Shindiawa Line Trimmer, Weak, Slow RPM at Full Throttle?

Discussion in 'Mechanic and Repair' started by D_C, Sep 22, 2009.

  1. D_C

    D_C LawnSite Member
    Messages: 4

    My Shindiawa Line Trimmer is weak, and RPM is slow at full throttle.

    New spark-plug, New fuel, in-tank fuel filter flows, relatively new carburetor, clean foam filter, flywheel/magneto-pickup is clean.

    It starts and runs, but even at full throttle, RPM is slower than usual and the trimmer head is easily slowed during use. The carburetor butterfly is opening and closing fully with the trigger control.

    RPM picks up when I spray tiny blasts of PB Blaster Small-Engine Tune-Up.

    What is likely wrong and how can I further test/diagnose?

  2. Breezmeister

    Breezmeister LawnSite Bronze Member
    Male, from South Jersey
    Messages: 1,734

    When was the last time you cleaned out the exhaust port and removed the spark arrester screen ?
  3. cbegap

    cbegap LawnSite Member
    Messages: 141

    Yea I would check those two things ASAP. I just pulled the muffler from my Echo 265T today and the spark arrestor was fine but the exhaust port was really restricted. I had used the PB Blaster tune up down the spark plug hole before so I was surprised that there was still so much carbon still there after using that stuff. So after I pulled the muffler I scraped as much as I could with a screw driver and then turned the trimmer upside down, put the piston up past the port and then filled the port with the pb blaster tuneup and let it soak but didn't let it dry out. It worked well because the trimmer now works like new.
  4. D_C

    D_C LawnSite Member
    Messages: 4

    Thanks. It has been a while since I checked it, and I will do it ASAP, but if that is the problem, why does it speed up only when I spray PB Blaster Small Engine Tune-Up, then once running just fuel/oil mix, it slows back down.

    Oh well, I'll check/clean the screen and let you know.

    Derek C.
  5. Breezmeister

    Breezmeister LawnSite Bronze Member
    Male, from South Jersey
    Messages: 1,734

    Just be careful using a screwdriver.
    ericg likes this.
  6. D_C

    D_C LawnSite Member
    Messages: 4

    I pulled the screen and then the entire muffler.

    It was a bit dirty, but did not appear to be particularly bad/blocked. I cleaned (scraped carbon out of) the cylinder exhaust port, then cleaned the spark-arrester screen and muffler with Oven Cleaner, solvent, soap & water, etc. It is very, very clean now.

    Will try starting/running the unit in the morning. Hoping for the best (that that was the problem,) but I'm not confident that "screen blockage" is the cause.

    Will let everyone know the results as soon as I test run.
  7. D_C

    D_C LawnSite Member
    Messages: 4

    Well, I started the trimmer this morning. It started first pull, but instantly died. I fussed with it some more and got it running.

    Had to play with the carb mixture adjustment and let it warm up, but it seems to be running back at full RPM.

    Looks like you were right. The arrester-screen was dirtier than it looked. Clear enough to start and run at low RPM, but dirty enough to keep it from running at full operating speed.

    I had cleaned it in the past few months, but it is getting older and must be fouling quicker than it used to.

    In any event, Thank You very much for the correct advice/diagnosis. :)
  8. Alan0354

    Alan0354 LawnSite Platinum Member
    Messages: 4,450

    I am curious on about how many hours of running before you have problem of the stuff buildup in the exhaust port? Hundreds of hours or less?

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