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Cummins Onan 4MKY Specs (Power | Fuel Consumption)

Written by Ernie Lo in Specs Last Updated August 18, 2026

The Cummins Onan 4MKY generator is listed with standby output of 4000 kW, Gasoline fuel, 60 Hz operation, 120 V, 220 V output, Single phase, and rated current of 33.3 / 16.4 A.

Cummins Onan Generator Specifications

Generator • Gasoline • 60 Hz • Single phase

Standby power: 4000 kWVoltage options: 120 V, 220 VRated current: 33.3 / 16.4 ADry weight: 185 lb (84 kg)

Key specifications

4000 kW Standby power
Gasoline Fuel
120 V, 220 V Voltage options
Single phase Phase
33.3 / 16.4 A Rated current
185 lb (84 kg) Dry weight
60 Hz Frequency

Useful generator charts

Charts are shown only when this model has enough usable source data.

Fuel consumption by load
How fuel use changes as generator load increases.
No load

0.29 gal/hr

50% load

0.48 gal/hr

100% load

0.71 gal/hr

Power-to-weight
Standby output per 1,000 lb of dry weight versus similar-output Cummins Onan models.
This model

21,599.6 kW

Peer average

55.6 kW

99th percentile
Power output
Low 4,000 kW High 4,000 kW
Standby

4,000 kW

Prime

4,000 kW

Model spec snapshot
Representative numeric specifications from this generator.
4,000 kWStandby
185.19 lbWeight

How the Cummins Onan 4MKY compares

This compares the supplied numeric specification with Cummins Onan generators in the same broad standby-power class where enough comparable data exists.

Standby power
4,000 kW
118% above avg
99th percentile
Dry weight
185 lb
99% below avg
11th percentile
Oil capacity
0.4 gal
99% below avg
8th percentile
Standby power4,000 kW
Low 1,000 kWAverage 1,831.9 kWHigh 3,562 kW

About 118% above the similar-output Cummins Onan average. Around the 99th percentile for this field.

Dry weight185 lb
Low 71 lbAverage 30,152 lbHigh 65,094 lb

About 99% below the similar-output Cummins Onan average. Around the 11th percentile for this field.

Oil capacity0.4 gal
Low 0.28 galAverage 51.88 galHigh 105.14 gal

About 99% below the similar-output Cummins Onan average. Around the 8th percentile for this field.

This model Peer average

Generator information

Manufacturer Cummins Onan
Model 4MKY
Generator type Generator
Fuel Gasoline
Frequency 60 Hz

Electrical output

Standby power 4000 kW
Prime power 4000 kW
Voltage options 120 V, 220 V
Phase Single phase
Rated current 33.3 / 16.4 A

Engine, cooling and controls

Engine model Cummins/Onan Onan
Engine displacement 26 cu in (0.42 L)
Aspiration / cooling OHV 4-stroke
Rated engine speed 3600 rpm
Engine oil capacity 0.29 gal (1.1 L)
Oil capacity 0.4 gal (1.5 L)
Controller A1, Microprocessor Regulated

Physical specifications

Dry weight 185 lb (84 kg)

Battery

Battery cranking 360 / 450 CCA
Battery voltage 12 V
Battery quantity 1

Fuel consumption

Standby 0.29 gal/h (1.1 L/h)
Prime 0.48 gal/h (1.8 L/h) @ 50%; 0.71 gal/h (2.7 L/h) @ 100%
Full load 0.71 gal/h (2.7 L/h) @ 100%; 1.0 gal/h
Half load 0.48 gal/h (1.8 L/h) @ 50%; 0.5 gal/h (1.4 L/h)
No load 0.29 gal/h (1.1 L/h); 0.3 gal/h (0.79 L/h)

Maintenance and service parts

Engine oil Interval: 25 hr; Specification: SAE 10W30

Disclaimer: Specifications should be verified against the official owner’s or service manual and confirmed on the Cummins North America generator website.

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Ernie Lo

Ernie Lo is a qualified web designer and web developer. He works as an IT support technician and website manager at Benleigh Vending, and he also fixes vending machines.

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