Louviers, CO Standby Generator Service: Why Your Generac Won’t Start

Estimated Read Time: 9 minutes

Power out and your Generac generator won’t start? Take a breath. In many cases the fix is simple and safe to check. Below, our Denver electrical team walks you through the top causes and quick tests, then shows you when it’s time for a licensed, code‑compliant repair. If you need help fast, we offer same‑day and 24/7 emergency service across the Denver metro, with transparent pricing and no surprises.

Before You Start: Safety First

Working on a standby generator means working around fuel, high voltage, and moving parts. Stay safe.

• Turn the generator to OFF on the controller before hands‑on checks.
• Keep hands and tools away from the cooling fan and belts.
• Do not bypass safeties or jump wiring.
• If you smell gas, stop and call a professional immediately.
• All permanent standby systems must follow National Electrical Code Article 702 and local permitting. In Denver, permits and inspections apply for installs and major repairs.

Hard facts that matter:

1. Denver’s elevation is 5,280 feet, which affects fuel‑air mix and engine output. Generators may need altitude adjustments.
2. NEC Article 702 governs optional standby systems and transfer equipment. Compliance protects your home and utility workers.

1) Weak or Dead Battery

Symptoms: Clicking, dim controller, or no crank.

Quick checks:

1. Make sure the controller is ON and not in OFF or AUTO‑disabled.
2. Inspect battery terminals for corrosion. Clean and tighten.
3. Measure battery voltage. Most residential units use a 12V battery; replace if below spec under load.

Fixes:

• Charge or replace the battery. Many batteries last 3–5 years. Cold snaps shorten life.
• Confirm the charger is powered and fuse is intact. If you lost grid power for days, the charger may have dropped.

Call a pro if cables are damaged or the charger circuit tests bad.

2) Low Oil or Wrong Oil Viscosity

Symptoms: Unit cranks but will not start, or shuts down quickly with a low‑oil fault.

Quick checks:

1. Verify oil level on the dipstick with the unit OFF and cool.
2. Look for milky oil or fuel smell, which signals deeper issues.

Fixes:

• Top off with manufacturer‑approved oil. Many Generac air‑cooled units use 5W‑30 synthetic, but confirm your model.
• Replace oil and filter per the maintenance schedule. Many models call for annual service or at 100–200 hours.

Do not run with the low‑oil light on. That protection prevents engine damage.

3) Clogged Air Filter or Intake Obstruction

Symptoms: Flooding smell, sputtering, or no start after cranking.

Quick checks:

1. Inspect the air filter. If it is dark, oily, or packed with dust, replace it.
2. Clear leaves, snow, or construction debris from intake louvers.

Fixes:

• Install a new air filter and retest.
• In wildfire smoke or dust storms, shorten filter replacement intervals.

A starving engine cannot maintain the right air‑fuel mix. At altitude, clean airflow matters even more.

4) Fuel Supply Problems (Natural Gas or LP)

Symptoms: Cranks but will not fire, or starts then stalls.

Quick checks:

1. Confirm utility gas service is active, or LP tank is above 30 percent.
2. Make sure exterior gas valves are open and aligned with the pipe.
3. Listen for the regulator; icing in deep cold can reduce flow.

Fixes:

• For LP: have the tank filled and regulators checked. For NG: call the utility if you suspect a delivery issue.
• If appliances inside also fail, the issue may be upstream.

Gas adjustments and leak checks must be done by a licensed pro with manometer testing and permit if required.

5) Closed Valves or Frozen Regulator

Symptoms: No start during a cold snap or after a wind event.

Quick checks:

1. Inspect exterior regulators for ice buildup.
2. Verify all appliance and branch valves are fully open.

Fixes:

• Thaw naturally. Do not use open flame. Shield the regulator from wind per code and manufacturer clearance rules.
• Add a cold‑weather kit or wind baffle approved by the manufacturer.

Improper shielding can trap exhaust or violate clearances. Have a licensed electrician review.

6) Worn Spark Plug or Ignition Fault

Symptoms: Long crank, misfire, or raw fuel smell from the exhaust.

Quick checks:

1. Remove and inspect spark plug. Look for carbon, oil, or cracked porcelain.
2. Check the plug gap against the manual.

Fixes:

• Replace the plug with the exact spec and torque.
• If spark is weak, the ignition coil or wiring may be failing.

If you are not set up for safe spark testing, schedule service. Ignition faults look simple but can damage the controller if misdiagnosed.

7) Tripped Breaker or Transfer Switch Issue

Symptoms: The generator seems to start, but no power flows to the home, or it immediately shuts down.

Quick checks:

1. Inspect the generator’s output breaker. Reset if tripped.
2. Check the automatic transfer switch display for errors.
3. Verify time delay settings. A long delay can feel like a no‑start.

Fixes:

• Resetting a nuisance trip may be fine once. Repeated trips point to load, wiring, or ATS faults.
• Transfer switch and feeder connections are high‑voltage. A licensed electrician should test and torque to spec.

NEC 702 requires listed transfer equipment. Never backfeed a panel with a cord or inlet hack.

8) Controller Error Codes or Disabled Exercise Timer

Symptoms: The unit never runs its weekly exercise, then fails to start during an outage.

Quick checks:

1. Review the controller screen for fault codes.
2. Confirm the clock and exercise schedule are set correctly.

Fixes:

• Clear non‑latching faults and correct causes. Common culprits are overspeed, low battery, or loss of sensing.
• Update firmware if the manufacturer issues reliability fixes.

A generator that never exercises is a generator that surprises you. Keep the automatic test active year‑round.

9) Altitude or Cold Weather Setup Missing (Denver‑Specific)

Symptoms: Hard starts, rough running, or stalling in winter or on the first cold start of the season.

Quick checks:

1. Confirm installation altitude settings and jetting meet manufacturer specs for 5,280 feet.
2. Look for a battery warmer, oil heater, and cold‑weather kit in outdoor enclosures.

Fixes:

• Have a pro adjust fuel‑air mix and regulator pressure for altitude.
• Add manufacturer‑approved cold‑weather accessories to stabilize starting below freezing.

At a mile high, engines make less power and fuel behaves differently. Right‑sizing and setup prevent false “no‑start” calls.

10) Overdue Maintenance or Neglected Service History

Symptoms: Gradual decline, increased faults, then a no‑start during the first real outage.

Quick checks:

1. Check the service sticker. If you cannot remember your last oil, filter, and plug change, you are due.
2. Review hour meter readings against the manual.

Fixes:

• Complete an annual service: oil and filter, air filter, spark plug, valve check if required, battery test, controller firmware check, and full transfer test.
• Document results and corrective actions.

Many “mystery” failures vanish after a thorough tune‑up with torque checks and manometer readings.

When to Call a Licensed Electrician

Call in the pros when you see any of the following:

1. Gas odor, regulator frost, or suspected leak.
2. Repeated breaker trips or ATS error codes.
3. Wiring damage, rodent damage, or moisture intrusion.
4. Controller faults that return after reset.
5. You need permitting, transfer switch work, or interconnection adjustments.

We handle turnkey installations and repairs that meet NEC Article 702 and local code, including permits, ATS integration, surge protection, and panel coordination.

Preventive Maintenance That Prevents No‑Starts

A simple plan keeps your standby system reliable.

Quarterly:

1. Visual inspection for debris, animal nests, and loose fasteners.
2. Battery and charger test, clean terminals.
3. Confirm exercise timer and run logs.

Annually or 100–200 hours (model‑specific):

1. Oil and filter change with manufacturer‑approved oil.
2. New air filter and spark plug as needed.
3. Valve lash check if required by your model.
4. Manometer test and fuel pressure adjustment.
5. Full transfer test under load, plus torque checks on lugs.

Every 2–3 years:

1. Replace the starting battery.
2. Inspect and service regulators and gas piping.
3. Update controller firmware and review event logs.

Document each visit. That paper trail speeds warranty help and diagnosis.

Installation Notes for New Generators

If your current unit is aging out or undersized, consider a right‑sized replacement.

• Sizing: Account for Denver altitude derate, winter start loads, and future EV or heat pump plans.
• Location: Respect clearance, snow load, and prevailing winds that hit regulators.
• Electrical: Use listed ATS equipment, surge protection, and panel coordination.
• Permitting: Denver and nearby cities require electrical and often gas permits with final inspection.

Our team handles design, permits, trenching, ATS integration, startup, and commissioning tests.

Typical Repair Costs and Timelines in the Denver Metro

• Diagnostic and safety inspection: same‑day appointments available.
• Common repairs: batteries, plugs, filters, sensors, wiring terminations, and controller settings.
• Pricing: We provide transparent, written quotes before work. No surprise add‑ons.

Outage in progress? We offer 24/7 emergency service and carry common parts on our trucks to reduce downtime.

Service Area

We serve homeowners across the Denver metro including:

• Denver, Aurora, Thornton, Arvada, Boulder, Westminster, Centennial, Lafayette, Longmont, and Highlands Ranch.

Schedule online or call. We will confirm availability and dispatch a licensed, in‑house electrician. No subcontractors, ever.

Frequently Asked Questions

Why does my generator click but not start?

A weak battery or corroded terminals is the most common reason. Clean and tighten connections, then load‑test the battery. If voltage sags under load, replace it and verify the charger fuse and power.

How often should I service my Generac in Denver?

At least annually or every 100–200 hours, whichever comes first. High dust, smoke, or frequent outages demand more frequent oil, filter, and plug changes. Always keep the weekly exercise enabled.

Can cold weather stop my generator from starting?

Yes. At freezing temps, oil thickens and regulators can ice. A battery warmer, oil heater, and manufacturer cold‑weather kit greatly improve first‑crank success.

Is it safe to adjust gas pressure myself?

No. Gas adjustments require a manometer, leak checks, and code knowledge. Have a licensed professional set pressures and verify combustion and clearances.

Do I need a permit to replace a transfer switch?

Yes in most Front Range cities. Transfer equipment is regulated under NEC Article 702 and local amendments. We handle permits, inspections, and compliance for you.

The Bottom Line

If your Generac generator won’t start, start with safe basics: battery, oil, air, and fuel. Denver altitude and winter cold add extra variables, so setup matters. For code‑compliant diagnosis and repair in Denver and nearby cities, call the team that installs, maintains, and tests these systems every day.

Ready to Restore Reliable Backup Power?

Call Brothers Plumbing, Heating, and Electric at (720) 994-7055 or schedule at https://www.brothersplumbing.com/. Same‑day and 24/7 emergency service available. Transparent pricing. In‑house, licensed electricians. We keep your standby system ready when you need it most.

Schedule Now

• Call: (720) 994-7055
• Online: https://www.brothersplumbing.com/
• Service: Standby Generator Installation, Hookups, Maintenance, and Testing across the Denver metro.

Need fast help? We offer same‑day appointments and 24/7 emergency response.

About Brothers Plumbing, Heating, and Electric

For 40+ years, Denver homeowners have trusted Brothers for code‑compliant electrical work. Our licensed, insured, NATE‑certified techs never subcontract. We’re BBB accredited and recognized on the 2024 Colorado Titan 100 and Best of Mile High lists. Expect transparent pricing, financing options, same‑day service, and 24/7 emergency response. We integrate generators with panels, surge protection, and transfer switches, all backed by our customer‑first guarantee.