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Weed eater stalls when given throttle

This is a discussion on Weed eater stalls when given throttle within the Small Engines forums, part of the Tech Support Forum category. Many premium 2 cycle engines do not have a vented cap, rather a remote tank vent. A remote vent is


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Old 08-01-2010, 11:40 AM   #21
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Many premium 2 cycle engines do not have a vented cap, rather a remote tank vent. A remote vent is generally more durable and less prone to leakage.

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Old 08-01-2010, 11:45 AM   #22
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Also, I have seen a few of these small engines require something more than the regular/econo grade of gas to run good.

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Old 08-01-2010, 12:48 PM   #23
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Quote:
Originally Posted by Basementgeek View Post
Also, I have seen a few of these small engines require something more than the regular/econo grade of gas to run good.

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Yes. In fact, many mfg's of premium handheld equipment including Echo, Stihl, Dolmar, are now recommending to fuel with an octane rating of no less than 89. Another thing to keep in mind when purchasing higher octane fuel is to put a couple gallons in your vehicle first and then fill your can. This is because the person before you may have purchased regular gasoline, and the lines are still full of that. If you are filling a small gas can you may inadvertently be filling it with the regular gas.
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Old 08-02-2010, 03:25 PM   #24
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Ok, so the dealer called me and said this....

my carb was bad....so its gonna cost $185 total to fix (I already gave them a $65 deposit/non refundable) and the new carb would run about $100....***??? input on this please?
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Old 08-02-2010, 03:50 PM   #25
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How old is it and now much did cost new?

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Old 08-02-2010, 04:19 PM   #26
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its like 10 years old and i'm assuming quit a few hundred dollars, it was to of the line back then and from what ive read, still is top of the line, but no longer manufactured...
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Old 08-02-2010, 04:48 PM   #27
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I guess it will be up to you to decide if it is worth it. I would not pay more than half of what it cost, in todays dollars.

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Old 08-02-2010, 04:53 PM   #28
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The FS85 sold for around $300 10 years ago and was an extremely popular model.
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Old 08-02-2010, 04:58 PM   #29
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any input on their price of a carb? Should it cost $100?? Or could i get a carb elsewhere for much cheaper and slam it on myself? or....should i sell this weedeater as is...and buy a new one?
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Old 08-02-2010, 05:06 PM   #30
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You can find a new carb for $50-60 online...search for Walbro WT-38
Through Stihl...I'm not surprised that it would cost $100. Generally, you figure you don't want to spend on repairs more than half of what the machine costs new, although that does depend a lot on the condition. Obviously you wouldn't want to spend $180 on a machine that has thousands of hours or has been beat up for 10 years.
If you decide to get a new one, you'd want to plan on spending at least $300 to get one similar in quality to the FS85.

EDIT:
You can get the ZAMA C1Q for around the same price...C1Q-S28D.
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Old 08-02-2010, 05:12 PM   #31
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Quote:
Originally Posted by K-B View Post
You can find a new carb for $50-60 online...search for Walbro WT-38
Through Stihl...I'm not surprised that it would cost $100. Generally, you figure you don't want to spend on repairs more than half of what the machine costs new, although that does depend a lot on the condition. Obviously you wouldn't want to spend $180 on a machine that has thousands of hours or has been beat up for 10 years.
If you decide to get a new one, you'd want to plan on spending at least $300 to get one similar in quality to the FS85.
Awesome advice, i think i'm going to search and find a carb myself online and attempt to put it on myself and save about $50-$60 bucks. This weedeater is in very good cosmetic condition, it was very well taken care of, i cant see throwing it away just yet.


EDIT:
whats the difference in carbs? Should we get into that here or should i start a new thread or maybe i should just do some searching :)
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Old 08-04-2010, 01:56 PM   #32
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nate81,

I am a Stihl MST and agree with all of the suggestions here so far and that what you have done is fantastic but I also think you may have overlooked something really simple here.

If your unit bogs out when you give it throttle your low speed circuit isn't getting enough fuel for the mid-range. Since you can't open the jet up as it is fixed the next question is "Did you clean the carb using an ultrasonic cleaner?" This can get the debris out of the circuits that you can't access yourself.

On a side note here, NEVER spray a 2-stroke carb with carb cleaner!!!! They have checkvalves inside that the chemicals will destroy leaving your carb a paper weight. You must use an ultrasonic cleaner and any respectable Stihl dealer will have one that you should be able to borrow for a small fee if not free.

Also, the vent in the fuel cap is often a rubber ring inside of it. If it doesn't breath properly you will have a start and stop issue as the unit can't get fuel.

I'd also like to know what the tech found was wrong with your unit so please update us.

Thanks,

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Old 08-04-2010, 04:51 PM   #33
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Thanks so much for that information TheAlSmith, it is really, really appreciated.

To answer your question about what the tech said, he said this....

my unit needs a new carb due to a 'small peice' missing from the carb....he then proceeded to show me where it was and how small it was....

I was like ..."ok, thanks"...so I am now on a mission to buy a new carb from the internet for around $50 and slap it on and i *hope* this works!! I should have my new carb in about 10 days or so from today so sometime around August 14, 2010.
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Old 08-09-2010, 04:25 PM   #34
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So I got my new carb today, it seems to have fixed my problem :) Now I need to figure out how to adjust it, it is idling wayyyy to fast, the head is spinning. Also i'm noticing a slight delay in the throttle. I can hit the gas, and there is a 1 or 2 second delay.


EDIT: I have all 3 screws turned to the right as tight as they can go...and then turned them back just a little bit. Even with the screws really tight (turned clockwise) it idles really high.
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Old 08-09-2010, 04:58 PM   #35
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Turning them in leans out the mixture (more air, less fuel), which causes the engine to run faster. Try turning them both in until seated (do not force them tight, this can permanently damage both the needles and the carburetor body) and then back them both out 1 1/2 turns. Then turn in the L screw until the RPM's start to drop, the back it off a little bit. If it's still idling too fast, back the idle speed screw out until the head stops spinning. If it bogs when you hit the throttle, back the L screw out a little more (FYI, a little bit goes a long way - even 1/8" turn or less can make a big difference).
For the H screw, if you're not used to tuning a two-cycle engine and don't have a tachometer it can be difficult. To tune it by ear, you turn the screw in (clockwise) until the engine runs smoothly at full throttle, then back it out until there's a slight burble, or four-stroking sound.
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Old 08-09-2010, 06:16 PM   #36
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The screw with the yellow arrow doesn't seem to be adjusting anything at all. I turned it 'out' (counter clock wise) just a bit, and started the motor...and it just wobbled the rest of the way out!
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Old 08-10-2010, 04:14 AM   #37
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That is not an adjustment screw, so tighten that one back up. It looks like that carb probably has a fixed Hi speed screw, so the red arrow would normally be your L screw and the green arrow is your idle speed screw. If the engine bogs when you hit the throttle, turn the L screw out. Once that is set good, adjust the idle speed screw in or out until the engine idles smoothly and the head is not turning.
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Old 08-10-2010, 04:23 AM   #38
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Would it be normal for the idle speed screw to have to be turned out 5-6 or more times? as opposed to 1-2 turns?
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Old 08-10-2010, 04:59 AM   #39
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Yes it is possible for the idle speed screw to be turned out that far. It is tapered and only holds the throttle open to the minimum set amount it is allowed to close. That is how your low idle speed is maintained. Set your low speed screw to the leanest it can be and still give you solid throttle response and THEN adjust the idle screw (green arrow) until the head stops spinning. If you have a tac it should idle at about 2800 RPM but if not I'm sure you can tell by ear from experience how it should idle smoothly yet still not have the head spin. If you can't get the head to stop spinning then you have an issue with your clutch (weak or broken springs).

Anyways, I hope this helps.

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Old 08-13-2010, 03:09 PM   #40
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Ok, i found out why it was idling soooo fast....when i put the throttle cable back on, there is another adjustment ...i had it way too high, which pulled on the throttle lever = idle high. soooo after i fixed that...i played with the 2 screws and i got it to idle very, very nicely, the head will not spin any longer. I still hear a 'pinging' noise and notice a slight delay and hesitance going from idle to full throttle. I think this may be a gasoline issue. I am going to dump all of my gas, and get some fresh 97 octane (after putting about 2 gallons into my car i will then put 1 full fresh gallon of pure 97 octane in my mix jug for my weedeater)

Another quick question....whilst weed eating, do i hold the throttle wide open?? It just seems like wayyyy to much power for the little weeds and trimming i need to do. Can't I just realtime adjust my speed (up and down constantly) and get the same effect?


To all whom have helped...you saved me soooo much money and I have learned a lifelong lesson that I can teach my Son one day, so thank you!

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