Small Engines (Lawn Mowers, etc.)/Honda GX 620 Engine


I have a Thermal Arc welder powered by a Honda GX 620 engine.  It starts easily, but only runs for two to three minutes.  It will restart immediately, but only runs for two to three minutes.  I have changed the fuel filter and hoses, no change.  I have also tried running the engine with the fuel cap loose (heard that there might be a vacuum created in the tank), no change, still runs for two to three minutes.

Interesting...have you replaced the spark plugs?

Does the engine have a low oil sensor?  

Have you checked the carburetor fuel solenoid?

Fuel pump issue?  Copy and paste this all the webpages.

Since it starts right back up it's going to be difficult to narrow the problem down right away.  You will have to verify the fuel pump, solenoid, and I would have a multimeter connected to the regulator to check the power output to make sure the regulator it not malfunctioning causing issues with the fuel solenoid.

Good call on the gas cap...bad gas caps can be very difficult to isolate/troubleshoot.

One other tool that might help troubleshooting is an inline spark tester to verify the ignition modules are not faulty...but I find it hard to believe both would be bad causing the problem.

Are you absolutely sure the fuel hoses and vacuum line on the fuel pump are not leaking?

Small Engines (Lawn Mowers, etc.)

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Eric A. Jones


Lawnmower Repair . Certified Master Service Technician from B&S. Have 23 years experience on B&S, Lawn Chief, Weed Eater, Echo, Peerless, Wheel Horse, Snapper, Atlas, MTD, McCulloch, Homelite and many other numerous brands. Specialize in electrical repair.


Born and raised in the midwest. Started tinkering with engines when I was about 14 on my Suzuki RM-80. I began lawn mower repair at a small hardware store. I knew absolutely nothing. I read lots of repair manuals and met an older fellow who taught me many lessons. I continued working on small engines through high school and paid my way through college working on mowers at the same hardware store. Decided to get away from the midwest and mower repair so I joined the Air Force. I repaired air traffic control electronic equipment and ended up in Hawaii where I got a part time job at Small Engine Clinic. I gained a lot of experience from the Small Engine Clinic and had a blast repairing small engines. I then took the Briggs and Stratton Master Service Technician test and earned my MST. I then traveled to Wisconsin where I attended the factory update training seminar and received formal training. Continued working on mowers part time as I completed 20 years of military. Retired from the military on a Friday and continued in the lawn and garden industry the next Monday.

MAS Aerospace Operations BA Mathematics AAS Electronic Communications AAS Electronic Technology

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