Nashua, NH Standby Generator Installation & Maintenance Tips

Estimated Read Time: 10 minutes

If your Generac generator won’t start when the lights go out, stress spikes fast. Storms in Southern New Hampshire can knock out power for hours, and you count on your standby system to protect heat, refrigeration, and medical devices. In this guide, our licensed electricians explain the most common reasons a Generac generator won’t start and the safest fixes you can try before calling in a pro. You’ll also learn when to stop troubleshooting and schedule service, plus how regular maintenance prevents most no-start problems.

Quick Safety First

Before you troubleshoot why your Generac generator won’t start, follow these basics:

1. Read your owner’s manual. Note model number and error codes.
2. Turn the system to OFF before touching wiring, fuel, or battery.
3. Keep the area clear of snow, leaves, and debris for ventilation.
4. Never bypass safety devices or the automatic transfer switch.
5. If you smell gas or see fuel leaks, stop and call a licensed pro.

A standby generator is an automatic system. Within seconds of a grid outage, the transfer switch detects the loss and signals the generator to start. If that sequence fails, the cause is usually one of the issues below.

1) Dead or Weak Battery

The number one reason a Generac generator won’t start is a depleted battery. Batteries lose charge from age, cold weather, or long idle periods.

How to fix:

• Check battery age. Most last 3 to 5 years in our climate.
• Inspect terminals for corrosion and tighten connections.
• Use a digital multimeter. Under 12.4V usually indicates low charge.
• Charge or replace with the manufacturer-recommended spec.

Pro tip: Add battery maintenance to your seasonal checklist. Many no-start calls trace back to a simple weak battery.

2) Fuel Supply Issues (Propane, Natural Gas, or Diesel)

No fuel, closed valves, or low tank pressure can stop ignition. Generac systems run on propane, natural gas, or diesel, and each fuel has unique checkpoints.

How to fix:

• Verify tank level on propane or diesel. Refill if low.
• Open all inline shutoff valves fully and confirm meter supply for natural gas.
• Inspect flexible fuel lines for kinks or damage.
• After refills, purge air if your model requires it per the manual.

If you ever suspect a gas leak, clear the area and call a licensed technician immediately.

3) Clogged Air Filter or Restricted Intake

A choked engine cannot get the air it needs to start.

How to fix:

• Remove and inspect the air filter. Replace if dirty or soaked.
• Clear snow drifts, leaves, and nests around the intake and enclosure.
• Follow the manufacturer’s interval for filter replacement.

Tip for New Hampshire winters: After a storm, shovel out the generator pad and brush vents to prevent icing.

4) Old or Contaminated Fuel

Stale fuel causes hard starts, surging, or no start at all. Diesel and gasoline degrade faster than propane or natural gas.

How to fix:

• For diesel, use fresh fuel and a quality stabilizer per the manual.
• Drain contaminated fuel and replace filters as specified.
• Keep a maintenance log with fuel dates and filter changes.

5) Faulty Spark Plug or Ignition Components

Worn spark plugs, cracked wires, or a failed ignition coil will stop combustion.

How to fix:

• Remove spark plugs and check gap, wear, and deposits.
• Replace plugs with the correct heat range and torque.
• Inspect ignition leads for cracks or heat damage.

If your Generac generator won’t start after replacing plugs, have a pro test coil output and ignition timing.

6) Low Oil, Wrong Oil, or Poor Lubrication

Most generators include a low-oil shutdown to protect the engine. Cold weather thickens oil and can trip safeties.

How to fix:

• Verify oil level on level ground. Top off with the specified weight.
• Use winter-appropriate oil weight for reliable starts.
• Replace oil and filter on schedule to remove sludge.

Signs you waited too long include metal shavings in oil, burning smells, or constant shutdowns.

7) Coolant or Overheat Issues

Liquid-cooled units will not start or will shut down if coolant is low or circulation is blocked.

How to fix:

• Check coolant level and look for leaks at hoses and clamps.
• Inspect belts and water pump operation if accessible.
• Clear radiator fins and louvers of debris.

If the unit overheats quickly or throws a high-temp fault, call a licensed electrician to avoid engine damage.

8) Sensor, Switch, or Control Board Faults

Modern standby generators rely on sensors and the control module to manage start-up. A faulty oil pressure sensor, speed sensor, or a control board issue can block cranking.

How to fix:

• Note the exact error code on the controller.
• Power-cycle the controller if your manual allows.
• Verify all connectors are seated. Look for moisture intrusion.
• If codes persist, schedule professional diagnostics.

Our licensed electricians use manufacturer procedures to test sensors and verify the board before replacing parts.

9) Transfer Switch or Wiring Problems

A miswired or failed automatic transfer switch can prevent the start signal. Article 702 of the National Electrical Code governs optional standby systems. If installation cut corners, reliability suffers.

How to fix:

• Visually check for tripped breakers and reset if safe.
• Do not open the transfer switch enclosure unless you are qualified.
• If the generator runs in manual but not automatically, the switch or control wiring likely needs service.

Professional installation matters. Correct conductor sizing, grounding, and switch programming ensure safe, automatic operation.

10) Lack of Preventive Maintenance

Many whole-home generator repairs are caused by skipped maintenance. Batteries, belts, fuel lines, oil, and coolant are frequent failure points when upkeep lapses.

How to fix:

• Follow the maintenance schedule in your manual by hours and seasons.
• Run the weekly exercise mode and investigate any abnormal sounds.
• Log every filter, plug, belt, and fluid change.
• Enroll in a maintenance plan to catch issues before storms.

Consistent maintenance prevents most no-start situations and protects your investment.

When to DIY and When to Call a Pro

Tackle visual inspections, filter checks, battery terminals, and simple part replacements if you are comfortable and follow the manual. Stop and call a licensed electrician if you encounter:

• Fuel leaks, gas odors, or damaged fuel lines
• Persistent error codes after basic resets
• Transfer switch or control board faults
• Overheat warnings, low oil pressure faults, or repeated shutdowns

Paul The Plumber’s licensed and insured electricians service all makes and models of standby generators, including Generac. We diagnose the root cause and repair what failed, not just symptoms.

Why Your Generac Generator Won’t Start After a Storm

Heavy snow, ice, and wind create a perfect storm of no-start issues in Southern New Hampshire:

• Battery performance drops in cold snaps.
• Air intakes clog with snow and sleet.
• Propane pressure can fall in extreme cold.
• Drifting snow blocks exhaust and ventilation.

After a storm, clear the area around the enclosure, verify intake and exhaust are open, and check status lights before you need the unit.

Preventive Maintenance That Actually Prevents No-Start Calls

A smart plan focuses on the parts that fail most:

1. Battery care
2. • Voltage check every visit
   • Terminal cleaning and hold-down inspection
2. Fuel system
3. • Line and regulator checks
   • Filter replacement by hours
3. Air and ignition
4. • Air filter, spark plugs, and coil tests
4. Fluids and cooling
5. • Oil, filter, and coolant by interval
   • Belt tension and hose condition
5. Controls and ATS
6. • Error log review
   • Automatic transfer switch function test

Our Paul’s Promise Plan delivers priority scheduling, exclusive savings, and an extended 3-year parts and labor warranty on our work. Non-members still enjoy our standard 2-year parts and labor warranty.

Professional Installation Prevents Headaches Later

Improper siting, fuel sizing, or wiring can cause a Generac generator to not start reliably. Our installation process includes:

• Right-sizing your generator based on your home’s square footage and the circuits you want powered
• Preparing the outdoor pad, placing the generator, and running safe fuel lines
• Installing the automatic transfer switch and all required electrical connections
• Start-up, testing, and homeowner training

Safe, code-compliant installation means your generator starts within seconds when the power fails, without manual steps.

What Your Standby Generator Protects During Outages

A working standby generator does more than keep the lights on:

• Heats your home to prevent frozen pipes
• Keeps refrigerators and freezers cold
• Powers sump pumps to avoid water damage
• Keeps medical devices and monitors running without interruption
• Maintains Wi-Fi and essential electronics

It also boosts property value by adding reliable backup power to your home.

Troubleshooting Checklist You Can Try Today

If your Generac generator won’t start, run through this quick list:

1. Flip the control to OFF, wait 30 seconds, then back to AUTO.
2. Check battery voltage and clean terminals.
3. Verify fuel level and open all valves.
4. Inspect air filter and intake vents; clear debris and snow.
5. Review error codes in the controller menu.
6. Top off oil with the specified grade.
7. Attempt a manual start per the manual.

If the unit still will not start, schedule a licensed technician for diagnostics and repair.

Why Homeowners Choose Paul The Plumber for Generator Service

• Licensed, background-checked electricians
• 24/7 emergency availability and fast local response
• Upfront pricing with no surprises
• Repairs for gas, diesel, and propane standby systems
• 2-year parts and labor warranty on our work, 3 years for members
• 4.8 rating with 2.9K+ Google reviews

We serve Nashua, Manchester, Derry, Concord, Salem, Merrimack, Londonderry, Hudson, Portsmouth, and Dover with prompt, professional service.

Special Offers for Southern NH Homeowners

• Special Offer: Save $250 on Generac generator installation. Use code SAVE250 before 2025-12-31. Limit one per household. Not combinable. Mention at booking and present before work begins.
• Special Offer: Save $100 on generator installation. Use code SAVE100 before 2025-11-05. Limit one per household. Not combinable. Mention at booking and present before work begins.

Call (603) 541-7986 or schedule at https://www.paultheplumbernh.com/ and ask about Paul’s Promise Plan for extended warranty coverage.

What Homeowners Are Saying

"One of the most professional trade services I've used. Communication is great. You know who's coming & when. Wear shoe covers in the house and can quote the job right away."
–FirstName L., Southern NH

"John was wonderful. He found the problem right away and fixed it. He checked other outlets just to make sure I would be safe. He explained different programs the company offers also. I’m very happy."
–John’s Customer L., Generator Service

"I cannot say enough about this company!!! Their only concern is that you are up and running again with no worries."
–FirstTime C., Backup Power Repair

"Never used Paul The plumber company before but I’m glad I did. Very courteous, professional and pleasant from the answering service (Diane) to employees (Jeremy). They diagnosed the problem and fixed it in no time."
–Diane & Jeremy’s Customer L., Derry

Frequently Asked Questions

Why does my Generac generator click but not start?

A clicking sound often points to a weak battery or corroded terminals. Check voltage, clean connections, and try again. If clicking persists, have a technician test the starter, relays, and ignition.

How often should I service a standby generator in New Hampshire?

At least annually, plus additional checks before and after severe storms. Follow the hour-based intervals for oil, filters, and plugs listed in your manual.

Can low propane pressure stop my generator from starting?

Yes. Low tank level or regulator issues can prevent ignition. Verify levels, open valves, and have a pro check pressure and regulators if problems continue.

What does the automatic transfer switch do?

It senses utility power loss within seconds and transfers your home’s electrical load to the generator, then back to utility when power restores.

Will a maintenance plan really prevent most no-start issues?

Yes. Many no-start calls are caused by missed maintenance. Plans catch weak batteries, clogged filters, and fuel issues before outages.

The Bottom Line

If your Generac generator won’t start, the cause is usually simple: battery, fuel, air, ignition, oil, or maintenance. Start with the safety and troubleshooting steps above. For persistent faults or transfer switch issues, call a licensed pro.

For fast help in Greater Manchester and Nashua, call (603) 541-7986 or schedule at https://www.paultheplumbernh.com/. Mention SAVE250 to save $250 on eligible Generac installs before 2025-12-31.

Ready for Reliable Backup Power?

• Call now: (603) 541-7986
• Book online: https://www.paultheplumbernh.com/
• Active coupon: SAVE250 for $250 off Generac generator installation through 2025-12-31. Not combinable. Must be mentioned at booking and presented before work begins.

Get expert diagnostics, repairs that fix the root cause, and strong warranty protection with Paul’s Promise Plan.

Paul The Plumber is Southern New Hampshire’s trusted home services team for generator installation, repair, and maintenance. Our licensed, background-checked electricians provide upfront pricing, 24/7 emergency response, and clean, courteous service. We stand behind our work with a 2-year parts and labor warranty, or 3 years for Paul’s Promise Plan members. Rated 4.8 with 2.9K+ Google reviews, we serve Nashua, Manchester, Derry, Concord, and nearby towns.