Gas Weed Wacker with Engine Trouble

[l008com]

I have an otherwise pretty nice Husqvarna 2 cycle gas weed wacker. AKA Trimmer. It's about 5 years old. It has two problems, which I'm sure are the same problem. And it's had them since it was new. Rather than fighting with this thing every week, I really should just fix it.

Symptom 1:
It dies if you let it idle. It will run with the choke partially on but with the choke fully off, it will slow down and usually in a few seconds to a minute, it conks out. It seems to die faster when it's fully warmed up, than when it's cold.

Symptom 2:
If it is idling or close to it, and you pull the trigger to rev it up to operating RPM, it will bog down and potentially stall out if you pull the trigger too fast. If you raise the RPM slowly, it gets up to speed and then it can handle the higher RPMs just fine.

I do NOT think my problem is that I need an idle screw adjustment. I think my problem is that the air/fuel mix is off. But I'm not sure if that can be adjusted, or how it can be adjusted. It's been doing this since it was brand new, and it still otherwise runs like it's new. So I don't think it's being caused by any other typical "old engine" problems.

But I'm no mechanic so maybe I'm totally wrong.
Also note, I've always run it with 1 ounce of seafoam in the gallon of oil gas mix. So I would expect the insides of the engine to be very clean.

So what do you think?

 

[bertsmobile1]

It is rich on the idle jet
A lot of hand helds are supplied like that and need to be retuned when run in .

 

[sgkent]

most of those two cycle carbs have a life span of just a couple years. Learn how to rebuild it or replace it. The diaphragms in it that control fuel delivery stretch and go bad. I have found that draining the tank and running the device dry after each use doubles the life but even so the carbs go bad with the symptoms you describe.

 

[l008com]

But this isn't a new problem its had since it got old. It's been like this since day one.

 

[Tiger Small Engine]

But this isn't a new problem its had since it got old. It's been like this since day one.

My question is why have you put up with this for five years? Sounds like a simple carburetor adjustment. OEM carburetors will last for several years. I still have the original in my Stihl FS250R and have only replaced the metering diaphragm once.

 

[slomo]

On a 5 YO trimmer, just get a carb rebuild kit or new OEM carb. The diaphram is probably "hard as a carp". Taryl

 

[StarTech]

Boy a lot of techs with no idea of what is wrong. The closest is Slomo and Tiger a close second.

It not tuned rich but is on the lean side; hence, the reason it runs better with a little choke. And as the rubber metering diaphragm ages it does stiffen up over time and I have seem rock hard on non runners. The Mylar fuel pump diaphragms do deform some over time but the rubber diaphragm can not stretch as it is rubber coated cloth.

One thing I do see in new carburetors is that the metering lever is usually set too low which cause the carburetor run lean at full speed as the needle valve can not fully open. And this can idle problems too. On these carbs even a slightly stiffen metering diaphragm can cause problems.

Now the problem is it does take a knowledgeable technician to diagnose and repair these two cycle engines. You must have the proper tools like the mixture adjust tool and and most cases the correct metering lever setting gauge tool. Zama usually the easiest to set as nearly all are set the same but with Walbro there is multiple settings depending the carburetor model which is I got the Zama Z tool and both of the Walbro W tools. For home owner these are expensive for one time use. It also doesn't hurt to have a pressure/vac tester to test the sealing of the carburetor and metering needle sealing plus tach to set the idle and max rpms. Again a shop can justify these as they are repeated used.

And many of these carbs have to be tune slightly rich on idle mixture so you can have a quick acceleration when you pull the throttle lever quickly. IE very little lag getting up off idle speed.

One thing of note if you tune to carb too lean you run the risk of destroying the PNC from lack proper oiling and overheating. Personally I would advise the OP let a professional two cycle tech do the work. I just had to give a customer the bad news that his expensive Stihl is burn up because he let his cousin work on it and he had left the carburetor loose. Costs more now to repair than a new saw but does make a good Stihl boat anchor.

PNC > Piston and Cylinder

One thing of note here is that companies are getting to where they will not sale you a carburetor repair kit but only sale replacement carburetors. More money in their pockets. Stihl is a prime example of these companies. And with Stihl owning Zama many of the repair kit and parts are no longer available so you have to buy replacement carbs. Can't even look up the parts so I can get parts out my stock parts any more. And Walbro site no longer have full carb IPLs as they have gone to kits and carbs only.

 

[sgkent]

I get my kits here: https://www.carbtech21.com/default.asp

 

[l008com]

My question is why have you put up with this for five years?

It's very easy to work around this problem, it's more of an annoyance than a problem. But 5 years is my limit I agree that it sounds like some kind of fuel adjustment issue but beyond that, I don't know how to fix it so I just ignored it.

 

[l008com]

Personally I would advise the OP let a professional two cycle tech do the work.

LOL Walk into an engine shop with a 2-cycle anything and see what happens. Here's a hint, "we don't work on those, throw it away and buy a new one" is what you get. Others say right on their website "NO LONGER SERVICE BLOWERS OR STRING TRIMMERS". I've never found any shop anywhere near me that will work on 2 cycle engines. I had two different very problematic chainsaws over the years and after searching high and low, I gave up.

But this trimmer is a different situation. Its a good brand and a good machine that, aside from this problem, runs great and always has. It's certainly worth fixing. Especially if it's just a matter of taking off the air box and adjusting a screw. I don't think the problem is that the carb itself has gone bad. And I base that on the fact that it's had the exact same problem since it was brand new, and it's never gotten any worse.