Door | Service part / kit |
| A063L069 | Header, Door | Service part / kit |
| A063L072 | Panel, Enclosure | Service part / kit |
| A063L080 | Panel, Enclosure | Service part / kit |
| A064U218 | Cover, Electrical Connector | Service part / kit |
| A072Y708 | Door, Enclosure | Service part / kit |
| A072Y709 | Panel, Enclosure | Service part / kit |
| V2403-M-E3BG | Engine Model | Service part / kit |
| A045J792 | Pump, Doser (See Page 70 for Components) | Pump |
| 0821-0016 | Screw, Locking | Screw |
| 0821-0029 | Screw, Locking | Screw |
| 0821-6002-03 | Screw, Hex Head | Screw |
| 0821-6003-01 | Screw, Hex Head | Screw |
| A030Y648 | Edging, Seal | Seal |
| A047V572 | Seal, Weather | Seal |
| A054S414 | Seal, Door | Seal |
| A054S416 | Seal, Door | Seal |
| A046D072 | Strap, Tank | Strap |
| A049G884 | Tank, DEF Complete (Includes Header and Heated Blanket) (See Page 66 for Components) | Tank |
Parts cataloged across all variants of this engine family — verify the exact part fits your specific variant and serial number before ordering.
Common questions
What is the oil capacity of the Cummins/Onan QSL9?
The Cummins/Onan QSL9 engine has an oil capacity of 24.0 liters.
What is the displacement of the Cummins/Onan QSL9?
The Cummins/Onan QSL9 has a displacement of 8.9 liters with 6 cylinders.
Which generators use the Cummins/Onan QSL9 engine?
The Cummins/Onan QSL9 powers 4 generator set(s), including Cummins/Onan CFP9E-F40, Cummins/Onan CFP9E-F50, Cummins/Onan CFP9EVS-F40, Cummins/Onan CFP9EVS-F50.