Westminster, CO Standby Generator Installation and Maintenance

Estimated Read Time: 12 minutes

If your Generac generator won’t start, you need a clear plan before the next outage. Denver storms, wildfire shutoffs, and cold snaps do not wait. This guide covers the top causes and fixes that restore reliable backup power. You will learn simple checks you can do today, when to call a pro, and how to prevent repeat failures. If your generator is beyond maintenance, call Bell Plumbing, Heating, Cooling & Electrical for a replacement generator.

Safety First

Before you troubleshoot, put safety first.

1. Turn the generator to OFF and open the main breaker to isolate power.
2. Confirm the transfer switch is in the correct position.
3. Keep hands clear of moving parts.
4. If you smell gas or see fuel leaks, stop and call a licensed electrician or your gas utility.

Home standby generators tie into your home’s electrical system through a transfer switch. Installing or operating without a transfer switch violates code and can cause backfeeding. Never bypass safety gear. If in doubt, call a pro.

1. Battery Is Weak or Dead

Symptom: You hear clicking, slow cranking, or no crank at all.

Why it happens:

• Batteries age out every 3 to 5 years.
• Winter cold saps voltage on the Front Range.
• Loose or corroded terminals increase resistance.

How to fix:

1. Check battery voltage with a multimeter. Look for about 12.6 volts on a 12V battery.
2. Tighten terminals and clean corrosion with a baking soda solution.
3. Charge the battery or replace it if it fails a load test.
4. Confirm the battery charger is powered and connected.

Pro tip: Install a cold weather battery warmer if your unit sits outdoors in Denver’s subfreezing nights.

2. Unit Is Set to OFF or Not in AUTO

Symptom: The generator never starts during outages or weekly tests.

Why it happens:

• Control is left in OFF after maintenance.
• Auto-run schedule is disabled.

How to fix:

1. Verify the control panel shows AUTO or READY.
2. Check the clock, date, and exercise schedule.
3. Run a manual test cycle to confirm operation.

Exercise runs keep batteries charged and fuel systems healthy. Set it to run at least once a week for 12 to 20 minutes.

3. Fuel Supply Is Closed or Empty

Symptom: Cranks but does not fire up, or starts then stalls.

Standby units typically use natural gas or liquid propane. Some models run on diesel. If fuel is not available, the engine cannot run.

How to fix for natural gas:

1. Confirm the gas shutoff at the meter and appliance is open.
2. Check for utility outages or low pressure in your neighborhood.
3. Inspect flexible gas line for kinks or damage.

How to fix for propane:

1. Check tank level. Many tanks need at least 20 to 30 percent to hold pressure in winter.
2. Open the service valve fully.
3. Ask your propane provider to verify regulator settings.

Never use starter fluid. If you smell gas, stop and call a professional.

4. Clogged Air Filter or Blocked Intake

Symptom: Engine cranks, coughs, or runs rough and stalls.

Why it happens:

• Dust, pine needles, and cottonwood fluff block airflow.
• Snow and ice pack the intake after a storm.

How to fix:

1. Inspect and replace the air filter if it looks dirty or wet.
2. Clear leaves and debris from all louvers and vents.
3. Maintain a clear area around the enclosure, at least 3 feet on all sides.

Clean air is essential for proper combustion. A simple filter swap often restores smooth starts.

5. Old or Contaminated Fuel (Propane or Diesel)

Symptom: Hard starts, surging, or no start after months of sitting.

Why it happens:

• Propane tanks with heavy moisture can cause regulator freeze.
• Diesel can grow microbes and absorb water.

How to fix:

1. For propane, keep tanks above 20 percent and consider a regulator cover.
2. For diesel, drain water separators. Use a biocide if contamination is present.
3. Schedule a fuel system inspection if symptoms persist.

In cold snaps, moisture and pressure swings hit fuel systems hardest along the Front Range.

6. Fault Codes on the Control Panel

Symptom: The panel shows an error and locks out starting.

Common codes include low oil pressure, overspeed, overcrank, or under-voltage.

How to fix:

1. Note the exact code before clearing it.
2. Check oil level on a level surface. Top off with the manufacturer’s recommended oil.
3. Verify the main breaker and control fuses are intact.
4. Try a single restart after corrections.

If the code returns, stop. Repeated cranking can flood the engine or drain the battery. A licensed electrician should diagnose sensor or control issues.

7. Transfer Switch Problems

Symptom: The generator runs, but the house does not get power, or the unit will not start on outage.

Why it happens:

• Stuck or failed switch contacts.
• Incorrect sensing of utility power.
• Wiring faults or outdated panels.

How to fix:

1. Confirm the utility power status light on the switch.
2. Verify the switch is not in the bypass or manual position.
3. Do not open the switch enclosure unless you are qualified. High voltage is present.

Home backup generators require a transfer switch for safe operation. Installing a generator without the transfer switch is a code violation and can cause backfeeding.

8. Spark Plug or Ignition Failure

Symptom: Cranks with no ignition or uneven firing.

Why it happens:

• Worn electrodes or incorrect gap.
• Damaged ignition coils or leads.

How to fix:

1. Remove and inspect the spark plug. Replace if fouled, cracked, or worn.
2. Set the gap to manufacturer specs.
3. Check wiring to the ignition module for secure connections.

Regular tune-ups prevent most ignition failures and keep emissions within limits.

9. Low Oil, Wrong Oil, or Clogged Filters

Symptom: Unit shuts down with low oil pressure or will not start after sitting.

Why it happens:

• Oil breaks down with heat and time.
• Cold viscosity is too high for winter starts.
• Oil or fuel filters clog.

How to fix:

1. Use the recommended oil weight for Denver winters. Many models call for synthetic 5W-30 in cold climates.
2. Replace oil and filters at least annually or at hour intervals.
3. Check for leaks at the pan, filter, and drain plug.

Fresh oil and correct viscosity protect bearings and help the engine spin freely in cold weather.

10. Wrong Size Generator for Your Home

Symptom: It starts, then trips, or cannot carry essential loads.

Why it happens:

• Undersized units struggle with large HVAC loads.
• Additions or remodels changed demand.

Sizing facts:

• Homes with a three-ton AC often pair well with an 11 kW unit.
• A five-ton AC may require 20 kW or more.

How to fix:

1. Get a load calculation that includes HVAC, well pumps, and EV chargers.
2. Consider soft starters on large air conditioners to reduce inrush current.
3. If needed, upgrade the generator or manage loads with smart modules.

The correct size protects appliances, reduces nuisance trips, and keeps lights on when Denver’s grid is strained.

Preventive Maintenance That Actually Works

A little care prevents most no-start calls.

• Run the weekly exercise cycle and listen for odd sounds.
• Replace oil, filters, and spark plugs on schedule.
• Keep batteries warm and on a healthy charger.
• Clear snow and debris from vents after storms.
• Inspect gas line fittings and flexible connectors.

When to Call a Pro Immediately

Call a licensed, bonded, and insured electrician if you notice any of the following:

1. Fuel leaks, gas odors, or regulator icing.
2. Repeating fault codes or tripped breakers.
3. Wiring damage, scorch marks, or corrosion inside the enclosure.
4. Transfer switch will not change state or makes buzzing sounds.

We handle permits, inspections, and code compliance. That includes safe gas piping, correct wire sizing, and proper clearances.

Installation, Upgrades, and Smart Backup Options

If your unit is aging or undersized, an upgrade can save money and stress.

• Full-service installation: in-home assessment, custom design, flat-rate quote, permits, professional installation, and post-install testing.
• Fuel choices: natural gas, liquid propane, or diesel based on your site.
• Load management: pair large AC systems with soft starters or smart modules.
• Transfer switches: matched to your panel for safe, automatic changeover.

Bell is also a certified Tesla Powershare installer serving the Greater Denver Metro. If you own a Tesla vehicle or Powerwall, we can design an emission-free backup solution that integrates with your home. Many homeowners choose a hybrid plan that combines a standby generator with storage for quiet, short outages and storm-ready resilience.

Our team has served Denver neighborhoods like Highlands Ranch, Castle Rock, and Arvada for decades. We understand local code and permit workflows with area inspectors.

Frequently Asked Questions

Why does my Generac click but not start?

A weak battery or corroded terminals is the most common cause. Check voltage, clean connections, and confirm the charger has power. Replace the battery if it fails a load test.

Can cold Denver weather prevent my generator from starting?

Yes. Cold reduces battery output and can affect fuel pressure. Use the correct oil weight, add a battery warmer, and keep propane tanks above 20 to 30 percent.

Do I need a transfer switch by code?

Yes. A transfer switch is required for safe operation. Without it, backfeeding can occur and violates electrical code and utility rules.

Conclusion

For expert help on replacing a Generac generator that won’t start in Denver, schedule a same-day visit. We will provide an upfront replacement price.

Ready to Restore Reliable Backup Power?

Call Bell Plumbing, Heating, Cooling & Electrical at (720) 740-0350 or schedule online at https://bellplumbing.com/. Ask about smart upgrades, including Tesla Powershare integration. Get a flat-rate quote before work begins and our 100% satisfaction guarantee. Keep the lights on when Denver’s weather does not cooperate.

About Bell Plumbing, Heating, Cooling & Electrical

Since 1926, Bell has served the Greater Denver Metro with licensed, bonded, and insured electricians. Homeowners choose us for transparent, flat-rate pricing, permits handled, and a 100% satisfaction guarantee. Our team installs standby generators, transfer switches, and Tesla Powershare systems. Expect shoe covers, tidy workspaces, and clear options before we begin. Awards include regional service honors and BBB recognition. We bring a century of local expertise to every job.