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Power Hacks: How to Diagnose Portable Generator Issues

You rely on your portable generator, so it should work when you need it.

There’s nothing more frustrating than a generator that doesn’t run well or is difficult to start. Even the best models can malfunction so it’s handy to understand the basics about operating your generator.

Here are some of the most common generator problems and troubleshooting tips to help you get back up and running fast.




Check for Fuel Problems

Insufficient, Degraded or Wrong Fuel

One of the most common causes of portable generator failure is insufficient fuel, especially if the last time you used your generator was more than a year ago. Fuel level gauges may not always be accurate and some generators are equipped with a ‘low fuel level shutdown’, so always check the levels as a first step.

If your generator has been sitting unused for a while, check its fuel quality. Fuel can degrade while in storage, so stale fuel may need to be drained and replaced. If stale fuel has clogged the engine, you may need to consult with a mechanic for portable generator repairs. It’s also essential that you use the recommended fuel type for your generator (petrol or diesel).

Fuel Delivery or Leaks

If the generator is difficult to start or runs rough, it may have a fuel delivery problem. This usually occurs when the carburetor isn’t getting the fuel or the fuel pump needs to be cleaned/replaced. Leaks in older generators are also common, so check valves and lines to ensure the fuel is held properly in the engine.


Check Oil Levels

Low oil is a common cause of generator engines failing to start. Some will have a ‘low oil shutoff sensor’ to prevent damage to the engine when the oil level is too low. These sensors may also have degraded in older generators, so it’s always best to check if unsure.  Replace oil regularly.


Clean the Carburetor

The carburetor is responsible for mixing the air and fuel together. It sprays a fine mist which is a mixture of the two into the combustion chamber. Once this is compressed, the spark plug releases the spark to ignite the air and fuel mixture. Generators that don’t start or run well can be a sign that the carburetor is clogged.

If you’re cleaning it yourself, make sure to take pictures of where all the parts go before you start disassembling them. Simply spraying cleaner into the carburetor won’t fix the problem. You will need to take all the parts out and clean the carburetor properly. Because carburetors are a sensitive generator part, it’s recommended not to attempt this unless you know exactly how to put it back together again. Carburetor problems can also cause the generator to leak fuel.


Make Sure the Spark Plugs are in Good Condition

Petrol-fuelled generators will have one or more spark plugs to ignite the mixture of air and fuel inside the combustion chamber. If these spark plugs aren’t in prime condition, the generator won’t start. Spark plugs are inexpensive and easy to replace – refer to the manual.

Spark plugs that are coated with thick oily liquid is a sign that the generator isn’t getting enough oxygen and too much fuel. If the oil residue on the plugs looks white or tan in colour, this means it could be getting not enough fuel and too much oxygen.


Avoid Generator Overloading

Overloaded generators will struggle to produce enough power. This tends to be a result of running too many devices. To test whether this is the problem, switch off all appliances and run the generator again.

Every portable generator is designed to handle a specific load (check the manual). Anything over this load will cause the generator to fail. Keep in mind, that some appliances draw more power when starting than they do in operation. These items can be added gradually to avoid overloading the generator.


Clean the Air Filter

Air filters are responsible for ensuring enough oxygen is drawn into the generator. A buildup of dirt and debris will stop clean air entering the combustion chamber of the engine. Because the air filter also prevents damage from this buildup, it’s essential it’s in place. But if it’s dirty, it won’t do its job properly and the ratio of fuel to air will be incorrect.

Never attempt to run the generator without an air filter! If it’s dirty, some air filters can be easily cleaned by following the instructions in the manual. If it’s a paper element filter, it will need to be replaced instead of cleaned.


Generator is Running but not Producing Power

The most common causes of generators failing to start is fuel or oil problems, uncleaned air filters and old spark plugs. But what about if it’s running and not producing power?  This can be a sign of blown fuses or a tripped circuit breaker. The breakers can be reset or replaced by following the manual’s instructions or replace any blown fuses before restarting the generator. Make sure you consider why the fuses have blown to eliminate it happening again.

Portable generators that aren’t producing power may have a damaged motor. This can be checked through a voltmeter and ampmeter. Check with your manual to determine what the right generator readers should be and if your generator is reading the wrong ones, you’ll need the expertise of a professional to repair it.


Learn the ‘Field Flash’


As with cars, the field flash is a simple jump-starting technique that can be used on portable generators that fail to start normally. This shouldn’t be attempted with an inverter generator.

The field flash is useful for starting generators that have been kept in storage for long periods. Start by connecting the generator wires with a battery (negative to negative, positive to positive). The connector cords will be colour coded like the jump start connectors for a car. Next, remove the spark plug and pull the starter cord to get the generator working. The small current from the battery may be enough to get the generator working efficiently again.

Portable generator issues are usually easy to troubleshoot. Before you do anything more than the basics (change engine oil, clean the filter and check/clean the spark plugs), you should seek professional advice.

Need generator parts and accessories such as filters or oil pressure sensors, or considering a new, reliable generator? Speak to our team today.

Posted by: on March 19, 2018, (12:00 AM)


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