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Discussion Starter #1
Hi, I bought a used Craftsman trimmer for cheap, unkown age, but pretty new as it has Incredipull feature. Sears Model# 316.791890, MTD model # 41ad770c799. I'd like to know what carb adjustments can be made on it? Basically it starts ok, but once you try to rev it up, it pretty much stalls most of the time, and it also won't idle down most of the time either, like the "fast idle" is not letting go. It acts like its bogging down whenever I try to rev it up. Anyone here who can help?
 

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Most likely the carb low and high end needles need to be opened up 1/8 to 1/4 turn each. You need a special tool to adjust the carb. That unit should still be under warranty (look at the serial number, the first 2 numbers tells you the year of manufacture) so you can send it in and have it adjusted at no cost.
 

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hankster said:
Most likely the carb low and high end needles need to be opened up 1/8 to 1/4 turn each. You need a special tool to adjust the carb. That unit should still be under warranty (look at the serial number, the first 2 numbers tells you the year of manufacture) so you can send it in and have it adjusted at no cost.
Warranty only applies to the original purchaser with the original proof of purchase. And most often, carburetor "maintenance" (which is what the OEMs call it) are not considered a product defect and therefore not warranty items.
 

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Discussion Starter #5
I forgot to add that the carb has automatic choke. You only have to prime and pull the rope to start it. I suppose I can try to see if Sears will repair this at no cost, but I doubt it since I bought it used but I've never dealt with them before on repairs-I can only hope they'd repair it for me at no or minimal cost...a replacement carb is $44 from Sears and $40 at other online places Maybe I should just replace it if I find out that Sears won't repair it at no cost? Also, if it just needs adjusting, why can't I just buy the tool(s) needed to do it?
 

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It depends on the carb. Those trimmers can use any of 3 different carb adjustment needles. The splinded, D shaped or butterfly headed needles. Generally carb adjustment tools are not available to the public.... it is an EPA mandate.

A new carb may or may not help. The adjustments on these models with the auto choke are pretty sensitive. Hint: If the first 2 numbers serial shows 05 or higher just take it into Sears to get it repaired. Tell them you got it as a gift so you have no paperwork for it. Let them know that the serial number shows it is less then 2 years old and it's in the warranty period. Since it is within the 2 year warranty period there should be no charge to get it fixed.

If they want to charge you, the cost would be $52.99 for the carb adjust. That is the minimum labor fee. You didn't say where you are located so I don't know what repair center would repair it.
 

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Discussion Starter #8
Thanks for that reply, are you sure it has a 2 year warranty? The serial # on this unit is: 11046dc1162. Does that give the date of when it was manufactured?
I guess I'm probably gonna be screwed if the carb is not adjustable. I called a couple of Sears stores and they kept saying they need a phone number or an address in order cover any warranty repairs :( . If it was a gift then I'd be able to tell them the name of the giver, right? :cool: The nearest to me service centers that I can find are in Des Moines, Iowa (110 mi) the other in Moline, IL (80 mi)?
 

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That can't be the serial number... it should start with a 0 (zero) as in 05 or 06. That model was only produced in the last year or so, so it has to still be under warranty. The model/serial tag is on bottom of the black housing just in front of the spark plug on a white tag. You don't have to take it to a service center, you drop it off at any store and they ship it for you. Give them any phone number you want and when it doesn't show up on their computer just tell them guess their computer system is screwed up. Just depends on how much you want to bluff them. ;)

Why am I saying this? Because that unit is still less then 2 years old and is still under warranty. The problem you have is not all that uncommon (not that it a huge problem but we do see them now and again) and personally, since it isn't an uncommon problem, it should be taken care of. If you drop it off and they want to collect some $$$$, don't give it to them. They will accept the unit for repair anyways and when the service center calls with an estimate, tell them to look at the serial number and it is less then 2 years old and should be covered.

As a repair tech., they should also check the paperwork when they go to fix it. If the serial shows it to be within warranty, they should normally cover it no matter if the paperwork is marked warranty or not. A couple notes on the paperwork and there is no charge. Additionally, this is the perfect time to send it in as the work load is very low and that means they are more then happy to get any work this time of year.

Most likely your repair center is just outside Chicago. Anyways, it's up to you... I personally would cover it but then that isn't a company "policy" and I'll do a little more for the customer then is required.
 

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Discussion Starter #10 (Edited)
Well I removed the rear engine cover and saw that this engine has the D shaped mixture screw "doohickies" on the carb. Are they part of the screw or just plugs that allow access? They appear to have o-rings beneath them, are they seals? They don't turn at all, even with some force, of course I don't have the right tool to turn them. I only tried turning them counterclockwise.
I'm going to guess that the serial # I listed above may start with 04 instead of 11? The label is confusing to read, but the numbers following the "S/N" portion of it does read exactly as this: S/N (S) 11046dc1162. Then there's a bar code directly underneath these numbers.
I can get it to start everytime eventually, but it's a bit tricky when it's cold. And after starting it won't kick down off fast idle, even though the throttle lever's linkage is off the fast idle cam. But it will SOMETIMES idle down to a more normal speed, but MOST of the time it will not slow idle. If I push the throttle to rev up the engine, it slows down then starts picking up speed (if it doesn't die) slowly before reaching top speed. Sound like a mixture screw problem or a faulty carb? The fast idling issue has me scratching my head...related to the slow revving/stalling problem? BTW I pushed in the primer bulb while trying to rev it and it immediately bogs down and even stalled a couple of times when I tried this. So, it's already running too rich or does priming it while it's running always cause a too rich condition, lol? Or is the primer line full of air after the engine is already running?
 

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hankster said:
That can't be the serial number... it should start with a 0 (zero) as in 05 or 06. That model was only produced in the last year or so, so it has to still be under warranty. The model/serial tag is on bottom of the black housing just in front of the spark plug on a white tag.
Actually "hankster" if you look back at the original post, that trimmer was made by MTD for Sears, in this case that WOULD be the MTD format serial number. In a current MTD serial number, the 5th number is the Year of manufacturer, which in your case would be 2006. :thumbsup:
 

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newz - Doh... was thinking a straight Sears number and not the MTD number so you are correct.

Fortune - Those D shaped things you saw are the mixture needles. That tool you pointed out earlier will fit those screws if you want to go that way. Yes, pushing the primer will stall the engine. Trust me, the carb is NOT bad, it just needs a slight adjustment, we see it daily (but then we also fix 100+ units a day).
 

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Discussion Starter #13
hankster said:
newz - Doh... was thinking a straight Sears number and not the MTD number so you are correct.

Fortune - Those D shaped things you saw are the mixture needles. That tool you pointed out earlier will fit those screws if you want to go that way. Yes, pushing the primer will stall the engine. Trust me, the carb is NOT bad, it just needs a slight adjustment, we see it daily (but then we also fix 100+ units a day).
So why do they not turn easily? I shoved a wire butt connector over them, but couldn't get them to budge...what keeps them from turning if they're screws & not plugs?
 

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Discussion Starter #14
Well the service center at Sears has accepted the trimmer for in-warranty repair, although they'd only set the date of purchase based upon when that trimmer model was manufactured at it's earliest date of release (March of '06). Either way, it'll get looked at w/o charge to me, wish me luck on them fixing it properly, lol.
 

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Discussion Starter #16
Well I picked up the trimmer yesterday and started it. I primed it 10 times and then it took 6 pulls to get it started. After revving it up it does idle down, although slowly. It also is pretty cold blooded, it'll stall if I don't give it about 2 minutes to warm up. It will still bog down & stall if I have the powerhead turned on its left side facing down, although this does make the fuel feed line go to the top of the tank, lol. Also, it revs up like this when I give it full throttle off idle: the powerhead shakes pretty hard off idle then revs up in a slowish manner, nothing like what I'm used to with 2 cycles, do you think there's still a problem? It's even slower to rev up with the brushcutter attachment, although it is heavier to spin the blade vs. the trimmer head. It doesn't smoke except I did notice a bit of blackish puffing when gassing it off idle when it was cold. I used 40:1 fuel (87 octane) to oil. The Sears service center in Melrose Park, IL just adjusted the carb and "fixed" the fuel cap. I can't test it out under load as all I have to work with is snow, lol. It is cold out (27*), do you think this would make it run like it's too lean yet? What do you think?
 

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Fortune50 said:
It is cold out (27*), do you think this would make it run like it's too lean yet? What do you think?
Anything's possible. Everything with consumer 2 cycle stuff always goes back to the "you get what you pay for" saying.
 

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Those are really cold blooded engines. 2 minute warm up wouldn't be out of line on a warm day. Those models use a flex shaft and with the heavy trim head it can cause some shaking when reved if it isn't running smooth (can those engines even run smooth?). My guess is it just too cold to get the engine warmed up really well unless you'd run it for 10 minutes or so.
 

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Discussion Starter #19
I thought I'd update this thread. The trimmer started and ran ok in the warm weather, although it doesn't like to be tilted on its side (don't remmber which side) or it'll die. After I ran the first tank of gas thru it. I went to start it up and it was hard to start, once it started, it revved like before and would die if I gave it any throttle, the idle seemed to be stuck on high idle. So, given that the only thing different I did was to open the gas tank to add gas and then seal it with the gas cap, I loosened the gas cap and the gas seemed to start to pour out under pressure. "What is the deal?", I thought. Anyways after I let the pressure out of the tank then the engine revved down and began running normally (I could give it throttle). So, is the "new" gas cap also defective or is there something weird going on? Why, after adding gas to the tank, do I have to install the gas cap in a certain position on the tank or else I'll have problems?
 

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sounds like you have a air lock in the tank. your cap is not venting
i have had the same problem with a flymo with a tecumseh av600 on it
hope this helps
 
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