weedeater 128cd runs good then rough, good then rough

ssnead

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  • / weedeater 128cd runs good then rough, good then rough
Have a weedeater that will run good for a minute then run rough no pwer then good again. Changed fuel, fuel line, carb, spark plug. still runs rough any ideas? not much else to change. yes i adjusted the screws hi-lo
 

Bertrrr

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  • / weedeater 128cd runs good then rough, good then rough
This is a tough one but if there's a carburator adjustment have someone hold it down full throttle while you play with the adjustment screw until it levels off, these 2 cycle machines can be finicky
 

bertsmobile1

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  • / weedeater 128cd runs good then rough, good then rough
You start by finding out what the problem is , then repair it .

The first thing you check on these engines is the fuel tank & vent
Once I became aware of this I changed more fuel caps than I did carbs
Look up "Joe Pace- two stroke diagnostics " he has a series of 3 you tube videos where he runs through the start of the Husqvarna Tech training manual.
A real eye opener for this little black duck.
Secondly if you bought that carb as part of a cheap kit on line then there is a 75% chance the carb is a defective factory reject , the yellow fuel line is cellulose plastic & will crumble a year after it sees petrol & the fuel filter has a leak so sucks unfiltered fuel .
 

ssnead

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  • / weedeater 128cd runs good then rough, good then rough
Will check that vent. Looked for the joe pace videos but could not find any from him. I found that the replacement carbs were cheaper than the parts to rebuild one. the cheap ones seem to work, i bought 5 used 3 and still working. Was looking for a site with just the parts that would be cost effective. while i am not an expert, i have not run into a problem like this before. the fact that it will run fine for a couple of minutes then rough, well logic does not apply to this problem, maybe the coil...
 

Bertrrr

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  • / weedeater 128cd runs good then rough, good then rough
I could be the coil but I've yet to run across a bad coil, I did have to drill a vent hole on a small Honda machine that was acting like this, so that may be a good idea to eliminate the venting issue. Don't rely on a new plug , I've had to change plugs a couple times on these small guys even after installing a new one.
 

sgkent

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  • / weedeater 128cd runs good then rough, good then rough
depends on how long it runs good then bad. When adjusting the screws, they have a considerable lag because it takes time for the fuel mixture in the crankcase to clear out to the new mixture. Also look in the tank to be sure the filter hasn't fallen off. I had a hedger doing that and it was because the fuel filter had fallen off and the line was flopping around going in and out of the fuel in the tank.
 

DaveTN

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  • / weedeater 128cd runs good then rough, good then rough
Why not boil it out and clean it good then blow it out with compressed air and try again?
 

ssnead

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  • / weedeater 128cd runs good then rough, good then rough
I have ordered anther carb, while i do not think this is the issue nothing left to try. I did make sure the cap vent was working.
 

bertsmobile1

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  • / weedeater 128cd runs good then rough, good then rough
Sit down with a long cool drink and watch all 3
In particular the last one listed
The entire fuel system is a closed loop pressurised system
any pressure leak will give you grief

And I know when you search Joe Pace you get 15 pages with links to Joe pace the musician but the 2 stroke ones are not hard to find if you look further than the first page on google .
 
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