Generac · Portable generator · GP18000EFI COsense 50ST

GP18000EFI COsense 50ST

Name: Generac GP18000EFI COsense 50ST
Brand: Generac
Price: 4399 USD

GP18000EFI COsense 50ST delivers up to 18,000 running watts and 22,500 starting watts from a portable gasoline system.

18,000W ratedPortable generatorGasolineListed available

Check Generac price Official listed price $4,399.00

Portable Generator, 18000 | EFI | Electric Start with COsense | 50ST — Product image · Generac

Product decision summary

Researched by Andrew Petla · reviewed under the FMG editorial standard · Sep 15, 2026

Trace the evidence · not a hands-on review

Bottom line

Best for specific needs for high-demand home backup & large tools and equipment.

Best for: High-demand home backup & Large tools and equipment

Running output

18,000W

Fuel / power

Gasoline

Weight

442.8 lb

Strongest reasons

GP18000EFI COsense 50ST delivers up to 18,000 running watts and 22,500 starting watts from a portable gasoline system.
Running output is higher than 98% of its class.
Peak output is higher than 97% of its class.

Know before buying

At 442.8 lb, this is a wheeled or placed unit—not a carry-style generator.

Scores at a glance

Class score

Starter fit

Best for specific needs among 144 high output portable generators.

Possible fit

See score details Personalize in 60 sec

Best current buying route

$4,399

MSRP at Generac

The only verified seller destination. Its listed price is known, but shipping and delivered cost still need confirmation. Confirm price, stock, shipping, and the exact model on the seller’s site.

Check price & availability

Affiliate links may earn us a commission at no added cost to you. Disclosure

Never run a fuel-burning generator in a home, garage, shed, or other enclosed or partly enclosed space.

Price intelligence Evidence ledger Accessories & manuals

Key specifications

The numbers that drive the decision.

Published values stay labeled, and every usable metric includes class context. Missing data is shown instead of estimated.

Open complete specifications

Specification	This model	Class median	Context
Running output	18,000WHigher than 98% of its class	9,100W	Higher than 98% of its class
Peak / starting output	22,500WHigher than 97% of its class	11,350W	Higher than 97% of its class
Published runtime	9 hrLonger than 16% of its class	11 hr	Longer than 16% of its class
Product weight	443 lbLighter than 4% of its class	216 lb	Lighter than 4% of its class
Published sound level	Not publishedNo class comparison available	Not enough class data	No class comparison available
Fuel / power source	GasolinePortable generator	Not applicable	Portable generator
Best current price	$4,399MSRP at Generac	Prices change	MSRP at Generac

Class comparisons use 144 high output portable generators. Runtime figures can use different loads, fuels, or test conditions; confirm the model manual before planning fuel or battery duration.

Product gallery & complete specifications Official imagery, full spec tables, use cases, and source linksView details

Infographic gallery

Output, stored energy, charging, and portability.

Scroll sideways to explore →

01 · Usable output

18,000W rated output

Gasoline18,000W / 22,500W

The comparison uses Generac’s published rated and peak, surge, or maximum output figures.

02 · Energy & runtime

Energy source

Gasoline

Published runtime guidance

9 hours at 50% load on the primary listed fuel

03 · Size & construction

442.8 lb

Listed weight

39.5 × 30.9 × 36.5 in

Dimensions

Battery or engine: 816cc OHV with EFI
Warranty: See the official Generac warranty document for this model

04 · Charging & continuity

Charging or integration

Fueling and starting per Generac instructions; manual transfer equipment sold separately

Backup transfer

Not an automatic standby system; approved manual transfer equipment is required for home connection

Noise

No official dBA figure listed on the model page

Official product gallery

Product views and factory feature graphics.

The current official image set for GP18000EFI COsense 50ST includes product views, connection diagrams, feature explanations, and compatible system configurations where Generac publishes them.

GP18000EFI COsense 50ST official Generac image 1 — Published by Generac · image 1 of 8

GP18000EFI COsense 50ST official Generac image 2 — Published by Generac · image 2 of 8

GP18000EFI COsense 50ST official Generac image 3 — Published by Generac · image 3 of 8

GP18000EFI COsense 50ST official Generac image 4 — Published by Generac · image 4 of 8

GP18000EFI COsense 50ST official Generac image 5 — Published by Generac · image 5 of 8

GP18000EFI COsense 50ST official Generac image 6 — Published by Generac · image 6 of 8

GP18000EFI COsense 50ST official Generac image 7 — Published by Generac · image 7 of 8

GP18000EFI COsense 50ST official Generac image 8 — Published by Generac · image 8 of 8

Complete specifications

The complete factory data available for comparison.

These pages retain Generac's model-specific output, charging, battery, port, continuity, dimensions, environmental, engine, fuel, app-control, and warranty fields where published.

Run combustion generators outdoors only. Keep the generator at least 20 feet from occupied buildings with exhaust directed away from doors, windows, and vents.

Comparison summary

Gasoline output: 18,000W running / 22,500W starting or surge
Energy source: Gasoline
Dimensions: 39.5 × 30.9 × 36.5 in
Listed weight: 442.8 lb
Price and availability: $4,399.00 official MSRP; check current availability from Generac

Factory output & connection specifications

Generac model number: G0089170
Gasoline output: 18,000W running / 22,500W starting
Fuel Tank Capacity (gal): 14.2
Fuel Tank Capacity (l): 54
Oil Capacity (qt): 2.2
Oil Capacity (l): 2.1
Running Watts (W): 18,000
Starting Watts: 22,500
WiFi Factory Installed: No

Factory charging & battery specifications

Battery Included: Yes
Battery Type: Group U1
Battery Size: 120/240 VAC

Factory engine, fuel & runtime specifications

Fuel Type: Gaseous
Starting Method: Electric Start
Engine Type: OHV
Engine Size (Liters): 816cc
Run Time @@ 50% Load (hr): 9

Factory dimensions & operating specifications

Dimensions: 39.5 × 30.9 × 36.5 in
Listed weight: 442.8 lb
Wheel Kit Included: No
Length (in): 39.5
Length (cm): 100.3
Width (in): 30.9
Width (cm): 78.5
Length (in): 36.5
Length (cm): 92.8
Weight (kg): 200.9
Weight (lb): 442.8

Additional factory specifications

Base model / SKU: 8917_
Official MSRP: $4,399.00
Extension Cord Included: No
Parallel Capable: No
Transfer Switch Included: No
Non Wi-Fi / NFPA 110 Capable: No
Mobile Link: No
Quiet Test: No
Controller Type: N/A
Enclosure: N/A

Official feature details

System capability

GP18000EFI COsense 50ST delivers up to 18,000 running watts and 22,500 starting watts from a portable gasoline system.

Power delivery

From emergency home backup to DIY projects to the jobsite, the Generac GP18000EFI portable generator provides high wattage, dependable portable power.

Safety and controls

Equipped with an 816cc engine with Electronic Fuel Injection, the GP18000EFI delivers power efficiently, providing up to 9 hours of runtime at 50% load.

Runtime and fueling

TruePower™ Technology safely powers sensitive electronics, appliances and tools while onboard COsense® Technology provides powerful protection against hazardous carbon monoxide.

Portability detail

The GP18000EFI also features electric start (battery included), low-oil shutdown protection, circuit breaker protected outlets and an hour meter with maintenance resets.

Connection options

The included never-flat wheel kit and available lifting eye accessory make transportation easy around the home or jobsite.

Ownership note

Featuring COsense® Technology: STOPS.

Additional manufacturer note

Powerful protection against hazardous carbon monoxide.

Best-fit uses

High-demand home backup
Large tools and equipment
Emergency power
Professional jobsites

Standout features

18,000W maximum rated output
22,500W maximum starting or surge output
Gasoline
Portable generator

Match capacity and output to your actual loads.

Use the independent calculator before choosing a battery system or generator.

Check my power plan

Sources: Generac GP18000EFI COsense 50ST Generac products Official manualVerified September 15, 2026

Price & Availability

Compare the whole buying route.

The lowest sticker price is not always the best offer. We rank exact-model seller pages using price, stock, shipping, freshness, returns, and warranty details—then show what is still unknown.

Price and delivered cost

Shipping is included only when the seller publishes a usable amount.

Stock and freshness

Current, low-stock, preorder, and stale records are scored differently.

Purchase protections

Published return and warranty terms improve evidence confidence.

Affiliate-neutral ranking

Commission status is recorded but never adds ranking points.

Watch this model

Save it to your shortlist to retain the current price snapshot and turn price and safety watches on or off.

Best current buying route

Generac GP18000EFI COsense 50ST

Review soon

MSRP

$4,399

at Generac · Verify stock

Verify offer

Seller options

1 with price

Offer rank

57/100

Relative to listed sellers

Data confidence

55%

4 open fields

Delivered totals

0/1

Shipping included

The only verified seller destination. Its listed price is known, but shipping and delivered cost still need confirmation.

Seller data checked Sep 15, 2026.

Shipping not yet verified.

Open fields: confirmed stock, delivered cost, return window, warranty term.

Prices, local stock, shipping, taxes, installation, and seller terms can change. Confirm the exact model and final checkout total before buying. Affiliate disclosure.

Seller comparison

Every verified exact-model destination.

Browse all priced models

One exact-model seller destination is currently verified. We show the unknown fields so a single listing is never presented as a broad market comparison.

Seller

Price

Stock & shipping

Buyer protection

Confidence

Action

Generac

Best overallLowest listed

$4,399

Final total at checkout

Verify stock

Shipping not yet verified

Returns not verified

Warranty not verified

55% complete

Checked Sep 15, 2026

Verify seller

Generac

Best overallLowest listed

Review soon

$4,399

Final total at checkout

Availability: Verify stock
Shipping: Shipping not yet verified
Returns: Not verified
Warranty: Not verified

Verify seller

55% data confidence · checked Sep 15, 2026

Price history

A durable record, starting with verified snapshots.

We preserve each dated seller observation instead of replacing the old number. Trends use the lowest verified listed price on each observation date—not an estimated market price.

Generac

$4,399 · Verify stock

Verify offer

Ownership

What living with it looks like.

Ownership requires a safe fuel plan, hour-based engine service, correct storage, and confidence that parts and support are accessible.

Ownership rule

Use the exact Generac GP18000EFI COsense 50ST manual for maintenance intervals, fluids, storage limits, and warranty requirements. Similar models are not interchangeable.

Open owner’s manual Manufacturer support

Published warranty

See the official Generac warranty document for this model

Coverage can vary by use, seller, and region. Confirm eligibility and exclusions before purchase.

Service information

2 official resources

An owner or operator manual is linked below for exact service intervals.

Routine upkeep

Engine service required

Oil, filters, spark plug, fuel system, and starting battery needs vary by model and hours used.

Handling & storage

442.8 lb · Gasoline

Plan a wheeled route, stable storage position, and help for steps or vehicle loading.

Practical care plan

From delivery to long-term readiness

1
Day one
Register and record the exact unit
Save the receipt, serial number, seller, warranty terms, and model-specific manual before packaging is discarded.
2
Before first load
Complete setup and break-in correctly
Add the specified oil, inspect the fuel system, position the generator outdoors, and follow the exact break-in and first-service instructions in the manual.
3
Before every use
Check the safety-critical basics
Check oil level, leaks, cords, outlets, grounding instructions, CO-safe placement, and the transfer equipment needed for any building connection.
4
By hours and season
Log service and keep it outage-ready
Track running hours and perform oil, filter, spark-plug, fuel-system, and starting-battery service at the intervals published for this exact model.

Before you buy

Five ownership questions to settle first

Confirm that See the official Generac warranty document for this model applies to your seller, region, and intended use.
Open the official manual for GP18000EFI COsense 50ST and review setup, service intervals, warnings, and storage requirements.
Verify access to Generac parts, authorized service, and a practical return path in your area.
Plan approved fuel storage, outdoor operating clearance, weather protection, and safe refueling.
Plan how the 442.8 lb unit will move over steps, gravel, and door thresholds.

Manuals and compatible accessories Compare seller protections

Evidence

See the proof behind the conclusion.

We separate sourced facts, reproducible calculations, editorial judgments, and missing evidence. That makes every important claim easier to inspect—and harder to overstate.

Published-data coverage

88%documented

7 of 8 relevant evidence fields are documented for this model.

Source-backed editorial analysis—not a hands-on or laboratory test.

Read our evidence standard Explore original market research

Source record

3 traceable sources

Last reviewed Sep 15, 2026

Hands-on testing

Checking ledger…

No manufacturer data is presented as an independent test

Verified owners

Checking reports…

Percentages stay hidden until the sample qualifies

CPSC screening

No model-text match

39 generator recall records screened

88%

Documented fields

Traceable sources

Reproducible calculations

Open evidence gaps

Original calculation

Published surge reserve

4,500W

22,500W peak − 18,000W running

25% above rated running output. This is arithmetic headroom, not a promise that every motor load will start.

Original calculation

Rated power density

40.65 running W/lb

18,000W ÷ 442.8 lb

A catalog-derived portability ratio. It does not account for handles, wheels, shape, or how the weight feels in use.

Original calculation

Listed dollars per running kW

$244.39/kW

$4,399 ÷ 18 running kW

A point-in-time catalog value ratio. It excludes tax, shipping, accessories, fuel, service, and battery expansion costs.

Original calculation

Strongest class-relative spec

98th percentile

Running output: 18,000W ranked within 144 high output portable generators

Higher than 98% of its class

Claim-by-claim evidence ledger

Evidence type	Claim	Basis	Trace
Published factSource-backed	18,000W running and 22,500W peak output are recorded for this model.	Model-specific output fields in the catalog.	Official model source
Published factSource-backed	Gasoline power and 442.8 lb product weight are recorded.	Published configuration and dimensional data.	Official model source
Original calculationReproducible	Published surge reserve: 4,500W.	22,500W peak − 18,000W running	Calculation standard
Original calculationReproducible	Rated power density: 40.65 running W/lb.	18,000W ÷ 442.8 lb	Calculation standard
Original calculationReproducible	Listed dollars per running kW: $244.39/kW.	$4,399 ÷ 18 running kW	Calculation standard
Editorial judgmentEditorial	Best for specific needs for high-demand home backup & large tools and equipment.	Class score 50/100, declared best use, comparative specifications, and explicit buying cautions.	Inspect the score
Editorial judgmentEditorial	At 442.8 lb, this is a wheeled or placed unit—not a carry-style generator.	Editorial risk check based on product category, weight, output, price availability, and missing fields.	Judgment standard
Open evidence gapCaution	Sound level is not sufficiently documented in the current record.	The field remains unknown rather than being inferred from a related model or marketing language.	Not available

Source ledger

Official model source Primary specifications, product identity, and published configuration.Owner’s or operator’s manual Operating, safety, maintenance, and troubleshooting instructions for GP18000EFI COsense 50ST.CPSC recall search Model-text screening against 39 generator recall records; checked 2026-09-16T02:08:27.514Z.

What this evidence cannot prove

No Find My Generator hands-on test, instrumented load test, teardown, or long-term ownership trial is claimed for this page.
Manufacturer specifications may use different fuels, loads, test distances, temperatures, or operating modes. Cross-brand comparisons inherit those differences.
The listed price is a dated snapshot and may not equal the current delivered price.
Sound level is missing and receives no invented or estimated value.

Deeper analysis

Open the details you need

The key decision is above. These supporting scorecards, owner signals, and evidence notes stay out of the way until you want to inspect them.

Fit and score detailsSee the class benchmarks and personalize the fit score for your needs.

Find My Generator score

50/ 100

Best for specific needs

Compared with 144 high output portable generators in the current catalog.

Power98

Running and peak output versus the class

Endurance16

Longest published runtime figure

Portability4

Lower weight scores higher

Fuel flexibility55

Single-fuel operation

Value11

Output or stored energy per listed dollar

Class comparison

See what each spec really means.

A number is more useful with context. Each row shows this model beside its class median and translates the difference into a percentile.

SpecificationThis modelClass medianClass standing

Running output

Higher than 98% of its class

This model · 18,000W

Median · 9,100W

Higher than 98% of its class

Peak output

Higher than 97% of its class

This model · 22,500W

Median · 11,350W

Higher than 97% of its class

Published runtime

Longer than 16% of its class

This model · 9 hr

Median · 11 hr

Longer than 16% of its class

Product weight

Lighter than 4% of its class

This model · 443 lb

Median · 216 lb

Lighter than 4% of its class

How the score works: Scores use published specs and are relative to comparable products in this catalog. Missing specs are excluded and remaining weights are normalized. Runtime is the longest manufacturer-published figure and may use a different load or fuel than another model.

Size a generator for your own appliances

Starter Fit Score

59/ 100

Possible fit

For a 3,000W target and a $1,500 budget.

Above your selected budget

Why it scored this way

A score you can inspect and change.

This personal score is separate from the model’s class score. It measures fit against your priorities and gives neutral partial credit when price or noise data is missing.

Power fit

23.2/35

Clears your 3,000W running target.

Budget fit

4/20

$2,899 above your selected budget.

Fuel fit

15/15

Gasoline works with your flexible fuel preference.

Portability

2/10

442.8 lb against your medium portability priority.

Noise fit

6.5/10

Noise is not published; quietness gets a neutral score.

Use-case fit

8.5/10

Home-backup fit rewards adequate output and fuel flexibility.

Tune my profile

Testing, reviews and evidenceCheck hands-on testing status, owner reliability signals, sources, and data confidence.

Checking the hands-on test ledger…

Testing protocol

The methods behind every result.

This category-specific protocol defines the questions, equipment, conditions, outputs, and safety gates required for this exact model. Published specifications stay visibly separate from hands-on measurements.

Open the hands-on test ledger Read the full test protocol Download measurement worksheet

Manufacturer-published baselines

Rated running output

18,000W

Published

Peak / starting output

22,500W

Published

Product weight

442.8 lb

Published

Published sound level

Pending

How consistently does the unit start under documented conditions?

Follow the manual exactly and record three ambient-temperature starts plus three heat-soaked restarts. Report attempts, elapsed time, start method, battery state, and any intervention.

Attempts per startStart timeAmbient temperatureStart method

Controlled conditions

Record the exact model, serial number, firmware, sample source, and test date before any measurement.
Log ambient temperature, humidity, elevation, wind, surface, and background sound for every test block.
Record instrument model, range, accuracy, and most recent calibration or verification date.
Repeat timing, starting, and sound measurements three times when conditions allow; publish every valid run.
Keep original notes, load logs, meter exports, photos, and any excluded-run explanation with the result.

Required equipment class

Rated resistive or programmable load bank
True-RMS power, voltage, and frequency logger
Calibrated Class 1 or Class 2 sound-level meter
Approved fuel-measurement equipment and fire protection
Weather meter, timer, tachometer, and non-contact thermometer

Safety gate

Operate fuel-burning equipment outdoors only, far from occupied structures, openings, and ignition hazards, with working carbon-monoxide monitoring for personnel.

Testing is for qualified personnel using correctly rated load equipment and the manufacturer’s required grounding, bonding, clearance, and protective-device instructions.

Never connect a generator directly to building wiring or bypass overload, temperature, battery, GFCI, or carbon-monoxide shutdown protection.

Stop a run for unstable voltage or frequency, overheating, fuel or electrolyte leakage, abnormal sound, damaged wiring, or any manufacturer fault indication.

Badge rule: this product receives no “FMG Tested” label or score benefit until a real unit, instruments, conditions, valid runs, raw records, and limitations are documented under the public protocol.

Verified owner reliability

What happens after the honeymoon period?

Long-term reports from confirmed owners show starting, maintenance, failure, support, and recommendation outcomes for the Generac GP18000EFI COsense 50ST.

See how ownership is verified

Verified owners only

Be the first confirmed owner to report back.

Checking reports…

Reliability percentages stay hidden until at least 5 ownership-verified reports are published for this exact model — 5 more needed.

Ownership checked

Purchase or registration evidence is reviewed privately.

Time in service

Reports separate new ownership from 12+ month experience.

Failures documented

Repairs and maintenance are captured, not buried in a star.

Reports stay private while ownership and model details are checked. Contact information is never shown publicly.

Data trust & safety

Fresh specifications. Visible recall checks.

We show when this record was verified, where its specifications came from, and whether its model number appears in the official CPSC generator-recall dataset.

Review soon

Specification freshness

Last verified: Sep 15, 2026
Review target: Oct 15, 2026
Primary source: Manufacturer / official listing

Prices can change faster than technical specifications. Always confirm the current price, exact model number, and manual before purchase.

CPSC model screening

No model-number match found

39 records checked

The Generac GP18000EFI COsense 50ST model text did not match the generator recall records in our current CPSC snapshot. This is a screening result, not a guarantee or safety certification. Recalls can be serial-number specific, newly published, or use a different product description.

Search CPSC directly Dataset checked Sep 16, 2026

Research owner

Andrew Petla

Founder & lead researcher

Editorial sign-off

Find My Generator Editorial Review

Accountable editor: Andrew Petla

Review scope: exact model identity, published specifications, calculation inputs, source quality, safety language, and affiliate independence. This is an internal editorial review, not third-party engineering, electrical, or safety certification. Hands-on testing is claimed only when a complete test record is published.Request a correction.

Read the full data methodology

GP18000EFI COsense 50ST

Best for specific needs for high-demand home backup & large tools and equipment.

The numbers that drive the decision.

Output, stored energy, charging, and portability.

Product views and factory feature graphics.

The complete factory data available for comparison.

Comparison summary

Factory output & connection specifications

Factory charging & battery specifications

Factory engine, fuel & runtime specifications

Factory dimensions & operating specifications

Additional factory specifications

Official feature details

Match capacity and output to your actual loads.

Compare the whole buying route.

Generac GP18000EFI COsense 50ST

Every verified exact-model destination.

A durable record, starting with verified snapshots.

What living with it looks like.

From delivery to long-term readiness

Register and record the exact unit

Complete setup and break-in correctly

Check the safety-critical basics

Log service and keep it outage-ready

Five ownership questions to settle first

See the proof behind the conclusion.

Accessories, manuals, and documents.

Match by model and connection.

Generator power cord or inlet connection

Parallel kit

Maintenance kit and service parts

Storage cover or approved running shelter

Official product materials.

Open the details you need

See what each spec really means.

A score you can inspect and change.

Power fit

Budget fit

Fuel fit

Portability

Noise fit

Use-case fit

The methods behind every result.

Questions the measurements must answer.

Continuous output & regulation

Starting-load response

Fuel use & runtime

Sound profile

Cold & hot starting

What happens after the honeymoon period?

Be the first confirmed owner to report back.

Ownership checked

Time in service

Failures documented

Fresh specifications. Visible recall checks.

Specification freshness

No model-number match found

Keep the decision moving.

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