String Trimmer Carb. Problem


Old 02-16-02, 07:21 AM
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Join Date: Sep 2001
Location: Middle TN
Posts: 222
carb for string trimmer

Where can I purchase a complete carburator for a string trimmer? I've tried having it rebuilt, but it never seems to last. It is an IDC brand, which used to be Ryan, I believe. The model is a 500 Supreme.

Thanks in advance.

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Subject wording edited to consolidate and clearify topic.

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Last edited by Sharp Advice; 02-16-02 at 10:23 AM.
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Old 02-16-02, 09:20 AM
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Look for a brand name on the carb like Zama or Walbro.

You will have to look all over for other model numbers
or letters like Zama C1U 35 or Walbro WA155 etc.

Any mower shop should be able to order one complete for

But I must ask why? Are you saying that once it has been
rebuilt, it works fine for a week or two then won't start
one day?

Or that it always runs erratic and the mechanic tells you that it is the carb again? If that is the case, it may be something else.

I would hate to have you buy a new carb and get the same results, as a new carb may be $50 or more.

Let us know.

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Hi: Fish

Thanks for assisting with accurate information and professional replies to questions. Greatly appreciated.

Your reply was slightly edited.
Mostly because I need the practice...

Last edited by Sharp Advice; 02-16-02 at 10:36 AM.
Old 02-16-02, 10:19 AM
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Question More Detailed Information Requested

Hello: nashcat

Fisher states excellent points and asks an important question that needs to be asked and answered, in order to help determine the exact cause of the problem.

Who rebuilt the carb and why was it rebuilt?

What were the prior engine problem symptoms?

What are the current symptoms?

Knowing these facts, it may not be necessary to replace the current carb and or rebuild the current carb. The problem may not even be carb related.

Kindly use the REPLY button to add additional and complete reply updated information. By doing so, your topic will remain active and at the topic of the forums list of questions.

Doing so would greatly improve our chances of offering you corrective, helpful suggestions and advice, technical problem diagnosis assistance, professional repair methods, proceduers and technics, possible parts causing the problem your requesting.

Any and all additional detailed information you can provide may help to expose a clue regarding the hearters current problem and help us to determine the exact repair to the problem.

Your assistance in this matter would be beneficial.

Read the manufacturers online web site for product information, problem solving methods, disassembly, reassembly methods, repair proceedures and instructions, pictorials and schematics, which may be available online.

Lawn mower shops and or small engine repair shops can also help determine what the possible problem may be. Bring the year, make, model and serial numbers and stop in at the store. Parts and repair manuals are also available at these stores. Locations can be found in the local phone book directory.

Check the recent postings and ARCHIVES, within this forum, for other postings on your topic, specific appliances problem or conditions and read the replies offered. Chances are the topic, condition and or problem has already been covered in complete detail.

Your consideration in this matter would be greatly appreciated.

Regards & Thanks
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Old 02-16-02, 01:07 PM
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OK, I'll try this again. The carb is a Walbro WT148A, and has a 8MM intake and a 14 MM butterfly. It has both high and low speed adjusting needles, with the low speed being a air bleed type as opposed to a fuel metering needle.

I have had it rebuilt twice at two different shops with the same results. After a rebuild, and with a fresh plug, it will start and run, although not easy to start. After a using it a couple of times, it gets harder to start, appearing flooded, with the choke on or not. I can adjust the needles and get it to start, but then must readjust them to get it to run correctly. After adjusting, it will idle, then accelerate, then return to idle, with no problems. It is not loading the crankcase with excess fuel during idle, because the throtle response is quick. On the high speed needle, I am running about one quarter turn, rich, from the max RPM setting, not wanting to burn a piston. Fuel tank has been removed and cleaned, new fuel line, new intake filter, cold beer, and nothing seems to help.

The guys at the shops want to rebuild it again, but won't guarantee the work, saying "You might need a new one." But they are reluctant to sell me a new one if it just needs rebuilding.

I think that maybe I have a cracked housing, or maybe a clogged passage that we cannot get clean. I was hoping to find a online source for a new carb instead of paying the price that they want locally. One shop wouldn't tell me the price, saying that he would sell me a new trimmer for less than a new carb would cost.

Thanks in advance
Old 02-16-02, 06:14 PM
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Hello: nashcat

Based upon the updated additional information provided, there may not be any problem with the carb or the engine. You stated that the engine runs fine once adjusted.

However, I have now have to assume that the engine is often simply difficult to start, since questions # 2 & 3 were left unanswered.

If this is the case, try adjusting the throttle position from the manufacturers recommending procedures to half throttle or idle speed at start up. Some engines with low compression start easier this way.

Other small engine service and repair professionals, may have experience with the engine brand or equipment used, alternate suggestions, advice, opinions, test and repair procedures and methods.

Check back several times for additional replies.

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Old 02-16-02, 07:13 PM
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Looks like everyone has covered the bases here, But I will add that if the trimmer has been used a good while, it probably won't warrant the new carb....if that's the problem. You might have low compression, as Tom mentioned. Ryan/IDC isn't top of the put it mildly, lol. You could buy a new carb and the rest might not last a month, but then again....?
Old 02-17-02, 05:40 AM
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Oh, the Ryan/IDC sold also as Ryobi and many others. I know you didn't ask for this but feel a need, before you spend any more money, to inform you that this engine is a very poor design that will be trouble as long as it will start. The top mounted fuel tank seems to cause this model to flood very, very easily. When starting you may try a no choke start if it will. Check the hex head bolts that hold the cylinder to the crankcase, I have found many of these with loose bolts. Also, and this may be out of the area of a DIY kind of repair but the setting of the needle valve is very critical. If its the slightest bit on the high side it will flood. I don't mean the carb adjusting screws but the internal needle.....Mike
Old 02-18-02, 06:15 AM
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I have also found the four screws holding the carb/reed plate against the cylinder to be loose several times as well as the cylinder bolts.I agree that if there is not compression in the cylinder your fighting a loosing battle.Often a lack of compression is miss leading and leads the owner to many cash machines !!
Old 02-24-02, 06:01 AM
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Join Date: Sep 2001
Location: Middle TN
Posts: 222
Found Carb

Just a post back to let everyone know how things went. I found a used carburator that fit the trimmer and rebuilt it. The trimmer starts and runs fine, now. I'm pretty sure that the old carb has a crack in the body and is slowly letting fuel leak by the needle when it isn't running. The top mounted tank sure doesn't help matters. This would help explain the hard to start condition.

To those who recommended not spending a lot of money on this trimmer, I'll explain my reasons. I have a new John Deere straight shaft trimmer with blade, string, and edger heads. This does 90% of my trimming work. The little IDC is what I use around my wifes flower beds, because it much easier to get into tight spots and doesn't wipe out the entire bed when I slip up. Also the curved head gets into tight spots easier than the straight shaft.

By the way, the IDC trimmer is now about 10 years old and still has good compression. It's never been run lean and I keep the carbon buildup out of the exhaust port, probably helping with the life of the engine. I hated to junk it before it was time.

Thanks, everyone, for your comments

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