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Hey folks,

Kind of stumped here. I have a Troybilt TB110 from 2011 (model: 11A-A26M011) with a Briggs and Stratton 126T02-0675-B2 engine. It starts up briefly and then stops. Here's what I've done so far:

• Replaced the air filter
• Replaced the carburetor
• Replaced the ignition coil
• Drained fuel tank and replaced with fresh fuel
• Cleaned fuel tank cap
• Changed engine oil
• Replaced spark plug

My googling hasn't helped me identify some less common causes of my lawnmower's problem(s). What might else it be? Maybe something further downstream from the carburetor? Thanks in advance for help troubleshooting.

More questions than answers. OEM or knockoff carb? Primer, choke or auto-choke carb? Set the air gap on coil to .010”? Does it restart after it shuts down? With these answers we can give you ideas on how to proceed.

Assuming Auto Choke-Tstat-Air Vane model. Pull the air filter and look at choke plate. It should be closed when engine is cold. If not: tstat, air vane or spring problem. If you have a primer bulb, push it a few times, start engine, have a helper push bulb every second or 2. See if it keeps running. It may warm enough to stay running with an open choke.

Sounds to me like you have a blockage in the fuel line.

Rivets said:

More questions than answers. OEM or knockoff carb? Primer, choke or auto-choke carb? Set the air gap on coil to .010”? Does it restart after it shuts down? With these answers we can give you ideas on how to proceed.

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OEM carb. How can I tell the difference between choke or auto-choke? Yes, air gap set to .010". It does restart after it shuts down, but it takes several more pulls. Thank you!

dougand3 said:

Assuming Auto Choke-Tstat-Air Vane model. Pull the air filter and look at choke plate. It should be closed when engine is cold. If not: tstat, air vane or spring problem. If you have a primer bulb, push it a few times, start engine, have a helper push bulb every second or 2. See if it keeps running. It may warm enough to stay running with an open choke.

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Thank you, I will inspect the choke plate and report back. I can identify the air vane and spring, but am not sure what a tstat is.

cpurvis said:

Sounds to me like you have a blockage in the fuel line.

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I had thought the same thing (and it may still be true) but the bowl under the carb reliably fills and the fuel line itself does not appear to be obstructed. Could I be missing something else? Thank you.

The thermostat is on the muffler.
Look up "How Briggs auto choke works" on YouTube and look for a video by Taryl Fixes All.

Nicapyke said:

I had thought the same thing (and it may still be true) but the bowl under the carb reliably fills and the fuel line itself does not appear to be obstructed. Could I be missing something else? Thank you.

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How are you checking that the carb reliably fills?

Scrubcadet10 said:

The thermostat is on the muffler.
Look up "How Briggs auto choke works" on YouTube and look for a video by Taryl Fixes All.

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I rest my case!......lol

Alrighty folks, watched that educational (and hilarious) video by Taryl and checked my thermostat, air vane, and spring. All working correctly, and choke plate is closed when cold. And there is no obstruction in the fuel line and fuel is getting to the carb because when I disconnect the bowl from the carb, it is full. Still no dice. What's next?

You need to see if runs normally for 5-10 secs. Try spraying fuel into carb throat after a helper pulls cord. A shot every 1-2 secs to keep it going. If it runs normally, you still have a fuel delivery problem. fuel may be in bowl but it's not traveling thru main jet to the combustion chamber.
Do you have a primer bulb? You can keep pushing it to test engine run.
If your "run" is more of a burp - you may have a sheared flywheel key = out of timing.

From everything you posted I’m thinking you need to look at the original carb. First take a look at the float on the old carb. When you tip the carb upside down does the float stay level with the carb body or does it go up from the pin side to other side? If it is not level the float seat has swelled and the engine will run lean and be hard starting. Then check the new carb for same results. You may have gotten a bad carb.

dougand3 said:

You need to see if runs normally for 5-10 secs. Try spraying fuel into carb throat after a helper pulls cord. A shot every 1-2 secs to keep it going. If it runs normally, you still have a fuel delivery problem. fuel may be in bowl but it's not traveling thru main jet to the combustion chamber.
Do you have a primer bulb? You can keep pushing it to test engine run.
If your "run" is more of a burp - you may have a sheared flywheel key = out of timing.

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Definitely more of a burp. Thanks for the suggestion. I'll inspect the flywheel key.

Rivets said:

From everything you posted I’m thinking you need to look at the original carb. First take a look at the float on the old carb. When you tip the carb upside down does the float stay level with the carb body or does it go up from the pin side to other side? If it is not level the float seat has swelled and the engine will run lean and be hard starting. Then check the new carb for same results. You may have gotten a bad carb.

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Thanks, will check this out.

Well folks, I appreciate all the help. Engine is running just fine again. Turns out this problem may not have even been related to some of the things I was saying. I tried all the suggestions, but when none worked, I ended up just looking at a diagram of the engine and starting to take things apart and clean them. Took the cylinder cover off the front and went to town with a brush around the piston and the valves. Also liberally sprayed Seafoam in places that I could not get at with the brush but I reasonably believed to lead to parts of the intake or combustion chamber. Manually rotated the flywheel, watched the cycle of the piston and the valves opening and closing, and cleaned as much of the surface area as was made available by the movement in the cycle. Turns out one of the valves was sticking a bit. Got it to operate smoothly, put everything back together, and bingo.

Again, thanks for y'alls insight.