Why will my weedwacker only run on full out with the choke open?

This is about penile disfunction surely

Your topic question mentions the choke, but that’s not discussed in your details. I’m not going to assume that you know the difference between choke and throttle, so the following may be too elementary to help answer your question. However, it seems to be a sort of confused question, so… maybe not.

The choke is a mechanical device that limits the amount of air entering the combustion chamber. This is normally closed (added air shut off) temporarily for a cold start. In other words, to promote ignition and start the engine at a cold start the mixture is intentionally fuel-rich and starved for air. As the engine warms the choke is opened (either manually or on many engines these days, automatically) to lean the mixture and burn the fuel more efficiently.

The throttle, on the other hand, which is normally controlled manually (“the gas pedal” on a car and presumably the trigger on your hand-held weed-whacker) feeds fuel to the engine.

For many hand-started gasoline engines of this type, the manual choke being closed in preparation for start may also feed additional fuel to the carburetor / ignition chamber, or you may be prompted to pump a bladder or other device to manually prime the chamber with fuel for the starter to engage. As the engine starts, then, there is an intentional surfeit of fuel to burn off, and even without engaging the throttle the machine will run fast as that fuel is consumed. The choke being shut may also cause the fuel to feed abnormally fast (faster than a normal idle, that is) in order to promote the engine warm-up and consequent opening of the choke to enable normal idle speed. (In other words, the “startup fast idle”.)

As for why the engine fails to maintain a normal idle once started and warmed up, that’s a question for a better mechanic than me. Have you checked the air filter? Those can get clogged with the dust and debris that is normally stirred up with this process operation, and too-little air to a warmed-up gasoline engine will tend to stall it out. And people aren’t well attuned to checking air filters.

I’ll ask hubs. We used to own a small engine repair shop. Before I do, have you tried cleaning the carburetor and the jets in the carb?

Also, have you tried replacing the fuel line? What have you tried?

Hubs said: Could be spark plug. Could need a carb kit (always a good idea, whether or no) but he’s betting that the exhaust screen is plugged.

It sounds like it’s running too rich. Lean it out. (Have a qualified small engine tech look at it.)

(Well, a qualified small engine tech just did, actually. He just couldn’t put his hands on it himself. He gave @rojo the benefit of his years of experience with all engines, including small engines.) Yeah, take it to a tech, but a Poulan isn’t exactly a high end trimmer. You want to be careful not to spend more on diagnostics than it would take to buy a new one.

Throwing parts at it is OK too, IMO. All of the parts you throw at it are going to be needed sooner or later.

So, let us know what you find @rojo.

Threw the gas in the can away, mixed up a new batch with oil at the 50:1 ratio, works fine now.

Gas was only a couple of months old. I mixed it up at the start of summer.

@kritiper when you say lean it out, what exactly do you mean?

He means put less 2 cycle oil in the gas.

Glad you got it running.

Actually he means to change the air/fuel ratio at the carb. Lean means more air and less gas.
Weed eaters are persnikety beasts. I’m good with engines, can rebuild motorcycle carbs by memory but my trimmers are electric.

@ARE_you_kidding_me You are correct when I said to lean it out. Maybe there is a air jet that’s plugged. Or the air filter is dirty. I had a gas unit I bought from my dad and I spent more time trying to get it to run that actually using it. So I gave it away and got an electric.

Thanks everyone for the input.