Generac Generator Troubleshooting; 5 Issues and 25 Fixes

Your life off the grid depends on your generator, unless you have a great set of solar panels and batteries. While that may earn you points for the planet, it is an unreliable power source that adds weight to your vehicle.

This is why most RV owners continue to rely on generators as their primary source of power, and even many people with solar panels carry generators for backup power. Generators are machines, and they’re often run long and hard. This contributes to breakdowns.

Here are a few tips on generac generator troubleshooting and common fixes for portable generac RV generator.

Issue A. Generac generator battery keeps dying

A generator battery is used to provide power to the engine starter. In some cases, the generator battery can provide power to small devices, as well. What can you do if the generac generator battery keeps dying?

Here are several possible solutions.

Troubleshoot 01: Voltage Regulator Solution

The voltage regulator sends power from the alternator to the battery to keep it charged. If the voltage regulator is malfunctioning, the battery cannot receive enough voltage to properly charge the battery. This will cause the battery to drain quickly or simply fail to charge even though the generator is running.

The solution is typically to replace the voltage regulator.

Troubleshoot 02. Alternator

If the alternator isn’t sending enough power to the voltage regulator, it doesn’t matter if the voltage regulator is working properly. You can determine if the alternator is the problem by checking it with a multimeter.

Test the multimeter for continuity. This is where you’re testing for a complete circuit when the switch is closed. 

The continuity test means there is no or low resistance, and this is an indication that the two points are connected.

If the circuit isn’t connected, then the alternator isn’t sending enough power downstream or isn’t sending any at all.

Issue B. Generator runs rough

A generator running rough is surging and then slowing. The surging may follow a pattern or be random. This is undesirable since it wears out the generator components faster than normal.

Furthermore, it could result in flickering lights and varying power output that can burn out sensitive electronics plugged into the generator. On top of that, it can be a warning that the generator is about to break down.

In contrast, a smooth running generator runs at the same, steady speed. This has the side benefit of being quieter than a “rough” generator.

Troubleshoot 01: Carburetor

The first thing to check is whether the carburetor is clogged, since this is the easiest thing to fix. The root cause of this may be that you left fuel in it for a long time.

Some of the ingredients in the fuel evaporated, leaving a thicker sludge that’s hard for the engine to run. At best, it runs rough.

At worst, it will stall. You can solve this by cleaning the carburetor with carburetor cleaner.

You can also put in fresh fuel and see how it runs. Just make sure you’re using the right type of fuel and proper fuel quality.

Note that using poor quality fuel or the wrong fuel can damage the carburetor.

Troubleshoot 02: Carburetor Repair Kit

If cleaning the carburetor didn’t work, you may need to repair or replace the carburetor. This is where a carburetor repair kit comes in.

Troubleshoot 03: Spark Plug

Suppose the carburetor isn’t the problem. Another possibility is that the problem is the spark plug that ignites the fuel. You can check the spark plugs for damage or wear.

The simplest solution is to replace it. This is certainly necessary if you have a porcelain spark plug that’s cracked. The exposed electrode in these cases will see the electrode burn away. If you see heavy carbon buildup on the spark plug, just replace it.

What if the spark plug isn’t obviously damaged or broken? 

You can test it with a spark plug tester. If you see a strong spark from the spark plug, that’s probably not the problem. If you don’t see a spark or a weak one, the spark plug needs to be replaced.

Troubleshoot 04: Fuel Filter Issue

Sometimes the issue is the fuel filter. If the fuel filter is clogged, the generator can’t get a steady supply of fuel. The simplest solution is to replace the fuel filter.

Note that the fuel filter may be the root cause of the problem if cleaning the carburetor didn’t resolve the problem, especially if you had sludge-like fuel in the generator tank.

If you had enough bad fuel in the system to affect both the carburetor and fuel filter, drain the old fuel, clean the tank, and put in new fuel while you replace the fuel filter.

Issue C. Generator won't stay running

Troubleshoot 01: Carburetor

One possible answer is that the carburetor is clogged. That will cut off the fuel flow and cause it to stop running. Bad fuel in the float bowl will do the same thing. Drain the bad fuel, clean it with carburetor cleaner, add fresh fuel and try it.

Remember to use the right type of fuel and good quality fuel.

Troubleshoot 02: Carburetor Repair Kit Solution

Suppose cleaning it didn’t work. That gunk has probably clogged up the ports and small jets inside the carburetor. You probably need to get a carburetor repair kit and replace key components if not the entire carburetor.

This is especially true if cleaning it and running it with clean fuel and filters doesn’t solve the problem.

Troubleshoot 03: Fuel Cap

The fuel cap has a small vent to let air into the tank as the generator consumes fuel. If the fuel cap vent is clogged, the generator fuel tank will experience a vacuum called vapor lock. That stops the flow of fuel into the carburetor.

A simple way to determine if this is the issue is to loosen the fuel cap and run the generator. If the generator runs smoothly, then you know you need to clean the fuel cap or just replace it.

At least you can run the generator without the fuel cap on, assuming water won’t get inside of it.

Issue D. Generator won’t start

When a generator surges, it may run high and then low. When the generator is dying, it starts but won’t continue running. In this section, we’ll discuss things to check when the generator won’t even start in the first place.

Troubleshoot 01: Spark Plug

Assuming you have fuel in the generator, the next thing to check is the spark plug. If the spark plug can’t generate a spark, it won’t ignite and power the generator.

Take out the spark plugs and inspect them. If the spark plugs are damaged, replace them. If they’re covered in carbon build-up, you can try cleaning them and replacing them. However, that may be a sign that the spark plug is cracked and not igniting properly.

You can install it and then try to run the generator, or you can test it with spark plug tester. (If the tester shows it won’t spark, replace it.) If the generator surges or won’t start after you reinstalled the spark plug, replace the spark plug with a new, good one.

Troubleshoot 02: Carburetor

We mentioned that a generac RV generator may run rough if the carburetor is clogged. If the problem is bad enough, then the generator cannot run at all. The fuel lines may be totally blocked. And if there is no fuel flow, there may not be any fuel for the spark plug to ignite.

You can try cleaning the carburetor with carburetor cleaner. You probably need to replace the fuel filter, since the filter is probably clogged with the same residue that clogged the carburetor.

And the fuel itself should be replaced, if you’re trying to run the generator off the fuel that was so degraded that it clogged the generator.

Ideally, you should drain the fuel, clean the carburetor, and then add clean fuel. Then test the generator.

Troubleshoot 03: Ignition Coil

Suppose the problem isn’t blocked fuel lines or spark plugs that won’t spark when tested. The next possible root cause is the ignition coil. The ignition coil sends voltage to the spark plug to spark it when the engine is running.

If the ignition coil is not working, the engine may not start at all. We recommended checking the spark plugs because that’s easier and cheaper to replace. Once you’ve verified it isn’t any of the spark plugs, you can move on to the ignition coil.

We’d advise you to test the ignition coil with an ignition coil tester. Unfortunately, relatively few people have one of these. It is somewhat expensive to replace the ignition coil if you don’t know for certain if that’s the source of the problem. 

That’s why we’d recommend moving on to the other solutions on our list before assuming this is the right course of action.

Troubleshoot 04: Recoil Starter

The recoil starter connects with the crankshaft to turn over the engine. If the recoil starter isn’t working properly, it may not engage the crankshaft and turn over the engine. You can remove the starter assembly to see if it is working correctly. You do this by pulling the starter rope.

The tabs on the pulley and cam should pull on the hub of the engine and cause it to turn. When you release the starter rope, the tabs should retract. The rope should rewind along the pulley.

Of course, if the rope is broken, that explains why the thing won’t start. If the rope won’t rewind, it can’t turn the engine when you pull it because it is already extended.

Troubleshoot 05: Safety Switch

There are safety switches on the generator that turn it off in unsafe conditions. Sometimes safety switches are triggered during normal operation. If the switch is defective, it will prevent the generator from starting up.

You can check this with a multimeter.

Troubleshoot 06: Start Switch

Some generators have start switches instead of forcing you to pull a pull rope to start up the generator. While this is convenient, it also introduces a new way for the generator to fail to start.

If the start switch is broken, you can’t start the generator. The switch typically has to be replaced if it isn’t stuck in the off positon due to grease and debris. You can determine if the switch is broken by testing it from continuity.

The multimeter should show an open contact when the switch is off and a closed contact in an on position.

Troubleshoot 07: Flywheel Key

The flywheel key is a metal piece in the crankshaft that connects with the flywheel when you’re starting the generator. This piece of metal is subject to a lot of mechanical stress, and it often shears.If the generator suddenly stops and won’t start back up, that’s probably what happened.

You can determine if this is what happened by taking the flywheel out of the engine and inspecting the flywheel key. 

The only solution is to replace the broken part.

Troubleshoot 08: On - Off Switch

Is it on? We’re serious. The generator may not start because it is switched off, even if the safety switches aren’t in the way.

On the other hand, the on-off switch can break and keep the generator in an “off” position though you’re trying to turn it on.

You can check this with a multimeter if flicking the switch and trying to start the generator doesn’t solve the problem.

Issue E. Generator leaking gas

A gas leak is a serious problem with a generator. It doesn’t just waste fuel that could be used to run the generator longer. It creates a fire hazard, since fuel leaking beside sparking electronics and heat sources can ignite.

It is also an environmental hazard, since the leaking gas emits fumes and is poisonous to plants. This is why you want to identify and stop gas leaks as soon as possible.

Troubleshoot 01: Carburetor Bowl Gasket

We’ve discussed cleaning the carburetor as a solution to a variety of problems. The carburetor bowl gasket is the point where you remove that part to access it. When the gasket is dried out, it can’t form a tight seal.

This allows fuel to leak out. If the seal is cracked or damaged, it may leak. If you forgot to replace the gasket, you’ll have a fast fuel leak. If the fuel leak is coming from the bottom of the carburetor, the bowl gasket should be the first thing you check. 

If you just cleaned the carburetor and now have a fuel leak, you should check the gasket as the source of the leak. And verify that it is fuel so that you don’t replace parts because you accidentally spilled carburetor cleaner used to clean the tank on the ground.

Troubleshoot 02: Carburetor Gasket

This is another gasket on the carburetor that can dry out, get damaged or be missing. If you’ve been cleaning the carburetor or replacing carburetor parts, check this gasket near the bottom of the carburetor. If you see fresh fuel around it, replace it, especially if you see the leak as the generator is running or soon after it is turned off.

Troubleshoot 03: Float Bowl Gasket

The float chamber or float bowl in the carburetor controls the influx of fuel into the carburetor. As the fuel is consumed, the float drops. That opens a valve to bring in new fuel.

When fuel comes in, the float should rise and close the inlet valve. If there is a leak around the float bowl, this gasket may be the cause.

And in these cases, it needs to be replaced.

Troubleshoot 04: Fuel Line

Fuel lines are hoses. Like garden hoses and hoses in your RV engine, they’re prone to dry and crack over time. They can be damaged, as well, whether cut by accident or worn down when vibrating and rubbing against other parts.

Inspect the fuel lines for cracks. If cracked, do not try to slow the leak with tape; the fuel line should be replaced. You can’t risk a major failure that spews fuel everywhere in a hot engine.

If you’ve had to clear clogs from the fuel lines because of bad fuel, make sure the fuel lines are securely connected to the appropriate points.

Sometimes things leak because we don’t screw in the connectors securely. Or it is as simple as failing to secure the wire retaining clip.

Troubleshoot 05: Fuel Tank

Fuel tanks can leak. This may be a small leak as the container is worn down or rusts. If the fuel tank is showing wear and tear or the material is degrading, replace it.

Minor damage to a fuel tank like a damaged corner is repairable, but it is safer to replace the fuel tank. You don’t want fumes from a leaking fuel tank building up around a generator. It is a fire hazard.

Make sure you properly connect the fuel lines to the new fuel tank or you’ll have a new source of leaking fuel. And before you replace the fuel tank, make sure the fuel on the ground isn’t there because you spilled it trying to refill the fuel tank. That’s generally the cause of fuel around the fuel tank cap.

However, the fuel tank cap itself can’t leak fuel, though the generator will shut off if the cap is so dirty that the unit can’t bring in air to equalize pressure through the hole in the fuel tank cap.

Troubleshoot 06: Primer Bulb

A primer bulb is a bulb you have to push to “prime” the engine in the generator before starting it. It is usually located next to the carburetor. When you push it, it creates a vacuum that pulls fresh fuel into the fuel intake line. That fuel is put in the carburetor to make it ready or “primed” for combustion.

If the primer bulb is cracked or damaged, it will leak fuel when you’re trying to start the engine. Don’t try to repair a cracked or damaged primer bulb. Just replace it.

Troubleshoot 07: Carburetor

The carburetor like the fuel tank is a large container for fuel. Unlike the fuel tank, the carburetor is exposed to high heat and vibration levels. This means it is prone to cracking, warping and breaking. It can also rust. If you find fuel leaks around the carburetor but none of the obvious candidates like seals or fuel line connections are responsible, the issue may be the carburetor itself. 

Check for cracks and corrosion. If you find those, replace the main body of the carburetor. If you’ve replaced every other source of potential leaks and it still leaks, replace the main carburetor. This is especially true if the fuel tank itself has corroded or cracked, whether due to extremely cold weather or damage from being dropped.

Troubleshoot 08: Fuel Shut-Off

Just as the priming switch to start up the engine can leak, so can the fuel shut-off valve. In general, the solenoid that controls the switch is where it will leak. Always replace the solenoid instead of trying to fix it. After all, you can’t afford to take the risk it won’t work perfectly in an emergency.

Note that the leak may be the fuel lines around the fuel shut off valve, so inspect those before you replace the fuel shut off valve. There may be cracks in the fuel line leading to the shut off valve.


The portable generac RV generators are essential to powering life off the grid. They are complex pieces of machinery. However, the most common problems are simple enough that most RV owners can troubleshoot and repair them themselves.

John S.

Hello guys! I'm a 37-years-old author, traveler, writer, blogger, and a camper. I enjoy life as much as I can and love to visit beautiful places in my RV. That's why while traveling I have decided to dedicate some time to share my experiences with everyone that might be interested in traveling, camping, and RVs.