Common Reasons Your Generator Won’t Start

Whether it’s a gas-fuelled giant or a solar-powered portable unit, generators are excellent as a power source at home or on the go. Unless they’re refusing to start, that is. If yours is refusing to turn on, troubleshooting can be tricky.

Because they are intricate machines with many parts, big and small, knowing where to begin with identifying the source of your problem is difficult. Not to worry - we’ve compiled a list of potential causes and possible solutions, just for you.

Read on to discover the most frequent menaces to generator users worldwide, and we’ll advise you on how to solve them. Hopefully, we’ll have you back up and running in no time, and you’ll be prepared should you have this issue again!

We’ll also explain how to keep your generator well-maintained once you’ve fixed the problem, as well as answering some FAQS at the end. We’ve picked the most common customer queries to answer, so maybe you’ll find a response to yours, too!

Why won’t my generator start?

The Battery Is Flat

Alright, we’re starting with the most obvious, but you’d be surprised how many folks don’t think about this one. Even if you remember it being fully charged, a portable generator can deplete in battery power if it goes unused for a long period of time.

If it’s the generator’s starter independently that’s battery-powered - this is usually the case when there’s an electric push-button or remote - it could be that this has run down. Try using the auxiliary recoil (manual pull switch) to start it up, if there is one.

Should you succeed in activating the generator this way, charging the starter’s battery via a 12 volt DC charger - much like the outlet in your car - or find a converter so you can make use of your home AC outlets.

In an emergency situation, you could always jump-start the generator’s battery using cables connected to your car. Failing all of the above, it’s likely that there is another root cause of your problem. This doesn’t mean there isn’t a battery issue though!

The Tank Is Empty

Again, possibly something you’ve already checked, but we’d be remiss if we didn’t point out that your generator may be lacking the necessary juice to kick-start. On propane powered units, you should double-check the necessary valves are open too.

It’s worth remembering that old gasoline (which is generally considered stale after approximately two months) can damage your engine, specifically the carburetor. If you’ve put old fuel in your generator, you must thoroughly clean before refilling.

All Out Of Oil

As well as fuel, your generator depends on oil to properly run, which is why the majority of contemporary models are equipped with a sensor that detects when your unit is running low. This forces an automatic shutdown to preserve the engine.

Using a new generator for more than twenty hours in a row, or an older one that hasn’t had an oil change in more than fifty hours of consecutive use, then this could be the culprit of your start-up issues.

Find your generator’s dipstick, commonly placed in the crankcase, and check how much oil you have. Should there not be enough, find out which engine oil is appropriate according to the manufacturer’s instructions, then top up that tank.

Engine Flooding

Another fairly common ailment for generators is a flooded engine: essentially, excess fuel gathers up, unburned, in your combustion chamber. This means that your spark plug is damp and cannot function properly, rendering it useless to ignite and start.

Don’t continuously yank at the recoil (manual) starter or repeatedly press the electric on switch, as this will only make things worse. You need to open up the air filter and allow excessive fuel to evaporate for a while, then wait and try again.

Again, there’s no guarantee that this is your issue, it’s just one of many on this list that you can try out. Hopefully we’ve provided enough solutions that at least one of them will work out for you!

Defective Ignition Coil

Working to provide a voltage to the spark plug once you start up your engine, a defective coil can prevent start up altogether. We highly recommend you check your spark plug is working using an appropriate tester first.

If you can rule out the spark plug as an issue, then get yourself an ignition coil tester and find out for sure if this is stopping your generator from properly switching on. They’re fairly easy to replace, so don’t worry if you have to!

Choke Needs Adjusting

The mechanism responsible for controlling how much air enters the carburetor as your engine ignites, the choke is an important part of the start-up process. It could be that there is a surplus or not enough airflow, which is preventing combustion.

When your generator is being activated after a few hours (or more) of rest, you’ll need to completely close the choke. This position is usually marked as the starting spot for the choke on generators, whilst opening up aligns with the marker for ‘run’.

Restarting the generator immediately or not long after it has already been running means combustion will occur more easily, so the choke should be set at half-way or fully open in order to successfully ignite.

Blocked Air Filter

Did you try adjusting the choke, only to find that it appeared to improve things, but not completely fix the problem? If there are dirt, dust, and other particles blocking up your air filter, it’s possible that the carburetor isn’t receiving enough air.

This prevents proper combustion from taking place. You’ll be able to easily access and visually assess the filter to see if this is the case and replacing it may solve your problem altogether!

Faulty Spark Plug

Have a look at your spark plug: is it showing any wear and tear or more significant damage? For example, if you notice a great deal of carbon buildup at the electrode, or the electrode itself appears to have burned away, replace the whole plug.

Similarly, if you also notice the insulating material - usually porcelain - is damaged or marred in any way, this also calls for a full replacement. It’s easy enough to test whether your spark plug is the problem using a testing kit.

When you crack the engine up at ignition, there should be a strong and visible spark between the two testing terminals. If this is not present, you can bet that the issue is with the spark plug and not your generator itself.

Clogged Up Carburetor

Did you fail to drain your carburetor before putting your generator away for long term (more than a month) storage? Stale gasoline creates clogs as it festers away, preventing fresh fuel from reaching the carburetor for combustion.

First, you’ll want to completely close your fuel valve, so you can detach the bowl from the bottom of the carburetor. Using a small brush (sacrifice an old toothbrush if you have to) and a large rag, carefully unclog any lingering fuel clumps.

Being super gentle, you should also utilize a sewing needle or drawing pin to delicately clean out the tip of the jet nozzle. Open up your fuel valve before you attempt start up again, or you definitely won’t succeed! 

Fuel Line Or Valve Trouble

When your carburetor is in full working order, and you definitely have plenty of gas in the tank, it could be a problem somewhere in the fuel line or with a valve itself, which determines the rate fuel travels and where it goes.

Ensure that the fuel valve is definitely pointing at open - if it is, and there still doesn’t appear to be any fuel movement, there are a few steps you can take. Does your gas tank have a vacuum relief valve? First things first, you want to open that up.

Then you need to disconnect the outlet hose from the fuel intake side of the valve - make sure you have a bucket ready, as gasoline may begin to freely flow! By doing this, you should be able to figure out where that blockage is and dislodge it.

Malfunctioning Sensors

Remember that handy low oil malfunction sensor we mentioned earlier in the article? Yeah, as helpful as it may be, it could also be the source of your stress if it isn’t working as it should! When faulty, it will prevent startup even if your oil tank is full.

You should first check that your generator is placed on a flat surface, allowing it to stand properly. Uneven terrain can cause your meter to read incorrectly, so it might not be broken, just misreading because of where you’ve put it.

In order to troubleshoot this issue, first disconnect the sensor - you will likely find the wire for it exiting the engine’s crankcase - and then try switching the generator on. If it starts, you know the sensor is your problem!

It could be that once reconnected, if you run the generator for a couple of minutes, the sensor will reset itself and recognize the correct amount of oil. If this is not the case, it’s clear you’ll need a replacement. These are difficult to find and install!

Whilst disconnecting this sensor is absolutely fine when you’re checking for any issues, under no circumstances should you do that to prevent the generator from detecting low oil. This can cause serious damage to your engine and is dangerous.

It’s Just Too Cold!

Sometimes, a generator hasn’t been built to withstand the temperatures of winter and succumbs to the cold. Whether you’ve pulled it out after a season of storage, or you’re dusting it off in the middle of Christmas, perhaps it’s simply too chilly.

Most contemporary models have a pre-heat setting that you can use before you attempt full ignition. They’ll usually tell you when things are ready to rock and roll with a small glowing light, preventing this false start frustration.

Ensure you keep a generator sufficiently covered up when you put it away for a long period of time, and always give it a few hours to acclimatise before you attempt to run it. Performing a thorough maintenance check after storage is also advised!

How can I keep my generator running smoothly?

Hopefully, our above tips and tricks will help you successfully troubleshoot any problems your generator is running.

But, once you’re back in full working order, how can you guarantee you’ll keep it that way?

We’re here to help with that too!

Invest In A Quality Model

Okay, it might be a bit late if you already have one and it’s not very good.

But the best advice we can give? Do your research, and select a quality generator that other customers can vouch for.

You’ll be glad you spent your time wisely in the long run.

Power Up Every Couple Of Months

Yes, even if you don’t intend to use your generators, manufacturers would advise switching it on for a half hour so you can charge the electric starter’s battery.

This will usually stop you from finding it dead when you actually need power!

Only Fill With Proper Fuel

Ensure your generator always has plenty of fuel ready to go, and never stray from the power source your manufacturer recommends.

You could damage the engine and even put yourself at risk of safety hazards. It just isn’t worth it. 

Oil And Filter - Full and Fresh?

As with the above, you also want to make sure your oil and air filters are fresh and in full working order on a regular basis.

If anything, this will help you to avoid coming to use your generator and finding it won’t start up properly. 

Store It Properly

This point is worth repeating. Your generator needs to be stored in a cool, dry place.

It should preferably be elevated and away from the floor, as this will minimize the impact of dust and dirt.

Covering with tarp, at the very least, is recommended.

Use Our Checklist

Whilst you’re at it, you might as well perform a routine examination of all of the key components we mentioned above in our troubleshooting guide.

This will help keep everything in tip-top condition for much longer.

Your Best Friend - The Warranty

Again, a little difficult if you’ve already had your generator for years, but hey, at least you know for next time!

Purchasing a model with an included warranty, the longer the better, ensures you’ll have manufacturer support should you encounter any issues.

Avoid Overheating

If it isn’t necessary to run your generator for a long period of time, try and give it a rest between bursts.

Leaving it on for longer than required can run it down after a while, and you’ll find it becomes less efficient over time. Give it short breaks!

Follow NFPA Testing Guidelines

According to the National Fire Protection Agency, you should be testing your generator at 30% - 40% of their maximum load for half an hour a month, at least.

Read about that, and other standards for generator owners to follow, here.

Frequently Asked Questions

How long can you run a generator continuously?

That depends on what kind of generator you have! A portable model is only going to get you as far as a few hours to overnight, maybe a few days if it’s higher-end. For serious long-term use, it’s got to be a standby unit.

Because they are built with larger, more powerful motors, purpose-made for coping with continuous use, you’ll find they offer weeks of run time. Three weeks to be exact, which comes to approximately five hundred hours.

Whilst these estimates of use are appropriate to apply to most contemporary generators, you should always observe your units and look out for signs of overuse. If you can afford to turn it off for a while and allow it to rest, you’ll have it for longer.

Why does my generator only run on choke?

According to our research, if the generator stalls or falters after you turn the choke down or off, it’s likely you’re failing to hit the optimum combination of fuel relative to air. Your issue could be one of several, the first being a clogged carburetor.

It could also be a result of a clogged pilot jet, ‘stale’ fuel, leaky valves or gaskets around the carburetor area. Either way, you’re failing to achieve proper combustion without the choke fully open.

Advice suggests that using stabilizer to clean up your gasoline (if you haven’t already) is your first best bet. Then you’re going to want to switch off your fuel valve to drain out your carburetor, so be ready to catch that fuel!

Carefully scrape out any oily, tacky residue on your carburetor, and follow the guide above for our advice about removing any clogs! Hopefully once everything’s had some TLC, you’ll be back up and running again.

What are the symptoms of a bad carburetor?

If your generator’s got an issue with its carburetor, you’re already going to know about it, because of a reduced engine performance. This will be evidenced by a reduction in overall performance and efficiency of fuel use.

You may also notice the exhaust begins to leak a dark, black smoke, excessively burning fuel to the point where toxic emissions are being produced. These are antithetical to the generator process and actively harmful - a big no-no!

When you’re experiencing consistent overheat and automatic shutdowns, or a ‘backfiring’ of the engine, where it appears to start only to stall again, this can also be indicative of a carburetor issue.

Trouble with starting up, as we suggested earlier in our guide of common generator faults, also suggests a faulty or clogged carburetor. Whilst they could also be symptoms of other issues, checking out the big C should be your first port of call.

What are continuous, prime and standby power ratings?

When it comes to generators, a standby model (as we define above), is usually reserved for emergency scenarios, for instance a power cut in your home. You are advised to use it only for as long as the outage lasts, and test it regularly.

Comparatively, a prime power rated generator has what is considered a permanent or unlimited runtime - this can be used as your primary source of power, instead of serving as a back up in case of emergencies. They also work off-grid!

Similarly, a continuous power generator can run for as long as you like to a constant load, but it can’t deal with overloading and will only be able to generate a specific amount of power. 

The primary difference between continuous and prime power generators is that the latter typically provides a variable load for an ‘unlimited’ period of time, where the former can manage as much power as you need it to produce, and then some.