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Small Engines (Lawn Mowers, etc.)/Honda GX270 9hp engine wont start


QUESTION: Good day,
I recently purchased a used generator that has a 9hp Honda GX270 engine. The engine was seized when I purchased it, so I drained the old oil and sprayed penetrating oil into the spark plug hole and repeated until the engine unseized about a week later.
I also cleaned the carb, drained the old gas, replaced the oil as well as the spark plug. After all this the engine would not start, so, I replaced the carburetor with a new one as well as replaced the fuel line. The engine seems to have good compression, but the only way the engine will run is if I spray starting fluid into the air cleaner opening.
What else could be the problem?
Everything I've read suggests the carb, but it's brand new.
Any help would be greatly appreciated.
Thank you.

ANSWER: I'd have to agree...sounds like the carb is not delivering fuel.  However, I have seen sticky intake valves cause this problem on Honda engines.

Have you removed the valve cover and observed the intake valve in operation or at least inspect the valve to make sure it is opening and closing all the way?  

---------- FOLLOW-UP ----------

QUESTION: I'm by no means a mechanic, although, I follow instructions very well.
How would I go about checking the intake valve? I know its the valve closest to the carb, but I'm not sure how to check if it's functioning properly.
Thank you for your help

The best method is to use a leak-down tester to see if the intake valve is sealing.  These are pretty pricy for home use...don't think Autozone rents them either.

What you can do, and this is how I've found most sticky intake issues on Honda engines is just remove the valve cover the cover above the spark plug, usually 2 to 4 bolts/screws, and then pull the string and see if the valve opens and closes properly.  Opening is usually not the issue.  Most of the time they are slow to close because there is sticky gum deposits in the valve guide.  The valve should close just as fast as it opens.

Remove the spark plug before pulling the's much easier to see if the valve is slow closing.  

Let me know what you find.

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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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