Generator Maintenance To Be Sure It Works When You Need It Most


Do you have a generator? You probably do. It’s one of the most common preparedness items. They do a great job for short-term power outage emergencies. Many people own one.

However many of these same people ignore (or don’t know about) generator maintenance. It’s crucial. Be assured that during the next power outage, your generator will be ready to run. Imagine firing up your generator in the middle of a wintery snow storm (or the aftermath of any grid-down situation) only to discover it doesn’t start?!

Here are some important generator maintenance considerations:

Run The Fuel Dry When Done

Gasoline is formulated to be optimum for only 1 – 3 months. After that, gasoline molecules react with each other and will eventually become sticky varnish that can clog fuel filters, fuel lines, and carburetor jets.

So consider this… If you have a tank of gasoline that has not been used in a reasonable length of time (e.g. months), the gasoline may likely cause problems with the fuel delivery system. It might prevent proper operation of the engine. This is particularly true with portable generators because they often sit unused for quite some time.

Shut off the fuel valve

One solution to this problem is this: Remember to shut off the fuel valve while the generator is still running, and let the generator run itself out from fuel starvation (which will probably take a minute). Since the fuel shutoff valve isolates the gas tank from the carburetor, once the generator uses up that remaining fuel you will know that the delivery system and carburetor is cleared of all fuel — nothing left to gum up the works over time.

Fuel Additive (Stabilizer)

A solution to increase fuel shelf life: Gasoline fuel stabilizer / additive. It will extend fuel life up to a year or more. This will also inhibit the fuel from gumming up inside the carburetor when it’s sitting idle in your generator. There are two commonly used fuel stabilizers, both of which work well.

STA-BIL Fuel Stabilizer
(view on amzn)

Better, but more expensive:
PRI-G Fuel Stabilizer
(view on amzn)

Another popular fuel additive is Sea Foam.
> Here’s an article about what people are using it for

Ethanol-free Fuel

When able to do so, use ethanol-free gasoline for your generator! Highly recommended. This will greatly help reduce chances of gumming up the works. This gas will store better / longer. I use it exclusively for ALL of my small engines around the homestead.

Periodic Running

A major problem with long term storage of a generator (besides the fuel deterioration) is corrosion of the engine and generator bearings when the lubricating oil becomes stagnant around the bearings.

Every 90 Days

As a preventative measure, run the generator every 90 days for the lubricating oil to get mixed up in there – and the bearing surfaces coated with oil.

Run it until it’s Hot

It is also a good idea to operate the generator engine at least until is reaches normal operating temperature. Water is created during the combustion process. When a generator is started and then shut down while the engine is still cold, the moisture remains in the cylinder and valve areas. This promotes corrosion. If the engine is warm when it is shut down, most of the moisture evaporates before the engine cools down.

Does your generator have a battery?

Additionally, if you have a generator with a battery (electric start), by running it once in awhile you will keep the battery charged up!

Put a load on it

Also, put a load on the generator! Make sure it’s actually working (making electricity!).

Note: Disconnect the load prior to starting, and prior to stopping. Load only while running.

Check The Oil Level

Some generators are designed to automatically shut off if the oil level runs low. However there are MANY generators that will not shut off when the oil runs low.

If the oil runs out, you will destroy your generator engine.

This is easily prevented by habitually checking the oil level! Simple – but many people don’t think of it…

[ Read: Best Fuel Additive For Generators ]
[ Read: Best Extension Cord For Your Generator ]
[ Read: Generator Safety ]

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  1. Wow Ken. We must be on the same wave length. DH got ours out this morning to service and make sure it ok to go. We also topped off all the propane tanks to RV, grills and deck fire place. As well as my sister’s grill just down the street. I’m about sure we’re as ready as possible for any civil unrest in small town U.S.A.

  2. I try to run mine every month, usually doesn’t happen but I get to it so several times a year.
    That picture above is a champion something.
    I like changing the oil, easy and quick like minutes and I use a thinner oil during winter 5w30or 0w30 whatever I happen to have on hand.
    for stabilizer I prefer pri-g but can’t get that in my part if WI so I fell back on stabil.
    Typically 30 minute runtime on warm days, 45 min on cold days is my preference.

    years ago I had 10w30 in the 3,500w generator.. I was lifting the generator off the ground trying to start it on a 10F night did not work.

  3. Serviced our primary generator recently. Our back-up hasn’t been pressed into service for quite awhile, but test ran regularly.

    On batteries….our primary generator came with a proprietary gel cell battery located in a box that only that particular odd shaped battery would fit. It lasted about three years and went belly up. Of course, that specific battery cost about $150 dollars. I built a battery box, bought longer cables, and installed one of Wally World’s basic riding lawn mower batteries. Battery, cables, everything, cost a little over $50. Been over two years ago…still running strong…and the batteries on either of my riding mowers will interchange in a pinch. Something to consider when faced with similar.

  4. Why not just use inverters, instead of generators?

    While a generator isn’t very easy to transport, an inverter is…seeing as there are so many CARS and TRUCK engines out there…isn’t it better to use an 2500 watt inverter, rather than a generator?

    An inverter is the size of a cake box, and can be easily transported anywhere. If your car works, so will your inverter. There are lots of cars, not as many generators…and any car or truck will become your generator with an inverter. Cars have huge gas tanks. Generators do not. Cars move where you want them to go….easily. Generators do not.

    Have car. Have power.

    1. Not necessarily,
      if you draw 2500w off an inverter on your vehicle for more than a few minutes intermittently, you will kill the battery and burn up the alternator, not made as a continuous duty generator unless you have a high output continuous rated alternator like what an ambulance or wrecker would have.

      1. That being said, something is better than nothing. If you can’t afford a genny, or have no place to store it, definitely have an inverter on hand. As you say though, know that it’s a limited thing! You don’t want to lose power AND transportation! Back in the day, a car with a full battery and a bad generator or alternator could run all day long. These days, EVERYTHING is riding on the car’s power. You’d be lucky to get ten miles if the alternator dies!

      1. I actually have several inverters.
        2 50
        4 400 watt
        a 600 watt
        the two 2,000 watt
        and 5 working generators.
        1- 1,600 watt
        2- 3,500 watt
        1- 5,000 watt
        1,000 watt.

    2. I have 2 2000 watt inverters. unlikely to use them.
      My single cylinder 3,500 watt generator uses far less gas than my 4 cylinder vehicle.

      2,000 watt inverter verses 3,500 watt generator.

      3,500 watt genny has wheels, less portable but I can get it most places the vehicle cannot.
      Both make considerable noise with the car being near 20bB quieter.

  5. 10 years ago purchased 4500 watt generator. Put oil in it. Never fueled or ran it. Made the purchase suddenly stopped having outages.

    Recently purchased 900 watt fuel-oil mix harbor freight generator price was too good with sale and harbor freight coupon.

    Have outdoor location set up for the 4500 where it can be chained and locked above elevation. Even the grounding is ready. Have dedicated high gauge extension cords.

    So ill be doing the oil change soon enough. Its indoor boxed, covered, and climate controlled.

  6. 8500 with a 10000 watt surge portable. Like others run it once a month, shut off the fuel to run dry. After winter I siphon out the fuel, run it dry and fill with new treated, burn the old stuff in the lawn tractor or truck. Diligent on oil changes, filters and battery trickle charge. I have a Gen Tent (company out of New Hampshire, not promoting or affiliated) that protects the running generator during snow, sleet and rain to run outdoors once pulled from the storage shed. Also check the cable wear from the generator to the house connection, if so wired. Have an emergency storage box in the basement with the cable, cloths, headlamp, gloves and such to suit up quickly and get powered up. Also extra fuel and engine oil. Hindsight is 20-20, should have coughed up for a automatic propane generator. Not fun outside in the winter hooking up.

  7. Dang it sometimes I wish there was an easy way to communicate off line! Since yesterday I have filled two 50 cubic yard roll off dumpsters with brand new, old-stock generator spare parts; to make room for the ’21 line. Typically the neighborhood ‘dreamers’ empty it out before the garbage truck can.

  8. TS Zeta blew through the North GA mountains early this morning and we lost power at 0500 and it just came back on a few minutes ago. We have a Generac 11kw automatic whole house propane generator however I only run it for 30 minutes every 4-5 hours when the power is out to keep the freezer and refrigerators cold and we plan our showers, cooking and dish washing around these times.

    I also have a 9.5kw portable propane generator as a back up with several 40Lbs propane tanks. Both get run every month and since we lose power quite a bit back up here they stay in tip top shape. We keep extra air filters, spark plugs, oil, oil filter on hand because you never know when the power is NOT coming back on for a few years.

    1. RC, I just purchased a dual fuel generator (gasoline and propane). Does it matter what type of propane tank I use? When doing research on the generator, someone said not to use Blue Rhino tanks but they didn’t give a reason. Your thoughts. Thanks.

      1. @ Senior Chief
        Don’t know why someone said not to use blue rhino tanks.
        I have a dual fuel and have ran it on every type of tank from 20# to 250 gallon. No problems at all. The best thing I have noted, is it seems the propane burns cleaner. I did a 30 hour run on mine and the oil was very very clean. Spark plugs also. I like having the dual fuel option.

      2. MS Senior Chief,

        I believe that Blue Rhino had a reputation for being under-filled…don’t know if it was deserved or not. The tanks themselves are fine…accumulated a few over the years…as my personal tanks approached age requiring them to be recertified, I would swap them in for filled tanks at Wally’s.

        1. I have two Blue Rhino and five of my own. My own tanks are filled at the l9cal hardware store. When running my propane smoker with the Blue Rhino tanks I have a hard time holding the cooking temperature, my hardware store tanks hold rock solid and can hit higher temperature if wanted. I suspect the Blue Rhinos are pressurized than the local fills, less velocityon the gas expansion delivery, just speculation.

      3. MSCS
        As Dennis stated below, the only negative I have heard about Blue Rhino is under filling. I take my tanks to Tractor Supply or Ace Hardware to have them filled.

        1. -Supposedly the underfilling is in the name of “safety”, but it means we pay more for what gas we do get.

          -Papa S.

  9. Ahahah….we just had our oldest one fully serviced! Great minds think alike. We have a few 7500+ watt . You know, the old one is none theory. Anyway, each of ours is able to stand alone run the whole house, freezers etc and the well. But always a great idea to have backup (s).

    1. Pioneer Woman
      my thoughts exactly. Anything mechanical can fail and usually happens when it’s needed most.

  10. Champion generator I am sure will need the additional maintenance work, do to the hours it has been run. Now to remember where in the world did I put the manual!! lol The general oil change, keeping the oil topped off, no problem along with gas removed when not in use.

    The Honda gas/propane generator has set for some time, and it may be beyond my capabilities for repairing it. Hope I can locate the paperwork on it for a deep dive repair other wise I will need to locate the model number. πŸ™„ 😣 It is not uncommon for me to tear something apart to fix, but this. This will be my largest challenge yet, hope it is as easy as tearing apart a VCR to fix and putting it back together again. Shall require a L O T of photos when I start down this road, as I am always being interrupted in the middle of my projects. It may be days to weeks before I get back to what I was working on around here. Oh,,,well! πŸ€—

  11. I have a honda ua 3000 to run the well. I have a harbor freight 1500 as a back up but it is only 110 volt. I have a solar array for the green house. I have a small solar array for charging cell phones. I have 4-5 gallon propane tanks for the BBQ grill. 15 one gallon propane tanks for my little buddy heater, one wood fire place in the living room and one propane fire place in my wife’s office. 15 gallons of ethanol free gas that I will use in my truck this spring if I don’t use it this winter. 1000 gallon propane tank that was just filled for the winter and 4 cords of firewood. Did I mention the sun oven? I did run the honda this summer for several tanks but I guess it would be a good idea to run it again now as Ken suggests.

  12. I use deep cycle marine batteries, which are connected to my 2500 Watt Cobra inverter. The marine batteries are connected to my car’s battery, which is used to charge the marine batteries when needed. The car does not run constantly and the deep cycle batteries are not damaged when you draw them down over 50%. I can run rated power for many hours just off the batteries and power all my refrigeration units…which do not run constantly. For every hour a 16cu.ft.refrigerator operates, it only needs power about 20% of the time. For survival, only the food storage power is important, as every other aspect only requires manual effort to achieve and is not electrical dependent.

    Since the food in cold storage is the first food to be consumed, or cooked, or canned…as soon as this food is no longer in need of cooling, you no longer need electric power…save for running a few fans and possibly a few small led lamps. This means one can keep electrical power in stasis until it is actually required, after the refrigerators are empty. By which time, the Zombies might begin to show up..and the electrical supply can be used for defensive purposes…such as blinding lights, etc.

    Run your house and your car, like a boat…or a diesel submarine.

    1. What problems could be expected by using an inverter on a hybrid auto, such as a Rav4? Is it even possible, without causing damage? Our pickup uses a lot of gas, so the conversion would not make much sense.

      1. Just use deep cycle batteries and not the standard car battery. The inverter will run without the car’s engine running. Use two batteries. The one directly powering the inverter is not your car battery. Your car only recharges the inverter system, when its battery gets low. If you use a large marine battery, it can run your refrigerator for many hours without the car.

  13. When you run your genny dry after testing, and it has a manual choke, wait until the engine starts sputtering and then choke the engine. This will draw out that last little bit of fuel in the carb. Auto-choke units will do this… automatically… This should be done with ANY seldom used engine!

    I was running my gennies once a month, but my smaller unit managed to gum up between tests. I run them for twenty minutes every two weeks now, under load. This “cooks the dust off” both the engine and generator. ALWAYS test your gennies under load! MANY is the generator that loses its output, even though the engine runs fine! ALWAYS top off the tank after testing. This introduces fresh fuel to the system. It also minimizes air in the tank, which minimizes water condensation in the tank, and oxidation of the fuel.

    My 4Kw genny has electric start. I replaced the puny “lawn tractor” battery with a beefy deep-cycle battery. The genny charges the battery when running. I have a pure sine wave inverter connected to the battery. This is for the sensitive stuff that doesn’t like the modified square wave output on the generator. It essentially turns the generator into a generator/inverter generator hybrid.

    I have a Vise-Grip plier attached to the ground cable, which allows me to quickly attach the cable to the ground of my choice.

    If you’re using CPU-controlled devices on your generator,… and this can include things like modern refrigerators, stoves, and other appliances,… TEST them with your generator! THEY MAY NOT WORK if your genny has a modified square wave output! Even your modern GAS stove may fall victim to this. Mine did. The display on it just showed fluttering “rolling 8’s.” Sure; I could light the burners with a match, but the lack of the computer-controlled thermostat rendered the oven useless! Hence, the pure sine wave inverter piggyback on the genny…

    1. TMac,
      Thanks for the advice. I think you are becoming “Master of the Generators”, thanks for sharing your knowledge!

  14. Very good pointers for sure. Just had a test run for two days from Zeta! :)

    I have used 2 year old non-ethanol gas with no problems, not recommending, but I double the stabilizer in my storage fuel. Ethanol in gasoline has cost people a lot in the small engine category. I also use an ethanol treatment just in case the fuel got mixed up in delivery.

    I noticed the comments on inverters and would suggest using batteries rated for solar rather than a deep discharge marine type battery. They are tougher and made to deep discharge without damage, within reason of course.

  15. Wow! Lots of good to great advice here from many people that have a lot of experience. Many thanks to Ken for getting this thread started, Ision for the suggestion of using inverters, Dennis that still has many gas powered tools on his farm. Many others out there that emphasize continuous use and maintenance of gas powered generators. Kula for keeping the limitations of such devices in check.

    My own experience was in using 2 cycle engines in chainsaws and weed whackers. I always ran them dry and stored them dry. I have observed the same practices work well for generators as well. You folks that have generators, Do you keep spare spark plugs around for the generator? Do you have much trouble with the contacts sooting up?

    When I was servicing chainsaws for a wildland fire crew, 50% of the problem associated with not running or poor spark was from spark plug gaps that were sooted up or had varnish on them from being stored “wet” with fuel in the engine and the lines. When we ran them, we ran them hard ( high RPM’s) until the fuel ran dry. As long as the tools were run hard and stored away properly, they ran well and started on the first 3 pulls of the starting cord.

    Also, tools were not abused on the fire crew. ( I have seen angry home owners throw their weed whackers and chainsaws when they cannot get them started ). Hopefully, some homeowner is not going to be kicking or dropping their generator. ( I am sure TmcGyver has some stories for us in this area ).

    I recently watched a movie that many may find enjoyable pertaining to running of internal combustion engines: Ford versus Ferrari with Matt Damon and Christian Bale. Those of us that grew up working on cars, trucks and gasoline engines will find this movie to be truly enjoyable.

    1. I haven’t had issues with plug fowling with 4-cycle engines. ‘Can’t say the same for 2-cycles. If you’re running a 2-cycle genny, DEFINITELY keep an extra plug or two on hand! 2-cycle plugs foul. 2-cycle plugs short to ground. They just… die…

      …And if your genny has a pull cord to start it, keep an extra pull cord in the spare parts kit… even if it also has an electric start… The pull cord will ALWAYS break when most needed…

      1. 2-stroke generators are absolute crap. Tom MacGyver has already explained several reasons why. If this is all you have access to, also be sure to keep an extra capacitor or two on hand. These (sort of) serve the function of an AVR and smooth out the ratty waveform a little. They get hot and melt often. Even at full-chump retail they should be no more than $10.

      2. Oh one other thing on those little 72cc two strokes. The magic number for pull rope length is 1 meter. (nearly all of them come from one factory under numerous brand names). A couple years ago there were a few hot lots with 1.3M ropes. They would slacken at the end of the pull stroke, and if the engine catches just right, the rope can get caught up in the starter cup and yank your arm bad enough to cause injury. If you have a 2-stroke buzz box, measure the rope and cut off anything longer than a meter.

  16. Ahhhh… the sound of purring generators! As I type, I have mine fired up and purring along out there. Fresh fuel with PRI-G added in. They all started first try. That’s confidence building! Now it’s time to top off my ethanol-free fuel supply…

  17. Friend has an older generator for sale cheep. But, its only 2500 watts. Is that good enough for a deep freeze and only a deep freeze.

      1. tmc
        Yes, starts and runs. Somewhere i read/heard a chest freezer needs 3000 watts to start. I can’t remember where. The gray matter is not what it once was i suppose.Thanks for the help.

        1. Look at the plate on your freezer. Some give the power requirements in watts, but most give them in amps. If yours is in watts, then you’re good to go if the watts needed by the freezer are less than the generator’s output. If the requirement is in amps, multiply the number of amps by 110. That’ll give you the number of watts the freezer grabs from a 110 volt line. The plate might have a “start” current and a “run” current. Go with the “start” current when you do the math…

        2. Not unless it is on a 30amp circuit, 2400w @ 120v is about max for a 20amp circuit, some variation but 3000 would trip the breaker

        3. country – A typical 7 cubic foot freezer will inrush to about 8amps (120×8=960 watts). But that is just for a moment. Once running expect 5 amps (120×5=600 watts). At or near sea level you should be ok. At elevation, derate your generator 3% per 1,000′ asl.

    1. Oh yeah; 2500 watts is PLENTY. An easy test; when you go to check out the genny, take your wife’s hair drier with you. Those things pull 15-1800 watts these days. A 1500 watt hair drier is pulling almost 12.5 amps on a 120 volt AC circuit. The 1800 watt drier is pulling a clean 15 amps! If you can run that without popping the breaker on the genny, you’ll be WAY good to go for a fridge or freezer.

      1. Thanks all for the info. The plate says 4.4 amps. It also says mfg 1986, wow i forgot how long we have had it. Generator is mine now.

  18. I actually just did my pm, changing the oil, spark plug and installed new a avr. I use mine every day. I like how you mentioned putting a load on it. I also pmed my backup genset and pmed my chainsaws. Off grid life ain’t easy.

  19. I have Storm Boss 5500 (10hp Briggs). It has a large plastic gas tank on top. During the 2020 Oklahoma Ice Storm my fuel filter (located inside the fuel tank) clogged. Make sure you have spares and the gasket. This filter fits on the end of the fuel shutoff valve and resides inside the tank.

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