Littleton, CO Standby Generator Installation & Maintenance — Why Your Generac Won’t Start

Estimated Read Time: 10 minutes

Power outage and your Generac generator won't start? You are not alone, especially in Colorado where sudden storms and cold snaps hit hard. This guide explains the most common causes, quick DIY checks, and safe fixes. If you need help, Fix-it 24/7 handles installation, maintenance, and 24/7 emergency repairs across the Denver Metro. Keep reading for clear steps, costs, and when to call a licensed pro.

Safety First: Quick Checks Before You Troubleshoot

Power equipment deserves respect. Before you touch anything, switch the generator to Off and remove the service disconnect. Let the unit fully stop. If you ever smell gas or see damage, stop and call a professional immediately.

Run these five checks first:

1. Verify utility power and the main breaker position. If utility power is on, confirm your generator is in Auto, not Off.
2. Inspect the generator’s external breaker and the Automatic Transfer Switch (ATS) for tripped breakers. Reset once only.
3. Look for error codes on the controller. Note the exact message for your technician.
4. Confirm fuel: natural gas or propane supply valve open, propane tank not empty, no visible line damage.
5. Listen for the battery click. Weak or silent clicks often point to battery or starter issues.

Local tip: Cold, dry Front Range air and altitude can make borderline batteries and fuel-air mix problems show up faster in winter. A low battery that might start at sea level often fails at 5,280 feet.

The Top 10 Reasons Your Generac Will Not Start

Below are the real-world culprits we see most often in Denver homes, plus safe homeowner actions and when to call us.

1) Battery is weak, dead, or corroded

Symptoms: Rapid clicking, dim display, or nothing at all. Cold snaps drain marginal batteries fast.

What you can do:

• Check and clean battery terminals. Light corrosion can be removed with baking soda and water.
• If you have a basic multimeter, a healthy 12V battery at rest should read around 12.6V.

When to call: If voltage is low after charging or the battery is older than 3 years. We test load capacity and replace with the correct cold-cranking amps for Colorado winters.

2) Unit left in Off or Exercise disabled

Symptoms: Generator never starts during outages or misses the weekly exercise.

What you can do:

• Confirm the control is set to Auto and the schedule is enabled.
• Check if someone turned off the external breaker during yard work or maintenance.

When to call: If the controller shows logic or programming faults. We update firmware and test exercise routines.

3) Tripped breaker or ATS problem

Symptoms: Generator starts but does not power the home, or tries to start and shuts down quickly.

What you can do:

• Check the generator’s breaker and your home’s main panel for trips. Reset once.
• Inspect the ATS for status lights. Do not open the ATS enclosure.

When to call: Any ATS fault or repeated trips. NEC Article 702 governs optional standby systems, and ATS work must be done by a licensed electrician for safety and code compliance.

4) Fuel supply issues on natural gas or propane

Symptoms: Long cranking, starts then stalls, strong fuel smell, or ice on propane regulator in extreme cold.

What you can do:

• Make sure the gas valve is open and the propane tank is not near empty.
• Clear snow and debris from around the regulator and intake louvers.

When to call: If you suspect pressure or regulator issues. We perform load calculations and coordinate with your gas provider. We also confirm line sizing that meets generator demand under load.

5) Clogged air filter or intake restriction

Symptoms: Rich exhaust smell, sputtering, or rough start.

What you can do:

• Inspect and replace the air filter if it is dark or packed with debris.
• Keep 3 feet of clearance around the cabinet for proper airflow.

When to call: If performance does not improve after a fresh filter. We test airflow, fuel trim, and high-altitude adjustments.

6) Spark plug wear or ignition failure

Symptoms: Extended cranking, misfires, or backfiring on start.

What you can do:

• If you are comfortable and it is safe, inspect the spark plug for heavy fouling or a cracked insulator. Replace like for like.

When to call: For persistent misfires. We verify correct gap, ignition coil health, and controller spark timing.

7) Low oil, wrong oil weight, or oil sensor fault

Symptoms: Cranks but does not start, or shuts down with an oil warning.

What you can do:

• Check oil level on a level surface. Top up with the manufacturer-approved weight for current temperatures.

When to call: If warnings persist or oil is dark with metal flake. We diagnose pressure sensors and perform oil analysis.

8) Cold-weather starting challenges at altitude

Symptoms: Hard starting on freezing mornings, especially after long idle periods.

What you can do:

• Use the correct cold-weather kit if recommended for your model. Keep snow away from the enclosure. Do not cover louvers.

When to call: We install approved cold-weather kits and tune for altitude. Denver’s elevation affects air-fuel mix, so a borderline setup may struggle.

9) Controller errors or firmware issues

Symptoms: Random faults, frozen display, or exercise program failures.

What you can do:

• Power cycle the controller per the manual. Record any fault codes.

When to call: We update firmware, verify sensors, and load test. Software issues can mask mechanical problems.

10) Maintenance overdue or improper service

Symptoms: Multiple small faults, dirty filters, varnished fuel residue, or poor voltage under load.

What you can do:

• Review your maintenance log. Most homes need annual service, plus exercise and visual checks monthly.

When to call: If maintenance is behind or you are unsure what was done. Our preventive maintenance includes inspection, cleaning, oil and filter service, battery testing, controller updates, and a full transfer test.

Fast Fixes You Can Try in Minutes

If it is safe and you are comfortable, these steps solve many no-start events:

1. Set the generator to Off. Wait 30 seconds. Return to Auto.
2. Reset a tripped generator breaker once. If it trips again, stop and call.
3. Confirm gas valves are open and propane has adequate level.
4. Replace a clogged air filter and reseat battery cables.
5. Start a manual test run for 5 minutes, then return to Auto.

If the unit still refuses to start, avoid repeated cranking. It can flood the engine and drain the battery.

Prevention: The Maintenance Plan That Works in Colorado

A well-maintained generator is far less likely to fail during a storm. Here is the schedule we recommend for the Denver area:

• Monthly: Visual inspection, clear snow and leaves, check for animal nests, confirm Auto mode, review display for alerts.
• Quarterly: Exercise test under light load, check battery voltage, wipe corrosion, confirm gas valve positions.
• Annually: Full service with oil, filter, spark plug inspection, firmware updates, and a transfer test.

What we include:

• Load analysis to ensure the system is sized correctly and balanced across phases.
• Transfer switch testing for seamless switching.
• Fuel system checks for natural gas or propane, including regulator evaluation.
• Compliance review. We acquire permits and coordinate inspections so your system meets local code. In Denver, standby installs require permits and inspections through Community Planning and Development.

Hard facts to know:

• NEC Article 702 covers optional standby systems, including transfer equipment and wiring methods.
• For most Denver homes, whole home standby systems commonly range from 16 kW to 24 kW, but we always perform a professional load calculation before recommending size.

When To Repair vs Replace

Repair makes sense when:

• The unit is within its expected life and parts are readily available.
• Failures are simple, like a battery or sensor.

Consider replacement when:

• The generator is aging, has repeated major faults, or the required parts are obsolete.
• You have expanded your home’s electrical load and need a larger system.

We service most brands and install standby, portable, and commercial generators. If replacement is right, we handle design, permits, gas line sizing, and inspections, then train you on operation.

Costs and Timelines in the Denver Metro

• Diagnostics: Many issues are identified in the first visit with a controller scan and load test.
• Repairs: Simple fixes like batteries and sensors are typically same-day. Fuel or ATS issues may require coordination with gas utilities or new parts.
• Installation: We manage permits, inspections, pad placement, gas or propane connections, and ATS wiring. Flexible financing can spread costs over time.

Same-day service is often available, and we offer 24/7 emergency response during critical outages.

Why Choose Fix-it 24/7 for Generac Troubleshooting and Service

• Licensed, insured Colorado electricians with deep knowledge of local weather and power infrastructure.
• We handle permit acquisition and inspection coordination for full compliance.
• 24/7 emergency service, $0 service call for repairs, and transparent flat-rate pricing.
• Preventive maintenance programs to keep your system ready when you need it most.

If your generator is not starting, we can be on site fast, diagnose precisely, and get your backup power online with the right fix the first time.

Special Offers for Denver Homeowners

• $0 Service Call for Repairs on standby generator service. Call 303-536-1616 to schedule.
• $69 OFF Any Electrical Service applied to eligible generator electrical work.
• Same-Day Service available in most Denver Metro areas.
• Flexible financing options for new standby generator installation.

Act now to secure priority scheduling during storm season.

What Homeowners Are Saying

"From the initial call to the completed repair, their team was professional, punctual, and respectful. They explained the issue thoroughly and gave an honest quote before doing any work."
–Kelly W., Denver

"Every technician who came to our home was courteous, efficient, and clearly experienced in their trade. The scheduling process was seamless, and they kept us updated every step of the way."
–Elliot L., Generator Service

"We had an emergency late at night, and their team arrived fast and ready to help. They diagnosed the issue quickly and walked us through the repair plan before starting anything at all."
–Sydney W., Emergency Generator Repair

Frequently Asked Questions

Why does my Generac click but not start?

A rapid clicking usually means the battery is weak or corroded. Clean the terminals, confirm tight cables, and test voltage. If it still clicks, the battery may lack cold-cranking amps for winter starts. Call for a load test and replacement.

Do I need a permit to install or replace a standby generator in Denver?

Yes. Standby installs require permits and inspections through Denver Community Planning and Development. We handle permit acquisition, inspections, and code compliance so your project passes on the first visit.

How often should I service my standby generator?

Most homes need annual service plus a monthly visual check and weekly or biweekly exercise. Annual service includes oil, filter, battery testing, firmware updates, and a full transfer test under load.

Does altitude affect generator starting?

Yes. At 5,280 feet, air density is lower and can affect fuel-air mix and cold starts. Proper tuning, clean filters, and cold-weather kits help. We set up your unit for altitude and seasonal conditions.

What size generator do I need for whole home coverage?

Many Denver homes use 16 kW to 24 kW systems, but your exact size depends on a professional load calculation. We measure starting currents for HVAC and other large loads before recommending a generator.

Final Takeaway

If your Generac generator will not start, the fix is often straightforward once you check battery health, fuel supply, filters, and controller settings. For Denver homeowners, altitude and winter conditions add unique challenges. When you are ready, our licensed team can diagnose and repair fast, or design a code-compliant upgrade sized for your home.

Call to Schedule

Call 303-536-1616 or visit https://fixmyhome.com/ to book same-day service. Mention $0 Service Call for Repairs or ask about $69 OFF Any Electrical Service on eligible work. Be ready before the next storm with a reliable standby generator.

Call 303-536-1616 or schedule at https://fixmyhome.com/. Ask for the $0 Service Call for Repairs and $69 OFF Any Electrical Service on eligible generator work. Stay powered during the next Denver outage.

About Fix-it 24/7 Plumbing, Heating, Air & Electric

Fix-it 24/7 serves the Denver Metro with licensed, insured Colorado electricians who install, repair, and maintain standby generators. We offer 24/7 emergency service, same-day appointments, flat-rate pricing, and a 100% satisfaction guarantee. Our team holds EPA and NATE certifications, an A+ BBB rating, and thousands of 5-star reviews. We handle permits, inspections, transfer switches, and fuel systems, with financing options that make backup power more affordable.