Generator Care Generator Troubleshoot

Generator Smoke – Types of Generator Smokes, Causes, and Fixes

A smoking generator makes most owners panic as, at times, you may start your generator and leave it only a moment later to come and find it covered with white, blue-grey, or black smoke. That’s when you start panicking, and questions start to run through your head. But what you didn’t know is, not all generator smoke is terrible. Some could indicate a problem, yes, but some smoke might be caused by something small such as condensation.

You might not worry at the start, and it ends up being an issue later. The smoke doesn’t mean anything for most generator owners until the generator starts to produce a smoke show. Before yours get to this point, it’d be best to be sure if it’s nothing to worry about. The best approach is to troubleshoot the problem.

Let’s digest the problem.

Why Does a Generator Produce White Smoke (How to Fix It)

Let’s assume this; there is a power loss. You take out your generator, start it and hook it up. But before you even start enjoying the power, you see dense white smoke from the exhaust. It might start with some black smoke that disappears after a few seconds as the unburnt gasses escape the combustion chamber. But then there is this vast show-like smoke produces after few minutes. From there, the engine starts running rough, and before you know it, you’re panicking, not knowing what’s happening.

A generator can give white smoke from condensation turning moisture or burning oil. As the generator sits in the cold, there’ll be minor water condensation in the exhaust manifold. When heated, it turns into white moisture smoke that disappears in few minutes. If oil was to find its way into the combustion chamber and combust together with the air-fuel mix, the result is white smoke.

White Smoke from Moisture: If you experience a light smoke blow at the start, that’s normal, and you’d not worry about it. It’s caused mainly by water condensation in the exhaust manifold. When the hot exhaust heats it, you will get the white moisture smoke. It happens when the generator stays cold until the metal parts start to condense moisture near their surfaces.

White Smoke from Burning Oil: What you need to know is that your generator produces a blow of heavy smoke when it’s burning oil, when some enter the combustion chamber and get ignited with the air-gas mix. It can also be blue-greyish smoke, mostly confused as blue smoke we see in cars.

1) Overfilled Engine Oil

The most common reason a generator would be producing a cumulus cloud of white smoke would be it’s burning a lot of oil.

You might have added too much oil into the crankcase or bought the used generator from an owner that wasn’t that mechanically inclined.

If you’re wondering how excess oil can lead to white smoke from the generator exhaust, understand one thing; the crankcase is a cavity where the engine oil sits. The rating parts of the engine sprays the oil to all the other parts.

Since it’s difficult to add oil to the generator unless you have a funnel, some people prefer tilting the generator at an angle to ease the pouring.

When you dip the dipstick from this position, you will overfill it to reach the fill mark. When you set the generator on level ground, the engine oil will be too much, drowning it. It’s possible to overfill the crankcase with double or triple the standard oil capacity.

Because of this, the oil will be too much for the return jets to handle. So, some will find their way into the combustion chamber.

When the oil is burnt with the fuel-air mixture, the results will be white smoke in the exhaust. How big the white cloud of smoke will depend on the amount of oil reaching the chamber.

The pressure buildup inside the crankcase pushes the oil up to other engine parts, including lubricating the piston.

Suppose you allow the generator to continue producing the white smoke. In that case, it might burn much enough to reduce the oil level in the crankcase to intolerable levels for the internal pressures.

How do you fix it?

The good news is, fixing the problem is relatively easy. All you need to do is drain the excess oil. Start by placing your generator on a flat-level surface.

Open the oil drain plug at the crankcase bottom and allow the oil to drain out until you reach the level of full mark on the dipstick.

If you bought the generator use, it’d be best to do a complete oil change. While doing so, ensure that you use the manufacturer-recommended oil weight.

Always place your generator on a level surface when adding the oil and use a funnel; it will help make it easy to direct the oil into the fill hole.

When you check the oil level, it should be at the end of the dipstick thread tube. If it’s pouring out when you open and remove the dipstick, there’s too much oil in there.

2) Blown Head Gasket

The combustion chamber, where the piston compresses the fuel and air before getting ignited and combusting, consists of the engine block and the engine head, the cover. The two are bolted together to create a seal.

But between them is a head gasket that ensures there is enough seal. When damaged, it can get pried or lifted off.

The head gasket can go around the border, or it might have dividers separating the combustion chamber and the engine pushrods or something, depending on your generator engine type.

These engines with divided head gaskets are susceptible to blown gaskets. The damage can happen internally or through to the external, where it will blow the compression air-fuel outside the engine.

Suppose the gasket divider was to be damaged every time the piston. In that case, it will pull the oil moving around the gasket lubricating the pushrods into the combustion chamber using the vacuum state created.

The oil is then combusted together with the pulled air-fuel mix, and that’s how you will get white exhaust flow out.

And as the piston moves up, the positive pressure would blow the compression and exhaust through to the crankcase. That is why you might see the engine oil appearing to steam if you opened and pulled out the dipstick.

The increase in the negative and positive pressure inside the combustion can force the compressed gasses into the crankcase and out through the breather tube or the air filter.

If there is oil leaking from the generator air filter, the chances are, the engine head gasket is blown and needs replacing.

How do you fix it?

Well! You have to replace the head gasket, which is moderately complex. You start by removing the spark plug and remove the bolts holding the engine head. Clean the piston and combustion chamber of the carbon deposits before replacing the head gasket.

I recommend you change the oil as the compressed gasses that might have been forced to mix with the old oil reduced its effectiveness.

3) Worn-Out Cylinder Wall or Piston Rings

If worn-out or damaged piston rings cause the white smoke, you’re a bit of trouble, especially if you’re planning to fix things yourself. It requires advanced tools, skills and it can be expensive but doable.

Over time, the combustion chamber collects debris like the carbon built time. When these black stuff form chunks from all the compressions, they fall.

If the chunks find their way between the piston and the cylinder, they damage it creating crevices large enough to allow hot liquid oil to pass.

The carbon debris can even score the chamber further with time, or the engine might worn out over the years. If that were to happen, you would be forced to get a new generator.

You can replace the chamber, but considering the price of a replacement and the cost of a new generator, they are too close or more.

Checking if the cylinder is worn out should come first before you can access the piston. Remove the bolts hold the crankcase cover, and break the seal to have access to the crankcase sump.

Now you should be able to see the inner workings of your generator engine. Remove the recoil start cord. With the crankcase open wide and the starter wheel accessible, you should have full access to the combustion chamber cylinder.

Slowly turn the starter wheel with one of your hands. When the piston moves down to the crankcase, run two fingers around the cylinder. Try to find any grooves that might be cut onto it – the surface should feel smooth if the cylinder is okay.

If the cylinder is okay, you probably have worn-out rings that are easy and inexpensive to replace. And since you’re already in the engine, you can take the time to inspect three rings on the engine piston.

If the same wear or damage happened with these rings, oil could get into the combustion chamber and cause white smoke.

If the rings are broken, they won’t provide the necessary seal. If the rubber on the last oil ring is worn out, it can’t brush off the remaining oil off the cylinder.

And with the piston moving at high speed, typically at 3600 RPM, a lot of oil can get through to the combustion chamber, get burnt, and produce white smoke.

The best fix is to replace the three engine piston rings. If the rings are okay, make sure the ring gaps are dispersedly spaced; they are no in one line down the piston. If arranged in a straight line, they might leak oil to the combustion chamber and cause white smoke.

Why Does a Generator Produce Black Smoke (How to Fix It)

Another problem that proves to be a nightmare for the generator owners is a generator producing black smoke. It might start straight after ignition or produce it along the way. It gets even worse when the generator engine starts to run a bit rough. I’m assuming that’s why most people search for ‘why is my generator producing black smoke?’

A generator blows out black smoke when it’s running rich, more fuel relative to the amount of air it should receive, which leads to incomplete combustion. It could be caused by a clogged air filter, closed choke, stuck carburetor, or a bad spark plug. It could also be a sign that your generator is running on low-quality fuel.

Understanding how you can troubleshoot the problem can help you know why the generator is producing black smoke, how to fix it, and how to prevent it in the future. Read along.

1) Clogged Air Filter

When troubleshooting a generator blowing black smoke, the first stop is probably checking the air filter for clogging, as it’s the most straightforward remedy.

When your generator’s air filter is clogged, it’ll mean its engine is running rich; the air reaching the engine isn’t enough to support total fuel combustion.

Because of that, the air-fuel mix in the combustion chamber won’t burn completely, thus producing black smoke.

Removing the air filter should be easy, primarily if you use the generator manual as your guide. Mostly, air filter assembly features two metal claps that you can undo to remove the filter inside them.

If your generator’s air filter is discolored, full of debris, or has oil, it would be best to replace it. Test the generator to see if the problem is still there.

2) Poor Fuel Quality

Do you remember the last time you refueled your generator? Did you store your generator with fuel in the tank without treating it with a fuel stabilizer?

If you can’t remember the last time you refueled the generator, or you’re sure the fuel is older than three months, it might cause the black smoke problem. Even if you treated it, but it’s over 6-months since you refueled, the fuel is still low quality.

Allowing gasoline to last in the fuel tank for long goes stale and reduces its quality. With time, the fuel gets oxidized, and it loses its volatile ‘light ends’ critical in ensuring there is proper combustion. Oxygen molecules in the air also consume gasoline additives that allow the fuel to provide optimal performance.

The use of stale fuel can lead to incomplete combustion, and that will produce black smoke. That’s why it’d be best to drain any fuel in the generator tank and carburetor if it’s been over three months old or 6-months after treating it with a fuel stabilizer.

Use ethanol-free fuel and add a stabilizer when storing your generator for more than 3-months to extend its stability to 6-months.

3) Closed or Stuck Choke

If your generator choke is closed or stuck closed, the engine will receive reduced air leading to partially burnt exhaust, which can cause smoke and backfire.

Start by confirming you set the choke to the RUN or CHOKE position before doing anything. If you forgot, then that might be the issue. Rectify it and see if there is any improvement.

If the chock is on, but you’re still getting black smoke, its level is probably detached, or it’s not attached right.

The best place to start is to check its inside to make sure. Remove the air filter and its assembly, which should have a few nuts or bolts. Check where the lapse occurred.

It’s also probable that the carburetor butterfly valve is stuck. It’s caused mainly by stale gas that glues it physically in place.

If that is the case, you need a carburetor cleaner to help loosen the glue. Spray it on the area where the valve is stuck, on the carburetor body. Try to use your fingers to unstuck it or use a pair of pliers.

Don’t forget to spray the cleaner to the carburetor jet and bowl as they might be gummed up too.

4) Dirty or Worn-Out Spark Plug

When the spark plug isn’t producing a strong spark or incorrect spark timing, there will be incomplete combustion, producing black smoke.

When troubleshooting to see if the spark plug is the problem, start by inspecting it for dirt and the gap between the terminals on its head. Use a spark plug wrench tool to detach it from the engine head.

If the terminals are covered in soot, carbon deposits, then it produces spark with insufficient strength for complete combustion or produces it late in the combustion cycle.

You could clean it, but I would recommend you get a new spark plug and use it. These things are relatively cheap.

If you decided to clean it, wipe it down using a rag. You can also remove the carbon deposits by brushing them gently with a bold brush.

Don’t forget to use a gapping tool to ensure that the gap between the two nodes is ideal for spark production. You can consult the generator manual here.

Once the spark plug is clean, reconnect it to its boot but don’t crew it in yet. While holding its rubber boot, place the thread to any part of the engine block or valve cover. Pull the recoil starter gently and watch for sparks.

If there are sparks, you can remove the rubber boot, attach it back to the engine head and make it tight and snug. Reattach the boot and try starting the engine to see if the black smoke problem is solved.

5) Ignition Coil Going Bad

If you’ve cleaned the spark plug and made sure the nodes are gapped right, and you’re still getting black smoke, there is a possibility the ignition coil is going bad. You can try replacing the spark plug entirely to be sure.

Suppose nothing improves, and the black smoke comes with rough idle. In that case, exhaust backfiring, fuel leaks, reduced power output, the gas smell from the black smoke, and difficulty starting the engine, then your generator’s ignition coil is going bad.

Unfortunately, the only way to fix it is to find an ideal replacement for your generator model.

6) Running the Generator in Air-Tight Enclosure

If you’re using a generator enclosure with limited ventilation, this can happen. It can also happen if you bought a shelter for protecting the generator from elements when it’s running.

Restricted airflow reduces the amount of oxygen getting to the engine for proper combustion. What’s more, the restriction can lead to a high-temperature buildup that lowers the oxygen even more. The enclosure will also allow carbon monoxide to build up, thus reducing the left oxygen further.

The best way to troubleshoot the problem is to remove your generator from the enclosure temporarily. If the black smoke disappears, that was the cause of the problem.

If that’s the case, make sure the enclosure has enough vents to allow cold oxygen in and allow carbon monoxide out. It would be best if you never run your generator in a garage or a shade that allows carbon monoxide to accumulate.

7) Carburetor Alterations

If you’re using a second-hand generator, there is a chance the previous owner might have increased the jet holes to increase the amount of fuel entering the engine.

If this is the case, then the generator is running rich, and there’s incomplete combustion that’s producing the back smoke.

Disassemble the carburetor and check for the hole size. Look for alteration signs like improvised edges. If the hose is more significant enough for a small pin to pass through, then it’s altered.

The best fix for this is replacing the fuel jet or replacing the whole carburetor, which should cost you much, especially if you go for an aftermarket piece.

8) High Altitude

When you travel to higher altitude areas than your generator is used to, you’re likely to experience black smoke coming out of your generator exhaust. Luckily, the black smoke produced here is nothing to worry about, mainly if the carburetor stays clean and everything else is tuned upright.

There are low oxygen molecules in high altitudes relative to a given air quantity. That makes the engine run richer, one of the causes of incomplete combustion that leads to the generator blowing black smoke. However, the exhaust smoke should be much lighter, almost invisible.

If you reside in a high-altitude area, it’d be best to consult with the generator’s manufacturer to check if there is a way to reduce the fuel getting to the engine or any tuning suited with high-altitude generator use.

If you’re just visiting the place, tolerate it for a while. There may be a loss of power, the generator might not reach its capacity, but the generator should run okay.

There is also the possibility of carbon buildup on the spark plug and in the combustion chamber. So, be sure to use an engine cleaner and replace the spark plug once you return from a higher altitude.

Summary – Generator Smoke Can Say a lot About Your Engine

Smoke from your generator exhaust can be as simple as moisture smoke, or it could mean there is a problem inside the engine crankcase. Diagnosing the problem right and fixing the issue as soon as possible can help avoid unnecessary expenses later.

About the author

Sharif Gen

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