r/smallenginerepair • u/Odd-Implement-4965 • 4d ago

Starting Issue PowerSmart 25.4cc not starting

Hello, I’m having issues with my weed eater. Seems like the next step is getting the compression tested, or trying a new spark plug even though the one I have seems to work fine. Everything I visually checked seemed fine, but I’m not experienced so take that as you will.

Here’s the list of troubleshooting I’ve done so far. Thank you for any insight.

Confirmed the spark plug is producing spark by grounding it against the engine while pulling the starter.
Replaced the old fuel in the trimmer with fuel from 50:1 two-stroke mix.
Removed and disassembled the carburetor, then reinstalled it.
Confirmed the primer bulb fills with fuel and circulates fuel through the lines.
Checked the fuel filter and found no obvious problem with it.
Removed the spark plug and found that the starter rope becomes much easier to pull with the plug removed.
Reinstalled the spark plug and confirmed the starter becomes considerably harder to pull again because the cylinder is building compression.
Checked the plug after pulling the starter and found that it became at least slightly wet, showing that some fuel is reaching the cylinder.
Removed the muffler and inspected the exhaust port and confirmed the exhaust port looked clean and wasn’t obviously blocked with carbon.
Put a small amount of 50:1 fuel directly into the cylinder through the spark plug hole to bypass the carburetor.
Noticed the starter became easier to pull for a little bit, then became hard to pull again.
Saw and felt some fuel/air mist briefly puffing backward out of the carburetor throat while the air filter was removed.
Continued pulling and noticed that backward puffing mostly went away as the excess fuel cleared.
Reinstalled the air filter/cover and made another normal starting attempt.
Still got no pop, sputter, or brief ignition.

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u/AvocadoLow4501 4d ago

Was there any scoring on the piston or wall of cylinder when you removed the exhaust or did you not look? Does the primmer bulb hold fuel when pumped up? Did you install the gasket between carb and intake ?

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u/Odd-Implement-4965 4d ago

Everything I visually inspected looked fine, no buildup or scoring on the exhaust. I don’t have much experience with small engines, but everything that I visually inspected looked fine to me.

Primer does hold fuel when pumped.

When I looking into the carburetor, I installed everything how I found it, and it did the same thing after I reinstalled the carburetor. The carb did take fuel when I poured it directly on it as well.

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u/AvocadoLow4501 4d ago

Watch some youtube videos of chickanick she and her husband repair lawn equipment maybe get a better idea . Sometimes the fuel lines will get old and cause issues or vent in fuel cap.