What Causes Generator Overcrank [5 Reasons with Fixes]

Generator over cranking is a common problem that many generator owners and operators face. 

This happens when the engine tries to start but fails, and the starting system keeps cranking in an attempt to start the engine. In simple terms, the generator continues to crank but it won’t start, hence the term ‘overcrank’. 

There are several reasons why this might occur, ranging from simple issues like a low fuel level or battery power to more complex problems such as mechanical failures within the generator itself. 

This article will delve into the various causes of generator overcranking and offer solutions to address and prevent these issues.

What Causes Generator Overcrank

What cause generator to overcrank

1 . Low Fuel Level

One of the most common causes of a generator over-cranking is a low fuel level. The generator requires a certain amount of fuel to ignite and start the engine. 

Without sufficient fuel, the engine will crank but not start, leading to an over crank condition.


To resolve this, regularly check the fuel levels in your generator. If the fuel level is low, refuel the generator before attempting to start it.

 Implementing a routine maintenance schedule to monitor fuel levels can help prevent this issue from occurring.

2 . Insufficient Battery Power

Another typical cause for generator overcranking is insufficient battery power. The battery is responsible for providing the initial power to start the generator’s engine.

 If the battery doesn’t have adequate charge, it may not provide the necessary power to start the engine, leading to an overcranking situation.


The solution to this issue is two-fold. First, ensure that your generator’s battery is fully charged before trying to start it. 

Second, perform regular battery maintenance which includes checking battery connections for any corrosion and ensuring they are clean and tight.

If the battery is old or unable to hold a charge, it may be time to replace the battery.

3 . Faulty Spark Plug

A faulty spark plug is another major cause of generator overcranking. The spark plug plays an integral role in the ignition of the generator’s fuel-air mixture.

 If it becomes dirty, worn out, or damaged, it can impede the spark necessary for ignition, leading to an overcrank condition.


To combat this, the spark plug should be inspected and cleaned periodically. If it’s excessively worn or damaged, replacement is necessary

Regular maintenance and timely spark plug replacement can prevent overcranking and improve the overall performance of your generator. 

4 . Blocked Fuel Line

A blocked fuel line is another common cause of generator overcranking. The fuel line ensures a steady flow of fuel to the engine.

 If the line becomes blocked or clogged due to debris or sediment, it can prevent the proper flow of fuel, resulting in an overcrank condition.


The solution to a blocked fuel line is to periodically inspect and clean your generator’s fuel line. This can be done during routine maintenance checks.

 If a blockage is found, it should be cleared out immediately.

 In severe cases, if the fuel line is damaged or excessively blocked, replacement might be necessary

5 . Mechanical Failure in the Generator

Mechanical failures in the generator can occur due to various reasons, including worn-out parts, improper maintenance, or even manufacturing defects.

 When these failures happen, they can impede the generator’s ability to start, resulting in an overcrank.

 The starter motor, the alternator, or the generator’s control board are often the components that succumb to mechanical failures.


The solution to a mechanical failure generally requires professional intervention.

 If you suspect a mechanical issue, seek the help of a qualified technician who can accurately diagnose and repair the problem. 

Regular preventive maintenance is critical in avoiding mechanical failures.


In conclusion, generator overcranking is a prevalent issue that can result from a variety of causes, including low fuel levels, insufficient battery power, faulty spark plugs, blocked fuel lines, and mechanical failures within the generator.

Regular maintenance and vigilance can help prevent most of these problems, thereby ensuring that your generator operates efficiently and reliably when you need it most.


What is generator overcranking?

Overcranking happens when a generator keeps trying to start without success, often due to issues like low fuel, insufficient battery power, or mechanical problems.

How can I prevent my generator from overcranking?

Regular maintenance, including checking fuel levels, ensuring the battery is fully charged, and inspecting the spark plug and fuel line, can help prevent overcranking.

What do I do if my generator’s fuel line is blocked?

If your generator’s fuel line is blocked, you should inspect and clean it during your routine maintenance checks. If the blockage persists, consider replacing the fuel line.

What should I do if I suspect a mechanical failure in my generator?

In case of a suspected mechanical failure, it is recommended to seek help from a qualified technician who can accurately diagnose and repair the problem.

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