How to Repair a Generator: Fix No-Start, No-Power & Pull Cord Problems Yourself

Most generator problems come down to four things: stale fuel, a dirty spark plug or air filter, a failed voltage regulator, or a broken pull cord. This guide shows you how to repair a generator yourself, step by step. It covers the five-minute inspection, getting a generator that won’t start running again, fixing a generator that runs but gives no electricity, and replacing a pull cord. You’ll also see exactly when to stop and call a technician.

The steps are written for portable gasoline generators (Champion, Predator, Westinghouse, DuroMax, Firman, Honda and similar). They’re based on common workshop repairs and manufacturer service procedures. If you own a home standby generator, skip to when to call a pro. Those units run on natural gas or propane and connect to your electrical panel, so they need a licensed technician.

Before You Start: Generator Repair Safety

Generators combine gasoline, hot metal and high voltage, so take two minutes on safety before touching anything.

• Run it outdoors only. Test-run the generator at least 20 feet from doors, windows and vents. Never run it in a garage, even with the door open. Carbon monoxide has no smell and can kill in minutes.
• Disconnect everything. Unplug all cords and switch the main breaker on the generator off before working on the electrical end.
• Pull the spark plug wire before working near the engine, flywheel or pull cord, so it can’t fire by accident.
• Let it cool. The muffler and cylinder stay hot for 20–30 minutes after running.
• Drain fuel safely into an approved gas can, away from sparks and pilot lights.
• Never backfeed your house by plugging a generator into a wall outlet. Use a transfer switch or an interlock kit installed by an electrician.

Tools You’ll Need

Tool or part	What it’s for	Typical cost
Socket set (8, 10 and 12 mm) with a swivel or extension	Covers, drain plug, AVR and recoil bolts	$20–$40
Spark plug socket	Removing and fitting the plug	$5–$10
Digital multimeter	Testing outlet voltage and parts	$20–$40
Funnel, drain pan and approved gas can	Oil changes and draining stale fuel	$15–$25
Spare fuel line (short length)	Draining the tank from the fuel tap	$5
Carburetor cleaner and fuel stabilizer	Gummed carburetors and storage	$8–$15
Owner’s manual	Oil type, oil capacity and plug gap	Free (on the maker’s website)

Diagnose the Problem: Symptom, Cause and Fix

Match what your generator is doing to the most likely cause before you buy any parts.

Symptom	Most likely cause	DIY fix?
Won’t start, or starts then dies	Stale fuel, clogged carburetor, low oil, fouled spark plug	Yes, usually
Runs only with the choke on	Partly blocked carburetor jet	Yes (carb clean)
Engine runs but no electricity	Tripped breaker, failed AVR, worn brushes, lost residual magnetism	Often
Low or unstable voltage, lights flicker	AVR, dirty carburetor (engine hunting), overload	Often
Pull cord won’t retract, snaps back or breaks	Broken recoil spring or stuck pawls	Yes
Black smoke, sooty plug	Running rich: choke stuck or dirty air filter	Yes
White or blue smoke	Overfilled oil, or worn rings and valves	Check oil first, then call a pro
Fuel leaking from the carburetor	Stuck float or bad needle valve	Moderate
No compression, seized engine	Internal engine damage	No, get a repair quote

Step 1: Do a 5-Minute Inspection

Most “broken” generators simply missed basic maintenance, and anyone learning how to repair generators should start here. Run through these four checks first. They solve more problems than any part you can order.

1. Check the oil level and condition

Pull the dipstick and check both the level and the color. Many portable generators have a low-oil sensor that stops the engine from starting, or shuts it off after a few seconds, when the level drops. Dark, gritty or milky oil should be changed (see how to change generator oil).

2. Clean the air filter

The air filter sits in a small housing on the side of the engine. Look for heavy dust and dirt. Most small generators use a foam element: wash it in warm soapy water, let it dry completely, then add a few drops of clean oil and squeeze out the excess before refitting. Replace a paper element if it’s dirty or torn.

3. Inspect the spark plug

The plug sits at the top of the cylinder head under a rubber cap (the HT lead). Wiggle the cap off, and use a spark plug socket and a swivel if the frame is in the way.

• Light tan or gray tip: healthy.
• Black, sooty tip: the engine is running rich (too much fuel). Check the choke and air filter.
• Wet with fuel: flooded. Let it dry, or crank with the plug removed.
• White, blistered tip: running lean or hot. Often a sign of a partly blocked carburetor or an air leak.

The part number is printed on the plug, so a parts store can match it. Spark plugs cost about $5–$10. Set the gap to the spec in your manual.

4. Check how old the fuel is

This is the most important check. Gasoline, especially ethanol blends, starts to go stale in as little as 30 days without stabilizer, and gas that has sat for several months often won’t burn properly. It also leaves varnish in the carburetor. If the fuel has been in the tank for more than a few months, drain it:

1. Turn the fuel valve (below the tank) to OFF.
2. Pull the fuel line off the carburetor side of the valve.
3. Attach a spare length of fuel line, point it into an approved gas can and turn the valve ON to drain.
4. Drain the carburetor bowl too, using the small drain screw at the bottom if your model has one.
5. Refill with fresh gasoline mixed with fuel stabilizer.

How to Fix a Generator That Won’t Start

Let’s be honest: most people skip the inspection, pull the cord fifty times, and then search for “how to repair a generator”. If yours won’t start, work through these in order:

1. Check the basics: fuel valve ON, engine switch ON, choke CLOSED for a cold start, and the generator on level ground (the low-oil sensor is sensitive to tilt).
2. Top up the oil to the full mark.
3. Test for spark: refit the plug into its cap, hold the metal body against the engine with insulated pliers and pull the cord. You should see a blue spark. No spark points to the plug, the ignition coil or the kill switch wiring.
4. Prime the carburetor: on many small engines you can open the air filter cover and gently work the choke or throttle plate (the butterfly valve) a few times. This lets a little fuel drip into the intake and makes starting easier. Don’t pour gasoline into the intake.
5. Clean the carburetor: if it still won’t start, or only runs on choke, varnish is probably blocking the main jet. Remove the float bowl, spray the jet and passages with carburetor cleaner and blow them clear. A replacement carburetor for most portable generators costs $20–$60.
6. Electric start models: charge or replace the battery (12V batteries usually last 2–3 years) and check the starter connections.

How to Repair a Generator With No Electricity

This is the second most common problem: the engine runs smoothly, but nothing comes out of the outlets. In one typical workshop case, a generator was running perfectly but producing only about 6 volts AC instead of the normal output. Here’s how to track the fault down.

1. Check the breakers and outlets

Press every circuit breaker and GFCI reset button on the panel. An overload trips them easily. Then measure each outlet with a multimeter set to AC volts. On a US generator, expect about 120V on standard outlets and about 240V on the twist-lock outlet.

2. Inspect the automatic voltage regulator (AVR)

The AVR is a small black box behind a cover on the generator (alternator) end of the unit, usually held by two 8 mm or 10 mm bolts. It’s the most common failure when an engine runs fine but there’s little or no voltage.

1. Engine off, spark plug wire disconnected, cords unplugged.
2. Remove the end cover and unbolt the AVR.
3. Look for a bulging or blown capacitor, burn marks or a melted connector. That’s your fault.
4. Note which wires go where, or take a photo. The AVR usually plugs into a block connector, and two wires (often yellow and blue) go to the brush holder.
5. Fit the replacement AVR, refit the cover and test the outlets with your multimeter.

AVRs usually fail from age or from power surges when a heavy load (an air conditioner, well pump or power tool) kicks in. Replacement units are cheap, typically $15–$60 depending on the model. To protect the new one, start the generator with nothing plugged in, then add loads one at a time with the biggest first.

3. Check the brushes

Many generators use two carbon brushes that ride on slip rings. Worn-down, cracked or sticking brushes cause weak or no output. A brush set is usually under $20.

4. Restore residual magnetism (“flashing the field”)

A generator that sat unused for a long time, or was shut down under load, can lose the small magnetic charge it needs to start producing power. Many manufacturers describe a “field flashing” procedure in the manual. Follow your model’s instructions exactly, or have a technician do it.

5. When it’s the stator or rotor

If the AVR, brushes and breakers all check out, the fault may be in the stator or rotor windings. Testing them means comparing resistance readings against factory specs. The repair costs about $250–$1,500 and is usually done in a shop.

How to Repair a Generator Pull Cord

A pull cord that won’t retract, snaps back violently or breaks is another everyday failure. When the cord yanks back hard as the engine tries to fire, the ratchet (pawls) is usually stuck or the recoil spring is broken.

1. Disconnect the spark plug wire.
2. Remove the bolts holding the recoil starter cover (often 10 mm) and lift the assembly off.
3. Clean out dust and debris. Generators from building sites are often packed with it. Lightly lubricate the pawls and pivot.
4. If the cord now retracts smoothly, refit the assembly. A clean-up often helps, but sometimes only for a while.
5. If the spring is weak or broken, replace the complete recoil starter assembly. It’s easier and safer than rewinding a spring, and usually costs $15–$30.

How to Change Generator Oil

1. Run the engine for a few minutes so the oil flows better, then switch it off.
2. Remove the drain plug (often 10 mm or 12 mm; many units have one on each side) and drain into a pan. Remove the dipstick too, so the oil flows faster.
3. Refit the drain plug.
4. Refill through the dipstick hole with a funnel. Check your manual for the exact capacity. Small engines hold very little oil, often only about 0.6 quart (600 ml), so they’re easy to overfill.
5. Check the level on the dipstick and top up a little at a time.

Change the oil after the first 20–25 hours on a new generator, then every 50–100 hours or at least once a year. Take used oil to an auto parts store or recycling center.

Generator Maintenance Schedule

Task	How often
Check oil level	Before every use
Run under light load for 15–20 minutes	Monthly
Clean the air filter	Every 25–50 hours, more often in dusty conditions
Change the oil	Every 50–100 hours, or yearly
Replace the spark plug	Every 100 hours, or yearly
Stabilize or drain fuel	Before storing longer than 30 days
Professional service and load test	Every 1–2 years, or before storm season

How Much Does Generator Repair Cost: DIY vs. a Pro?

Repair	DIY parts	Professional repair
Spark plug and air filter tune-up	$10–$25	$50–$150
Carburetor clean or replacement	$8–$60	$60–$500
AVR (voltage regulator)	$15–$60	About $80 for the part, plus labor
Recoil pull cord assembly	$15–$30	$60–$150
Stator and rotor	Not a DIY job	$250–$1,500
Engine repair	Varies	$50–$2,000
Diagnostic or service call	—	$100–$200, often credited to the repair

Professional prices are national ranges from the HomeAdvisor generator repair cost guide; DIY part prices are typical retail ranges. Get a written estimate for your model.

Repair or replace? A portable generator is usually worth repairing if the engine has good compression and the fix costs less than about half the price of a comparable new unit. Replace it if parts are discontinued, the engine is seized, or it no longer covers the loads you need.

When to Call a Generator Repair Technician

DIY makes sense for fuel, filters, plugs, oil, AVRs and pull cords. Stop and call a professional when you see any of these:

• A home standby generator (Generac, Kohler, Briggs & Stratton, Cummins), its controller or the automatic transfer switch.
• Any natural gas or propane smell or line work. That needs a licensed gas fitter or plumber.
• Wiring the generator into your house panel. That needs a licensed electrician and, in many cities, a permit.
• No compression, knocking, a seized engine, or blue smoke that won’t clear.
• A stator or rotor fault, or warranty work on a newer unit.
• A commercial or diesel generator for a business, clinic or apartment building.

Where to Get Emergency Generator Repair (and Who Can Repair a Generator)

If you’re asking “where to repair my generator?” or “who can repair a generator near me?”, these are your main options:

Option	Best for	What to expect
Generator repair company	Standby, commercial and emergency repairs	On-site service, maintenance plans, often 24/7 in storm season
Mobile generator technician	Heavy portables when the power is already out	Comes to your home or job site
Small-engine repair shop	Portable generators, planned repairs	Drop-off service, usually the lowest cost
Authorized brand dealer	Warranty repairs (Honda, Generac, Champion)	Genuine parts; check the maker’s dealer locator
Licensed electrician	Transfer switches, interlock kits, inlet boxes	Permit and code-compliant wiring

Find generator repair near you

Repairior lists generator repair, maintenance and installation companies with real customer reviews. Open the directory, enter your city or ZIP code, and you’ll see the companies that serve your area, with ratings, services and contact details. You can also send one free quote request and let local technicians come to you. Need help today? Use the emergency filter to see companies offering urgent service.

Find generator repair near you Get free generator repair quotes Find emergency generator repair

Top-rated generator repair companies on Repairior

A few of the generator repair companies listed on Repairior. To see the ones closest to you, search by your location or browse all generator repair companies.

What to tell the technician for an accurate quote

• Brand, model and size (watts or kW) from the data plate.
• The exact symptom: won’t start, no power, surging, smoke or leaks.
• What you’ve already checked (fuel, oil, plug, breakers).
• Fuel type: gasoline, propane, natural gas or diesel.
• How urgent it is: power out now, storm coming, or planned service.

Generator Repair FAQs

How do I fix a generator that runs but has no power?

Reset the breakers first, then test the outlets with a multimeter. If voltage is low or zero, inspect the automatic voltage regulator (AVR) for a blown capacitor, check the brushes, and try your manual’s field flashing procedure. If none of those fixes it, have a technician test the stator and rotor.

Why won’t my generator start after sitting?

Stale fuel is the usual cause. Gasoline breaks down within weeks without stabilizer and leaves varnish in the carburetor. Drain the old fuel, add fresh gas, check the oil and spark plug, and clean the carburetor if it still won’t start or only runs on choke.

Can you repair a generator yourself?

Yes, for most portable generator problems: fuel, air filter, spark plug, oil, carburetor cleaning, AVR replacement and pull cords. Leave standby generators, gas lines, transfer switches and internal engine or stator repairs to licensed professionals.

How much does it cost to repair a generator?

Simple DIY fixes cost $10–$60 in parts. Professional repairs typically run $150–$600, plus a $100–$200 service call, and major engine or stator work can reach $1,500–$2,000.

Where can I get my generator fixed near me?

Search the Repairior directory for generator repair companies, or request free quotes to hear from several local technicians at once. Small-engine shops and authorized brand dealers also repair portable generators.

Who can repair a generator in an emergency?

Generator repair companies and mobile generator technicians offer emergency service, often 24/7 during storm season. On Repairior, use the emergency filter to find them.

How do I know if my generator’s voltage regulator is bad?

Signs include very low or zero voltage while the engine runs normally, voltage that swings up and down, or lights that flicker. A visual check often shows a swollen capacitor or burn marks on the AVR.

How often should a generator be serviced?

Check the oil before every use, run it monthly, and change oil, filter and plug about once a year or every 50–100 hours. A professional service with a load test every one to two years catches problems before an outage.

Conclusion

Knowing how to repair a generator mostly means knowing where to look first. To recap:

• Start with the 5-minute inspection: oil, air filter, spark plug and fuel age.
• A generator that won’t start almost always needs fresh fuel and a clean carburetor.
• A generator that runs with no power usually has a failed AVR, worn brushes or a tripped breaker.
• Pull cord problems are fixed by cleaning, or by replacing the recoil assembly.
• Call a pro for standby units, gas lines, transfer switches and internal engine or stator faults, and get free quotes to compare prices.

About This Guide

Editorial policy

This guide was written by David C and fact-checked by the Repairior Editorial Team using manufacturer service procedures and common workshop repairs. We update it when products or safety guidance change. Businesses cannot pay to be included in our guides.

Content transparency

Repair steps are general guidance for portable gasoline generators. Always follow your owner’s manual and its safety warnings. Prices are estimates, not quotes. Repairior earns revenue from optional business plans, which do not affect the companies shown in this article.

About the author

David C is part of the Repairior Editorial Team, which researches repair services and common equipment faults across the US. We combine technician advice, manufacturer documentation and customer feedback to help homeowners and businesses decide when to fix things themselves and when to hire a reliable pro.

Helpful official resources: CPSC portable generator safety, CDC carbon monoxide poisoning prevention, OSHA portable generator safety and EPA used oil recycling.