Generator Care Rules & Regulations

What to Look For When Buying a Used Generator?


The benefits of purchasing a pre-owned or a low-hour used generator are numerous. Many individuals and large or small companies buy pre-owned generators because of their cost-effectiveness. But, you’ve to be extra careful when investing in such a unit, including understanding what you should look for when buying a used generator.

Start by understanding your power needs and requirements. Next, inspect the generator’s physical state and test run it with and without a load to check its operational integrity. Don’t order the generator yet; check the seller’s reputation and review their technical experience as it will help you understand how well they managed the unit.

That’s a brief of what to check when buying a used generator. To better explain these points, I have expounded the topic further to help anyone thinking of buying a pre-owned unit to avoid frustrations later.

What Should You Consider When Buying a Used Generator

Owning a pre-owned generator has its benefits which I will address later. The used generator can be a plus for you in many ways. However, it’s a must you make the best decision when buying one to avoid frustrations later.

Understanding what to look for during the purchase takes you closer to successfully investing in a perfect generator for your money.

Here are the key factors to consider when buying any used generator, from diesel standby generators to natural, propane, gas, or portable electric generators.

1) Power Needs & Requirements

When weighing your ideal size generator, you want to have a rough idea of what you need as per your power needs and requirement. It all starts by identifying how you want to use the generator.

Whether at home or commercial building for emergency power backup, with an RV camper or at a camping ground, understand the amount of wattage you need from the generator.

Start by writing down all the possible appliances and electrical devices you intend to run with the generator. Note them down with their wattage requirements and then add them out. You can find this information written on the back or under the appliance or device.

If the wattage isn’t indicated, you can refer to its manual. You want to check for the starting and running wattage.

If not available, check for the amperage and voltage. Multiply the two to get the running watts. Multiply the wattage values of all high-power motor-driven units by two to get their starting watts.

With the total wattage needed, you understand the minimum size generator to buy, which is 20% more of the sum you got.

2) Generator’s Overall Condition

Now that you know how big the generator needs to be, your options list has been reduced. The next thing you want to check before spending your money on the used generator is its overall condition.

  • Is the generator in good condition, okay condition, or bad condition?
  • Does the unit look like it’s brand-new out of the box or like it was hit by a truck?

a) Check for Rust and Corrosion

You want to check for signs that shout it has been exposed to elements such as:

  • Heavy faded pain, a sign showing exposure to a lot of sun rays
  • Rust and corrosion – a sign showing exposure to moisture

And as you well know, moisture and electricity aren’t friends. Suppose you see heavy rust or corrosion on the generator exterior. In that case, there’s a chance the generator head and electronics inside are in the same state, a condition that could cause problems later.

b) Look For Anything Missing or Broken

When analyzing your potential used generator, you want to check if anything is missing or broken. Anything misplaced or damaged will need replacing or fixing. You also have the option of learning to live with.

A used generator can miss some hidden parts, such as an air filter, which isn’t good. When the air filter misses, it’d mean that the engine was running, breathing dirty air, something that must be avoided at all cost.

Some other simple things, such as a disintegrated fuel gauge, can cause serious problems like allowing water into the fuel tank and enabling the gasoline fumes to escape, something you want to avoid at all cost.

Be vigilant while looking for anything missing or broken; however small, it could have a huge impact on the generator performance.

c) Look For Any Modifications

Check if the previous user(s) did any modification before listing the generator for sale. You want to make sure nothing is messed with.

Look for hacked-up wiring as it’s the most common modification done in most used generators and is known to cause problems later. Look at the generator to have a rough idea of the type of lifestyle lived and its previous care.

d) Check the Engine Oil

With oil being the lifeblood of a generator engine, it can tell you a lot about the generator and its previous maintenance routines if checked.

Most portable generators have a dipstick used for checking the oil and its level. Most of them allow you to check the oil level without screwing it in all the way.

Dip it in and check the engine oil’s color. What you need is a golden brown color, ideally at the full mark on the dipstick. But if it’s below the dipstick threads, it’s also fine.

If it’s a bit darker, it’s not that bad. However, if it’s super dark, that isn’t good, but it doesn’t mean the engine is all done. You want to check for, though at contamination, mostly metal chunks.

Hold the dipstick with the oil up to the light and look for glitter or sparkle. If you find any, the engine is all worn out, and you should avoid it.

If everything above checks out, smell the oil. You want to check if you can smell gasoline, especially if it’s overfull. In such a case, the carburetor needle or seat is leaking fuel making its way into the engine crankcase and mixing with the oil.

It’s not a deal-breaker, but you might want to acknowledge it and ask for a reduced price as you’ll have to spend your money on the repairs.

Another thing, if you don’t notice it and the generator continues to run with fuel leaking into the oil, there could be damages occurring in the engine since it won’t provide the necessary engine lubrication.

e) Check Your Air Filter

Many portable generators use foam air filters, with some using two foams, one coarse and one fine. Most standby generators, on the other hand, use cartridges.

The foam filters need oiling for them to function properly. Most people don’t know this. If it’s not oiled, the foam will dry out and disintegrate, and its remains will head directly to the engine.

At times, the engine might survive the filter remains. However, if the drying and disintegration continue and the generator owner doesn’t realize it early, it can get to the point that the generator will be breathing dirty air.

So, if the generator looks physically okay and clean, don’t forget to look at the air filter for excessive dust and dirt build-up.

If you find any dirt behind the filter and inside the carburetor, the probability is the engine is badly worn out because of it. But if it’s clean, continue with the checks.

f) Take a Look inside the Gas Tank

Most gasoline generators will have a fuel screen or filter in the fuel tank inlet for filtering the fuel out a little bit.

You want to pull it out and have a look into the fuel tank. You want to make sure there is no debris, as a significant amount can signal a problem.

If it’s a metal gasoline tank, you also need to check for rust and corrosion. Also, look for droplets floating around as that would mean water is the cause of the rust and corrosion.

These signs can mean only one thing; there might be a problem with the fuel line down the road. So, invest in a model that is nice and clean.

g) Check the Electric Start System

If the used generator has an electric start, try starting the engine using it. If the generator starts, the starter is okay; if it starts or not, look at the battery. You want to look at the manufacturing date, mostly printed at the top.

If the battery is a couple of years old, you may need a new one soon. If the generator did not start, the battery might be dead or have a wiring issue. Either way, you will need a jump starter, a battery charger, or a spare battery for testing.

h) Test the Recoil Starter

If the battery is dead, the generator should be able to start with the recoil starter. Try pulling the recoil cord and see what happens.

During the first pull, feel it and make sure there is enough engine resistance. The cable should be able to retract on itself.

If it doesn’t, there’s a problem with the recoil starter assembly, and it will need to be fixed – if not during the purchase, it will cost you later.

It might also prevent you from testing the engine and the load, something you cannot overlook when buying a used generator.

i) Test Run the Engine

So, I’m assuming you can start the generator engine by pulling the recoil cord or pushing the ignition button. Whichever you use, you want to make sure the engine runs before paying for your pre-owned generator.

Ideally, it’d be best to start the engine when cold, as a cold start can reveal issues in the generator engine that a warm start wouldn’t.

The engine should start up easily even it’s been sitting for a while, assuming it was stored properly and without fuel in it the fuel carburetor or fuel tank.

It might take few pulls to get the engine roaring, but if it’s hard to pull to a point you’re even sweating from all the pulling, it could be a sign of engine problems.

Mostly, the problem might be in the carburetor, which is a good thing, but it could also be an engine issue. I wouldn’t advise you to buy a generator that doesn’t start unless you can troubleshoot it before paying for it, and you’re getting it at a decent discount.

If it starts, check the color of the smoke. Don’t be concerned if it produces light vapor-like smoke for some minutes and it disappears. That’s is water or moisture that condensed in the exhaust.

If the generator produces black smoke, don’t worry. It’s the sign of unburnt fuel that might have been pushed out during startup.

You shouldn’t worry much either if the generator produces some white smoke at startup as it’s a sign that it’s burning some oil that might have found its way into the combustion chamber.

But, if it’s too much bluish-white, it could be a sign there is a problem with the engine where it’s burning an excessive amount of oil. Mostly it’s caused by worn-out rings and other things that require the engine to be taken apart, and that’s never cheap.

If the engine doesn’t produce any smoke, allow it to warm up and listen to the engine sound. You want to hear a nice, smooth sound without any popping, surging, or sputtering.

Surging is when the engine keeps changing the RPM and revs up and downtime without a load change.

Be keep and listen for any knocking, grinding, or any other abnormal noises. If you hear grinding or knocking noises, don’t at the generator again –walk away. The noise signals a major engine problem that could mean it’s about to die.

If you hear a rattling noise from the engine’s front, you can try applying some pressure to the recoil using your hand. The recoil or blower housing might be loose if the noise stops, which isn’t a deal-breaker. It’s quite common with some generator models, especially Briggs & Stratton.

If you hear tapping noises from the valve top cover, it could be produced by loose valves that need adjusting.

j) Check the Electrical Side

It is here that most used-generator buyers go wrong when buying a pre-owned generator. They connect a light or a small electric device to test the generator outlets, which is okay but not efficient for checking the unit’s output.

While doing the testing, make sure you check all the outlets. Most generators use common household outlets. It should be easy to do the testing.

If one outlet isn’t working, but the rest are, it can be a case of a simple replacement of the receptacle, something that won’t cost you much. However, if two or more aren’t working, there could be a significant wiring problem.

If all the outlets are okay, you can go ahead and plug in a higher load into any of them and allow the generator to run for a minute or two.

What you want is to listen to the generator as it runs. It might sound a bit different from when it is running without a load. However, it should run smoothly without sputtering, popping, surging, or backfiring. Don’t forget to identify any abnormal noises such as grinding, knocking, and other scary sounds.

While the generator is under load, watch for any smoke coming from the exhaust. You don’t want to see bluish-white smoke as it means a problem in the engine that’s allowing it to burn oil.

Most generators will disguise you with no load and bring its true colors when connecting a heavy load. That’s when you start to hear knocking and other sorts of scary noises. The engine can also begin to produce bluish-white cloudy smoke or both.

I recommend, if you’re hearing the knocking sound and getting bluish-white smoke, go ahead and pass on the generator. It’s not worth your time and money, no matter how low the price is.

k) Check the Control Panel

If the generator has a control panel, check its condition, especially if you’re buying a standby generator. You want to make sure the unit uses the original model assembled by the manufacturer. If not, ask the seller about the type of modification made and why.

Keep in mind that if the previous user changed the control panel without performing the necessary adjustment, you might have a tough time setting things up, such as operating hours.

3) Seller Reputation and Technical Expertise

If you need to invest in a reliable used generator, it’ll be best to check the seller’s reputation and technical expertise.

When doing your interview, enquire on what the generator was used for. Ask if the owner used it for continuous electric power generation or if it was used for emergency purposes.

It can help a lot. A generator used for emergency purposes will be properly maintained and will have less wear and tear than a prime model used for a continuous power generator.

If you’re buying a commercial diesel or natural gas generator, check its odometer reading to understand how many hours the unit has been running before being listed for sale.

If you need to buy a portable generator, the age and usage information won’t be available. That’s is where the seller’s reputation comes in.

If the seller bought the generator from auctions, foreclosures, and so forth, ask about the previous owner and how they used the unit.

Don’t forget to ask if the seller has any experience with the technical handling of the generator. A technically experienced seller will have an idea of inspecting, tuning, testing, fixing, and rebuilding the unit before reselling it.

If you decide to go through a dealer, make sure they are accredited to resell such machines. Also, read some buyer reviews to understand how they performed with their previous sales.

4) Manufacturer Reputation and History

Even though the generator’s model and make don’t matter much, the manufacturer’s reputation and history play a huge role when buying a used generator.

Since you’re buying a pre-owned product, you will likely require to replace some parts sooner or later. You want to make sure the generator maker is reliable when it comes to the availability of spare parts.

Also, check out how well they respond to customer support. You never know; you might need some help the instant your generator arrives home.

Why Consider Buying a Used Generator

When getting yourself ready for power emergencies caused by power outages and disasters, a backup generator or standby generator can be an excellent way to ensure you keep your home safe. You have the option of buying a new unit or a used one. With most people consider new generators, you can prefer an alternative, buying a pre-owned model.

So, what are the benefits of buying a used generator?

Lower Cost

A generator is always a huge investment move, and it gets even better if you decide to buy a new model. However, if you choose to buy a pre-owned model, you can get it at half the new or even lower price. The budget of a new generator might get you two or more of your favorite models. That’s the reason most upcoming and small businesses prefer buying used generators.


A used generator is already tested. If you get it from a certified dealer, you can be sure you’re getting something reliable and in excellent working condition. An accredited dealer will test the generator, maintain, repair, and maybe even tune it to guarantee the function and reliability of the unit. That’s to ensure the product is of a quality the customer can trust.


Finally, the greatest advantage of acquiring a secondhand generator is its versatility, other than the cheaper cost. When a manufacturer creates a new generator, the buyer is typically forced to accept it as-is. This implies that you will receive the generator in the manner in which the manufacturer designed it. When you acquire a used generator, you have more freedom to make tweaks or modifications to meet your specific demands.

Related Questions

What is the price of a secondhand generator?

The average cost of a portable generator for outdoor use is between $500 and $1000. A portable generator to use as a backup generator for your home can cost you more than twice as much. The price of a standby generator is even higher, over $3000.

About the author

Sharif Gen

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