A Guide to Portable Generator Maintenance

Whether you are a new, or an experienced portable generator user, a daunting thought may have crept up your mind. “Am I taking the best possible care of my (expensive) generator?” How could you possibly tell?

It seems to run just about fine… until one day, it doesn’t. And at that point, it’s too late. Follow along to avoid just that.

Regular maintenance is the key to a long-lived, healthy portable generator that will continue to provide you power for years on end. On the other hand, neglecting maintenance duties will result a generator rapid deterioration.

Taking proper care of your generator is always cheaper than buying a new one. However, even though you may understand this intuitively, you might have no idea where to start, or how to go about maintaining your portable generator properly. In this article, I’ll introduce you to the topic of portable generator maintenance and give you some tips and tricks to help you along the way.

Note: Throughout this article, we will give you general guidelines on how to and how often to perform the most important maintenance tasks. Each paragraph will begin with the following two icons: The tool icon which indicates the recommended equipment, and the calendar icon which indicates the recommended frequency (of carrying out the task).

The Basics of Portable Generator Maintenance

To get our lingo straight, generator maintenance is a set of routines which aim to ensure peak performance of your generator. These tasks include everything from inspection or changing your oil, to cleaning tubes and checking the engine.

Unless you’re an engineer, you may feel threatened by these tasks. Don’t worry, you’re not alone. As with a car, or in fact, any other device, there is a clear line between the regular, everyday tasks and those that should be performed only by experienced mechanics. Both we and generator manufacturers understand that.

The following section will focus only on the former, the tasks to be performed by you, the user. As a rule of thumb, all parts easily accessible to the user are maintained by them (oil, fuel, spark plugs, etc.) and vice versa, all parts which are not (engine, electronic circuits, etc.) are to be maintained by a professional.

Before we start, we urge you to refer to your user manual. Consider it your own Generator Bible. Every single portable generator comes with one and is the best source of information on how to go about using and taking care of your specific model.

Maintenance Schedule

All user manuals contain a chapter dedicated to maintenance, in which you will find a maintenance schedule. This schedule contains a list of all maintenance tasks that are recommended to be carried out periodically, along with the respective periods. Also, information on which tasks are to be done by the user and which should be handled by a professional is included (see examples below). Make sure to add the dates of these future maintenance checks into your calendar, since they are easily forgotten.

Here are a few examples of maintenance schedules:

Maintenance schedule of the Honda EU7000is

Schedule of the Honda EU7000is

Maintenance schedule of the Westinghouse WGen5300v

Schedule of the Westinghouse WGen5300v

Maintenance schedule of the Champion 100165

Schedule of the Champion 100165

Maintenance schedule of the Generac GP2200i

Schedule of the Generac GP2200i

Maintenance Reminder

Many portable generators also feature a maintenance notification (reminder, etc.) system directly in their control panel’s data center. These are typically oil change reminders, but various others may be included, such as a notification to replace your air filter.

Take note that as seen in the example below, these systems are often not regulated by e.g., the current oil levels, but simply trigger after a certain period of time has elapsed. In such cases, it is still necessary to perform an oil check before each use, as specified ahead in this very article.

VFT meter with maintenance reminder

This kind of maintenance reminder can be found on several models, including on some Westinghouse generators

Maintenance Kits

Maintenance kit for Honda EU7000iS generators

A maintenance kit for Honda EU7000iS

Some manufacturers or third-party retailers offer so-called maintenance kits, which usually include commonly needed spare parts (air filter, spark plugs, etc.), oil and possibly some tools for disassembly or even cleaning equipment.

All parts included are often also sold individually for a lower price, so in general, I recommend going for one of these kits only if you’re getting a better deal.

As a rule of thumb, try to stick to OEM parts.

CO Sensors

Generac COSense

Generac COSense®

Any additional instruments which are part of your generator, namely CO sensors, have their own maintenance requirements which must be attended to, to ensure their functionality.

A CO sensor may or may not have its own notification mechanism, which is usually based on the frequency of its flashes (not unlike common smoke detectors), that will indicate the approximate end of its lifespan.

If your device contains a CO sensor, do not forget to study your manual for these additional instructions and adjust your maintenance schedule accordingly.

General Inspection

Just your senses
During each use

When it comes to determining which maintenance tasks should be performed when, the maintenance schedule is a great starting point, but it’s not a be-all end-all. Air filters can get clogged up faster than expected, spark plugs can die off sooner, etc. It’s up to you to tell when is the best time to grab your tool belt and get things done.

Above all, some maintenance schedules leave out many other essential tasks, such as cleaning, tightening up screws, making sure your outlets aren’t dusty/dirty, taking care of your extension cords, electric starter battery replacement, etc.

For these reasons, it is best to take a few minutes to perform a quick inspection ALWAYS before or after you’re done using your generator. This will ensure that you’ll have a very good idea of how well your generator is running, if there may be some issues that require your attention, and in case your generator is damaged, a thorough inspection will alert you to the fact before the fault gets out of hand.

So, how to go about inspecting your portable generator? As any engineer will tell you, inspecting any device is like an interrogation. Your success depends on asking the right questions. Below are a few examples, but feel free to also refer to the pre-use inspection checklist from Harvard University (opens in a new tab).

Is my generator running as it should, e.g., handling the load well, not dying, etc.?

A dying or progressively less efficient engine is usually a sign of engine issues, insufficient rate of fuel injection, etc. These issues require assistance of a professional.

Do I have an unusual, or progressively worsening trouble starting my generator?

If so, you probably should have changed that spark plug, or the battery in your electric starter, some time ago.

Are all of my generator’s screws and bolts in their place and tightened?

In general, it is a good idea to replace/fix any loose or missing screws and bolts, before the entire generator starts falling apart.

Are there any signs of cracks or damage on the body of my generator?

As mentioned above, any mechanical damage should be repaired ASAP to prevent it from spreading.

Does my generator sound as it should when it’s under load?

While it may be hard for an inexperienced user to trouble-shoot based on sounds alone, an off-sounding generator will at least help you tell when it’s a good time to visit your mechanic.

Do all of my generator’s buttons work properly?

A loose, broken or ill-fitting button is much easier (and cheaper) to replace than the circuit it sits on, which may become damaged over time as you are forced to push it, twist it, and quite possibly hit it progressively harder in despair to achieve contact.

Does my generator leak oil or gas?

Many areas of your generator can leak both fuel and oil, both of which are a huge safety hazard and require professional assistance.

Are all my extension cords in a good condition?

Surprisingly, whenever you are experiencing any power issues, such as “there is no power”, the most likely explanation is that your power cords are damaged due to twisting, bending, etc. This can be easily diagnosed by checking the condition of the entire length of the cord, which should be sealed and stiff throughout. In addition, this procedure will alert you to any exposed areas of the cord, which in worst-case scenarios may and often do lead to electrocution.

Is there any unusual smell coming off my generator? (typically smell of burnt toast)

As is the case with any engine, smell of burnt toast is a typical sign of carbon buildup. Carbon buildup reduces the efficiency of your generator and in extreme cases, may cause permanent damage and can even be a fire hazard. Do not delay getting rid of it if this is the case.

Are all my outlets clean and do they have good contact (plugs sit tight and are under current at all times)?

Dirt and dust may obstruct electrical outlets, leading to poor, or in severe cases even no contact. This can be easily fixed by proper cleaning.

Furthermore, an entire socket, or its innards may come loose. This may require you to tighten a screw, but in cases of more complex damage, will require professional attention. Both of the two “socket” related issues tend to get progressively worse.

How to Perform Regular Maintenance Tasks

Adding to what we have already mentioned, I present to you a short guide to some of the most common generator maintenance-related tasks. While most of these are pretty universal, apart from a few exceptions which will be pointed out, always consult your user manual before attempting any of the following procedures and prioritize the instructions within, rather than whatever you may have read on the internet (including here).

Cleaning

Water, soap/detergent, coke, brushes (preferably also tube brushes), a can of compressed air, a piece of cloth, a rag
Before or after each use

The most basic, but by us guys often overlooked maintenance task, is cleaning your generator.

Follow the user manual for any cleaning guidelines. In general, disassemble your generator according to the manual, avoid applying any liquids to electronics. Clean both exterior and accessible interior of the generator unless specified not to by the manual. Do not force your way into any parts, as that may void your warranty. NEVER USE A POWER WASHER, NOR A HOSE!

Remember that whenever you are disassembling, assembling and replacing parts of your generator, all surrounding areas should be cleaned and left to dry to avoid contamination of the generator’s interior, which may lead to permanent damage.

There are many ways to go about cleaning, which will depend on the surface, area and the type of stains encountered. Since I cannot presume to predict every stain on every generator, I will do my best to lay out general cleaning guidelines, along with some nifty tips and tricks, which should be applied on a case-by-case basis.

Common Solvents

Most areas of your generator, especially its exterior, are best cleaned by water and soap. Common detergents can be used too, as they often have enhanced cleaning properties. For less polar stains, rubbing alcohol, toluene or other paint thinner/removers are the last option.

After performing your cleaning duties, let the unit sit and dry thoroughly before starting it again or plugging it in. Avoid applying water to electronics and think twice before applying any solvents to the painted areas of your generator.

Coke

To the surprise of many, coke is perfect for dissolving tough-to-clean stains and larger chunks of dirt. Coke may be used on any part of your generator that can be taken out and submerged in it for a day or two.

Cleaning Apparatus

With solvents out of the way, now you’ll need something to clean with. When picking cleaning tools, one should weigh his options carefully, as the surface of your generator is surprisingly delicate. Trust me, I learned this the hard way.

Our preferred choice, applied everywhere, is a cloth or a rag, since they cause the least damage to the surface. It is always better to use them damp, or wet, rather than soaked.

Any tougher stains and carbon build-up may require a bit of a scrub, for which you will require a brush. It is preferable to always go for the softer kind. Tube brushes will do miracles in cylindrical areas, such as exhaust pipes and tubes.

As for electronics, which may be especially relevant in the case of inverter generators, but also for cleaning air filters, use a compressed air can first rather than applying any liquids.

To top it all off, here are two secrets that will blow your mind.

An Extra Soft Toothbrush

Believe it or not, I and many others have found that toothbrushes are the most versatile cleaning tools available on the market. They reach tough-to-clean areas effortlessly, they easily absorb cleaning reagents and are great for intensive rubbing. To top it all off, their price is a joke compared to specialized cleaning equipment.

A Kitchen Sponge

Instead of cloths, you may opt for a kitchen sponge. They are great for cleaning the exterior of a generator, but they will do equally fine anywhere they reach, as they absorb large volumes of cleaning agents and have a textured, but soft surface. Just make sure to scrub off larger chunks of dirt first.

Oil Check and Replacement

Oil, a funnel (optional), a dipstick, possibly tools for disassembly (screwdriver, etc.)
  • Oil check: Before or after each use
  • Oil change: Every 50-100 hours of use, or 3-6 months when idle. Special conditions apply when breaking in your generator

Simply put, running your generator dry, that is, without oil, will cause havoc to its engine. Some generators will alert you and shut down before that happens, but even if they possess such capabilities, if that happens while you’re busy working, watching your TV, or whatever you may be using your generator for, you’ll probably regret not checking and refilling your oil sooner.

When it comes to oil checks and changing your oil, rules apply:

  1. Before each use, check your generator’s oil level.
  2. After every 50-100 hours (exact intervals are specified in your user manual), change your oil regardless of the oil levels.
  3. If you haven’t changed the oil for 3-6 months, change it regardless of how long you’ve been using the generator.

Both procedures are explained in every user manual and can differ a bit from generator to generator.

Generac dipstick

A dipstick made by Generac

In general, oil checks are performed by shoving a dipstick into the generator’s oil-filler neck. We recommend you use whichever dipstick was provided by the manufacturer.

Changing oil requires you to drain whatever oil is left in the generator while the oil is still warm. If your generator isn’t warm, run it for a few minutes before proceeding further, unless running is prevented by low oil levels. To drain the oil, use the oil drain, which should not be confused with the oil filler, as they are two different holes! Help yourself by leaning the generator to make sure that generator is empty. Only then proceed to fill the generator with oil. Make sure to never overfill.

Lastly, if you are an owner of a new generator, you should follow the correct break-in procedure, which will require you to change the oil more often.

Cleaning and Replacing Air Filters

A piece of cloth, a kitchen sponge, a can of compressed air, cleaning liquid of your choice, possibly tools for disassembly (screwdriver, etc.)
Every 50-100 hours of use, or as needed (e.g., more often in dusty conditions)

An air filter’s purpose (opens in a new tab) is to avoid anything from getting sucked into your generator. Simply put, anything solid gets caught in the filter, anything gaseous travels straight through it.

As such, layers of particles will build up on the air filter over time. The build-up will have a negative impact on the air flow and hence the generator’s functionality, e.g., anything gaseous will no longer travel straight through the filter. For this reason, air filters must be cleaned periodically and eventually replaced.

Honda generator air filter assembly

Honda generators often have both a foam and a paper air filter

BEWARE: Some generators also feature paper air filters which cannot be cleaned and must be replaced right away! Check the user manual if this is the case of your air filters as well, before proceeding further!

The simplest way to clean an air filter is by using a can of compressed air. Remove the filter and use the can in the opposite direction of the usual airflow, at close proximity, blowing through the filter itself. This will remove most of the build-up.

A more invasive method involves soaking the air filter in a bucket of soap water, or alcohol (in this case, not coke!) The filter’s surface may be CAREFULLY scrubbed if necessary, with a piece of cloth or a kitchen sponge, never a brush!

Some manufacturers (e.g., Honda) recommend dipping the air filter in fresh engine oil as well. Consult your user manual before doing so.

Keep in mind that regardless of how well and often you’ll clean your air filters, they will eventually wear out. Always keep a few replacement filters around.

Honda generator foam air filter cleaning guidelines

Honda foam air filter cleaning guidelines

Spark Arrester and Spark Plug Service and Replacement

A spare plug/arrester, a small wire brush, a feeler gauge (wire-type works well), tools for disassembly (screwdriver, spark plug wrench, etc.)
  • Cleaning: Every 50-100 hours of use, or as needed (e.g., more often in dusty conditions)
  • Replacement: Every 300 hours of use, 1 year when idle, or as necessary, based on their condition

Spark arresters and spark plugs require regular maintenance, and quite commonly also replacing. Make sure to always keep a spare plug/arrestor around.

Cleaning of spark arrester

Use a wire brush to remove carbon deposits from the spark arrester screen

Servicing both spark arresters and spark plugs requires removing the part as specified in the user manual and cleaning both of them and the area around them. From my experience, this is best done using a small wire brush. No liquids nor cleaning agents are usually required, though deeper cleaning may be necessary in some cases.

Remember to always stick to the spark plugs and spark arresters recommended by your generator’s manufacturer.

Spark arresters must be carefully cleaned and checked for damage. If they are damaged, broken, or torn, they should be replaced right away.

Spark plugs must be carefully cleaned and checked (opens in a new tab) more thoroughly for damage, most importantly their electrodes, washer seal, and the size of their spark plug gap, between the main and side electrode. If any damage is detected, the spark plug must be replaced.

Feeler gauge checking the spark plug gap

Checking the spark plug gap with a feeler gauge

The spark plug gap is checked by a feeler gauge (opens in a new tab). The gap should stay within the range of whatever is specified in your user manual, usually somewhere around 0.027-0.032 in. The gap can be manually corrected by bending the electrode carefully if necessary.

Spark plugs must be reinserted first by hand and then tightened by a spark plug wrench. Some manufacturers even add details as to how many times the spark plug must be threaded. However, the golden rule is to NEVER LEAVE THE SPARK PLUG LOOSE!

GFCI Check

A finger, possibly a lamp
Before each use
GFCI outlet

A GFCI outlet
Source: cat.com (opens in a new tab)

If your generator is equipped with GFCI (ground fault circuit interrupter) outlets, it will require a regular inspection as well.

Testing GFCI functionality involves tripping the ground connection using a dedicated test button, and monitoring if the circuit is interrupted. Some generators require you to plug some appliance into one of the receptacles, such as a lamp, to see if it switches off, while other models use simple LED indicators. The specifics of such test will be described in your generator’s manual.

If you find that your GFCI does not operate properly, ensure that your generator is properly grounded. If it does not resolve the issues, do not use the generator and seek out professional assistance!

Servicing an Electric Starter

A spare battery, a charger, possibly tools for disassembly (screwdriver, etc.)
As necessary

Generators with an electric starter include a battery which must be checked, recharged and if it leaks or no longer holds charge, replaced. Always use batteries and chargers recommended by the generator’s manufacturer.

Changing a Fuse

A spare fuse of the correct rating, possibly tools for disassembly (screwdriver, etc.)
As necessary

Though the following section is related to troubleshooting rather than maintenance, blowing a fuse is quite common and for this reason, fuse replacement will be addressed in this article as well.

All generators contain either a circuit breaker or a fuse. While tripping a circuit breaker simply requires you to reset it, fuses must be replaced as specified in the user manual. Other than that, fuses do not require periodic checks.

Keep in mind that each fuse services one circuit and thus is rated for the circuits amps. For this reason, make sure to keep around fuses for all ratings provided by your generator and always replace fuses with those of the same rating.

Checking Valve Clearance

Feeler gauge, possibly tools for disassembly (screwdriver, etc.)
As necessary

Maintaining proper clearance of the generator’s engine’s intake and exhaust valves is required for its unobstructed functioning. It is recommended to check the clearance every 50-100 hours. Based on the model and your confidence, clearance can be adjusted either by you, or by an authorized professional – the process can be quite simple, as seen here (opens in a new tab).

Note: Perform this inspection only on a cool engine.

Locate the intake and the exhaust valve (use your manual to do so). They are usually found next to each other, obstructed by a cover. First, remove the device’s spark plug to easily rotate the engine without starting it. Only then remove the valve cover and position the valves as instructed by the manual, so that the valve’s stem upon which you ARE NOT operating is compressing the spring beneath it. Insert the feeler gauge in between the uncompressed valve stem and spring to check the diameter and compare to the value recommended by the manufacturer. Keep in mind that both too loose and too tight valves are an issue.

Conclusion

With all of the above covered, you are well equipped to handle regular portable generator maintenance. The list of tasks which must be performed may seem exhausting at first glance, but you’ll soon find that performing all of them takes just a minute or two. Consider that time well spent, given how much it trouble it may save you in the long run.

Whenever you find yourself in deep waters, don’t be ashamed to contact a professional. Make sure to do so as well regarding the uncovered parts of the maintenance schedule, to keep your portable generator in the best condition.

Always remember to check your user manual for the specifics of your model and feel free to comment below if you feel that we’ve left anything out!

Paul

Paul

Manager & Editor of generatorbible.com. Early retired from the OPE industry, living in South Carolina. He now mostly spends his time traveling and taking care of his wife and grand-children.

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