Ryobi 4 cycle carb problems


Old 08-18-09, 04:14 PM
Thread Starter
Join Date: Aug 2009
Location: New Jersey
Posts: 2
Ryobi 4 cycle carb problems

My ryobi 4 cycle weed trimmer wont start again. I've rebuilt the carb twice. It always starts after the rebuild but after storing for a few weeks the next time I try to start it, it won't start. If I prime the carb it starts right up and runs the prime out then quits. It appears that the carb stops supplying fuel. Sometimes, if I bang on the carb it'll run, then, after storage, it won't start again. I wonder if anyone has had the same issue and knows what is causing the problem or might know what is causing it to stop pumping after short periods of storage.
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Old 08-19-09, 07:59 PM
Join Date: Jul 2005
Location: Texas
Posts: 205
I had one that would not stay running,after I had rebuilt the carb.If this is overhead valve trimmer,check the valve clearences.Hope this helps.

Old 08-22-09, 11:09 AM
Thread Starter
Join Date: Aug 2009
Location: New Jersey
Posts: 2
Don't think valve clearances have anything to do with it since it runs perfectly after disassembling and reassembling the carb. After a week or two of storage the carb stops pumping fuel. I have read that sometimes the needle can stick to the seat preventing the diaphram from opening it. However, on my engine this doesn't seem to be the case. At least it appears that it isn't sticking to the seat when I take it apart.
Old 08-22-09, 07:52 PM
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Join Date: Feb 2005
Location: canada
Posts: 1,561
When you say you rebuilt the carb,, Did you install the new diaghragms & gaskets,, or use the old ones?? Also if you did install a complete kit, did you adjust the height of the meetering lever??? You didn't say what carb you had, but the carb manufacturers have excellent manuals on there sites....I trust you have verified the fuel lines & the primer bulb are in good shape with no holes & the filter isn't blocked???? Roger
Old 06-27-11, 02:50 PM
Join Date: Jun 2011
Location: USA
Posts: 1

I have the exact same problem with the fuel lines - and brand new out of the box. I returned the trimmer shortly after purchasing it because I thought it had a manufacturing defect. Home Depot switched out the power head with a new one from a box they had on the shelf, but I had the exact same problems with the second one. I also had problems with the engine sputtering constantly while the engine was hot. I tried different oil levels, thinking at first that might be the problem (by the way, they could have a better way to do this - It's by no means accurate).

When the trimmer is cold, it always starts up easily and even idles well. But once the engine gets hot, say after 10 or 15 minutes of use, it's difficult, if not impossible to restart. I've tried things like slightly opening the gas cap to release a possible vaccum problem, but that had no effect. I noticed that the fuel primer bulb is useless when the engine is hot - it's like there's a hole somewhere in the fuel system. It's pretty obvious that this is the problem, as no fuel is getting to the carb. But when the engine is cold, the primer bulb works as it should. I've had these same problems with Ryobi's 2-cycle engines, so to me it appears to be inherent to the design of the fuel supply system. It's not rocket science - seems there should be an easy fix, and Ryovi certainly should address the issue.

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