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Craftsman trimmer won't idle


mizzleman's Avatar
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05-17-05, 10:19 AM   #1  
Craftsman trimmer won't idle

Hello All! I have Craftsman 25cc line trimmer that won't idle. The part# for the unit is 358.795050, the family is ypwes.0214lt:em with a Walbro carb. I don't know the factory settings for the carb. Using the advice off of this board, I figured out that the unit runs best with L set to 2-1/2 turns out and H at 2 turns out. I guessed at the idle screw setting and adjusted it to 5-6 turns out. It will start and run easily. It won't run or idle at anything less than 50% throttle. This thing has not run particularly well since I bought it new. I took it back to a Sears repair place shortly after I purchased it. They just cleaned the carb (so they say). I have always used fresh gas, spark plugs and kept the air filter clean. Any help is greatly appreciated. Thanks.

 
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05-17-05, 08:08 PM   #2  
Posted By: mizzleman Hello All! I have Craftsman 25cc line trimmer that won't idle. The part# for the unit is 358.795050, the family is ypwes.0214lt:em with a Walbro carb. I don't know the factory settings for the carb. Using the advice off of this board, I figured out that the unit runs best with L set to 2-1/2 turns out and H at 2 turns out. I guessed at the idle screw setting and adjusted it to 5-6 turns out. It will start and run easily. It won't run or idle at anything less than 50% throttle. This thing has not run particularly well since I bought it new. I took it back to a Sears repair place shortly after I purchased it. They just cleaned the carb (so they say). I have always used fresh gas, spark plugs and kept the air filter clean. Any help is greatly appreciated. Thanks.
Sounds like a Homelite trimmer that I am working on. I have sprayed the carb with cleaner and put a different spark plug in it and it still will not run without giving it throttle. Well, I take that back, it will run for about 10 seconds after letting off the throttle. If I thank of anything I will let you know. Spark arrestor could be dirty or you may need to clean the carb or overhaul it. Good luck.

 
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05-18-05, 12:36 AM   #3  
Sounds like you're going to need a carb cleaning. You can try messing with the low speed screw a bit, but if it only wants to run at 50% throttle, then the low speed fuel circuit in the carb is probably restricted.


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05-18-05, 07:09 AM   #4  
Thanks guys. I messed around with it a little bit last night. I set H to 2 turns and L to 1/2 turn. It will actually idle if I hold the throttle at about 1/4. It had good throttle response from that position to full throttle. I agree Cheese, I think the low speed circuit has an issue. I'll probably disassemble the carb tonight and look at it.

 
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05-26-05, 04:34 PM   #5  
Hello all,
I finally got around to disassembling the carb. Everything looked in good order and was squeaky clean. I didn't take the bronze pieces out as I feared destroying them in the process. I used some carb cleaner on it as much as I could. I put it back together and have the same problem. If the throttle plate is 1/8" open or more it runs fine. The idle screw sets it about 1/16" open at 5-6 turns and will not run at all. Is it possible there is something in the passages of the carb I can't get to? Could the butterfly slip on the shaft and really need to be open 1/8"? Thanks in advance for the help.

 
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05-26-05, 11:51 PM   #6  
I can't see how the vlave would slip on the shaft. Have you checked the fuel lines to be sure one isn't sucking air? The primer? I think you might have an air leak, maybe even at the intake or crankcase cover. These things are built so inexpensively that problems can occurr just about anywhere, and they are hard to pinpoint at times.


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05-27-05, 08:09 PM   #7  
I took a look at the fuel lines tonight and they are airtight. When I use the primer bulb, there is fuel moving through both lines solidly. If there's a leak at the intake or crankcase cover, what would the best way be to find it? Can I put a thin coating of RTV on the crankcase cover and the air cleaner-to-carb cover (no gasket between them) and hope that gets it?

 
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05-28-05, 12:24 AM   #8  
You could try, but disassembly and visual inspection is about the only good way I know of to check for a leak. I believe it's either that, or still a carb problem.


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05-28-05, 07:26 PM   #9  
Thanks, cheese. I'll take a look this weekend.

 
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07-25-05, 07:17 PM   #10  
It's been a while, but I finally got around to removing the carb. I'm checking the fuel passages to see if there are any blockages. On a Walbro WT-520 carb, where does the fuel flow from/to on the low speed circuit? I'm looking specifically around the adjustment screw seat. I figured the hole at the bottom of the seat goes to the main jet, but what about the small hole in the side of seat? It's so darn small I can see it could easily get plugged. Also, if I take off the diaphram and gaskets, is it OK to soak carb overnight in carb cleaner? The carb cleaner I have is made by Gunk and specifically mentions no plastic or rubber. Are there any more plastic or rubber parts in the carb that could be damaged? Thanks for the input.

 
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07-26-05, 01:05 AM   #11  
There are so many variations of different carbs that I can't recall where the idle circuit is on any one of them off the top of my head. I know it enters the carb just behind the throttle plate on the engine side of the carb.

It should be ok to soak the carb overnight, but it's much longer than necessary. 30 minutes would probably be enough. I should add that I've never used that brand that I can remember, so you might check to see how long it is reccomended to let it soak and stick with that to be safe...unless someone else has used this brand and can add some input??


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07-26-05, 05:23 AM   #12  
I, too, don't know the quality or strength of the Gunk cleaner you are using but don't recommend soaking for more than 20-30 minutes. As long as all the gaskets and diaphragms are removed you should not get into any trouble with any other rubber parts in the carb. Based on the Walbro model # you gave, there is a rubber check valve but it is well supported and will not become deformed by soaking. Soak and use Walbro kit # K10-WAT. And depending on the condition of the carburetor mounting gasket, you may want to replace this as well...don't get into any trouble with air leaks.

 
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07-26-05, 07:15 AM   #13  
Azis
Is it just me or is everyone missing this:
I guessed at the idle screw setting and adjusted it to 5-6 turns out.
The idle screw sets it about 1/16" open at 5-6 turns and will not run at all.
Adjust the idle screw out until it no longer touches the throttle linkage plate, then adjust in until it just comes in contact with it. Make mixture adjustments for high speed and throttle response then adjust the idle screw in and see if you can get a normal idle speed. At the very least you should be able to adjust it to make it run on its own. It still may be a restriction problem if the idle can not be set low enuff, but there is not mention I see of this adjustment being made.

I have used Gunk products such as their engine cleaners with good results. If it says however not to use on rubber and plastic, I would head its warnings and not use to Soak but just to spray and clean. There could be plastic nylon or softer bushings on such as the throttle shaft that may not stand up too well.

 
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07-26-05, 07:57 AM   #14  
Az,
Actually, I did try those suggestions that you made. I may have been remiss and didn't post it. I have adjusted the low speed circuit anywhere from 1/2 turn out to 3 turns out and the idle speed screw either fully in or fully out and all the combinations in between. The 1/16th open I mentioned was for the throttle plate opening, so I know there's air going through. The results were the same. The unit would not idle at all, but at 50% throttle and up it runs great and good power. I'll try soaking the carb for 15 min. and see what happens. Thanks for the input guys.

 
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07-26-05, 09:15 AM   #15  
Azis
Glad the step was not overlooked and logic would state it had not been. Just without a mention one never knows. Hopefully the bath will do it

 
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