Engine dies

Discussion in 'Mechanic and Repair' started by kmans777, Apr 24, 2006.

  1. kmans777

    kmans777 LawnSite Member
    Messages: 2

    Hi all, first time poster. I have a Ryobi trimmer plus with the curved shaft. Several years old. The only model number I see is 725R, 31CC. Looked on the Ryobi site but no help there. I am a mechanic by trade but no experience on these engines. Trimmer started off with wanting to die out when pulling the throttle trigger. Not always, a couple of times then it would clear itself. Now when I start it, it's like it just burns the fuel from priming then dies. Prime it again and starts back up, then dies. I've taken the carb apart and all looks as it should. Seems to run fine as long as it has fuel. Fuel starvation seems to be the problem but the lines appear to be clear and fuel runs out of them when disconnected. Any help appreciated.
  2. oldrustycars

    oldrustycars LawnSite Senior Member
    Messages: 301

    the additives in the fuel deteriorate the fuel lines. running will suck the lines closed. no one will have ryobi parts, its a homeowner machine, and at 59 bucks you cant soend much shop time fixing them, so they dont bother with the parts. you may be able to match up lines from something else. stihl has a few sizes, and any mower shop should have Tygon brand line that may work. i also have a ryobi. a straight shaft i got from 89 at sams club. i have 4 years on it, and know its on borrowed time. someone on here brought up that these cheapo trimmers are designed to run about 20 hours.
    by the way, i just got done with 3 stihl machines with the same problem. fuel line fixed all three, but i also rebuilt the carbs at the customers request.
  3. newz7151

    newz7151 LawnSite Silver Member
    from Tejas
    Messages: 2,419

    Any MTD service dealer should be able to get the fuel lines for that Ryobi (now, the newer ones, you'd have to be a Homelite dealer as the new Ryobi is a Homelite in a different case). Also, with that age on it, even though you took the carb apart and it "looks" ok, isn't good enough. If you really want to fool with it (read: have too much time on your hands), take the carburetor to a dealer and let them look up the Walbro or Zama rebuild kit number. Partsmart shows part numbers for the fuel line kits, but you'd probably be better just trying to "close match" hoses. You may have even managed to lose some of the intricate parts of the carb. when you took it apart.

    Heck, save yourself some grief and about $20 and buy a new trimmer.
  4. kmans777

    kmans777 LawnSite Member
    Messages: 2

    Thnx for the replies. Didn't lose any parts. I've rebuilt a few carbs in my time. Don't want to throw something away when a lil time and a few bucks may fix it. That's why I'm here. I'll check the fuel lines. Question about the lines, There are 3. One runs from the gas tank to the priming bulb. The second runs from bulb to top left of carb. The third runs from tank to lower right side of carb. Do both lines feed the carb? One for priming, the other for when the engine is running? Or is the one from tank to carb a return line of sorts?
  5. Jman

    Jman LawnSite Member
    Messages: 217

    The third line is a return back to the tank from the carb. When you push the primer, all it does is fill the carb with fuel, it does not acually prime the engine. It sounds like the carb does need overhauled.
  6. lawnmaniac883

    lawnmaniac883 LawnSite Silver Member
    Messages: 2,613

    Make sure the bolts that hold the top end to the bottom have not backed out. They should be a #3 torx fitting IIRC.

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