Generac GP3500iO Generator Error Codes & Fixes

The Generac GP3500iO portable generator is able to run nearly any device you connect to it. However, some errors may appear during its operation, including:

Error – Engine Fails to Start

Cause:

The engine will not start if it is out of fuel, the spark plug is disconnected or faulty, or the dial is in the “Off” position. The engine oil may also be low or the wrong type. The engine coil may be faulty and the fuel filter may be blocked with debris. The carburetor may also be flooded, or the throttle plate may be closed.

Solution:

To get the engine running, refill the fuel tank and make sure the spark plug is working. If the spark plug is disconnected, then reconnect it. Replace the fuel filter if it is blocked. Drain the carburetor if it is flooded and open the throttle plate by pushing it fully into the unit. If these solutions do not work, then contact the Generac Customer Support Center.

Error – Engine Shuts Down After Starting

Cause:

The engine will shut down while running if it runs out of fuel, the fuel is contaminated, the oil level is too low or is the wrong type, or the oil level switch is faulty.

Solution:

Refill the fuel tank with the proper fuel mixture. Check the engine oil and fill it to the proper level. If the oil level switch is faulty, consider contacting a Generac Service Center.

Error – The Engine Runs Rough

Cause:

The engine will run rough if the air filter is dirty or clogged, the choke is stuck in the wrong position, or the spark plug is faulty or dirty. The fuel filter may be blocked preventing enough fuel from entering the engine. If the carburetor is gummed up, it could cause the engine to not run smoothly.

The engine may also be cold and need to be warmed up. The spark arrestor could also be clogged. However, under normal conditions, the engine may run not run smoothly and will not require repair.

Solution:

Turn off the choke and make sure the air filter is not clogged. If the spark plug is defective, it will need to be replaced. Drain the carburetor and clean it with a carburetor cleaner and clean the spark arrestor. Adjust the fuel dial and choke until the engine runs smoother.

Error – No AC Output

Cause:

The AC output port may not work if the generator has a short circuit in the port, the connected device has a short, or the inverter assembly is defective. The inverter module may also be overheated. This can also be caused by overloading the generator with devices.

Solution:

Shut down the generator and disconnect all loads. Try restarting the generator with fewer connected devices. If this does not work, reset the generator by pressing the Reset button on the control panel. Check the cords for any frays or breaks and make sure the connected devices are working properly. If the problem continues, contact the Generac Service Center.

Error – Fuel is Leaking From the Unit

Cause:

Fuel can leak from the generator if the carburetor bowl drain is open.

Solution:

Close the carburetor drain bowl by turning the valve clockwise.

The listed solutions should provide fixes to these problems. However, if additional errors arise, consider contacting the Generac Customer Support Center for further assistance.

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Nick Klamecki, Author
About Nick Klamecki, Author

Nick Klamecki is a certified Fire and Workplace Safety expert with 15 years experience in product research and testing. He has a degree from U.C. Davis, is an active outdoorsman and spent years ensuring the safety of special needs children. Nick researches and tests workplace, industrial and safety products and provides advice on their safe use. Learn more about Nick here or connect with him on LinkedIn | Medium