Trimmer Runs When Fully Choked

I have a Homelite string trimmer, with a Zama C1U carb. It starts easily, and runs (fast) so long as it is in full choke. But, it dies as soon as the choke is released. I have taken the carb completely apart and cleaned the obvious places. Suggestions? Is there some not-so-obvious something I am missing?

My friend has a Roybi trimmer with the same carb, and it behaves the same way.

Ready to try anything,
Thanks,

 

Most cases when a small engine like that runs ok on full choke it is running lean. You could adjust the needles, but I suggest doing a through cleaning and installing new gaskets and diaphragm. Rebuild kits are less that $10

 

Tolyn Ironhand pretty much covered what I would suggest. The only thing left to suggest is checking your fuel lines to see if there is a clog somewhere.

When you took it totally appart, did you put the needles back in exactly as they where?

 

I never took the needles out. This is one of the carbs where that is not so easy. I was hesitant to try it. There is a plastic cover which must be destroyed to remove the needles. I wanted to try and remove them. Could I do so and get them back?

 

Try adjusting the needle.
Tighten it (just until it'll stop turning with very light pressure), then back it out 1.5 turns (I think it is). Give that a try and see if that helps. You will more then likely have to play with the needle a bit to get it running 100%.

 

Pop the limiter cap off of the screw closest to the air filter. That is the high speed mixture screw. Back the screw out 1/8th turn and see if it runs better.

 

OK, I am slow but I finally have something to report.

I cleaned the carb and installed a rebuild kit. That helped, but the trimmer still sputtered and died after idling for several seconds.

I removed the limiter caps, removed the needles, cleaned with carb cleaner, and reinstalled the needles. The trimmer is now running properly.

There is too much smoke, but at least some of that may be due to cleaning fluids left everywhere. During this process, I cleaned the exhaust screen, spark plug, cooling fins, everything I could find. But, if it continues, which needle should be adjusted first?

Thanks to everyone,

 

I forgot to mention one thing. When installing the rebuild kit, I did not replace the welch plug. What symptoms might I expect if that does need to be replaced?

Thanks again,

 

Too much smoke is from too much oil in the gas, or the engine is getting too much gas. If the engine is running right but smoking too much, it's from too much oil. Generally if it's too much gas causing the smoke, turning the high speed screw clockwise some will help. It's the mixture screw that is closest to the air filter.