Echo PB-403T backpack blower issue

wakebdr(ATL)September 7, 2010

I've got an Echo PB-403T backpack blower that is exhibiting a problem. As I throttle it up, it "accelerates" (for lack of a better term) until it gets to a certain point at which time it seems like it wants to choke itself off. Before I took it apart and replaced the spark plug and cleaned the carburetor, it actually would choke itself off when running wide open. I can get it to a certain speed, but anything after that and it wants to die.

Any thoughts?

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Wake: It appears that although you have cleaned the carb , the blower is still starving for full at high rpm or load demand . Try checking the fuel filter for restriction or add fuel cleaner to a fresh fuel mix (to eliminate water fouling), approx 2 ounces let the unit sit approx 30 minutes then start it up and slowly to increase the Rpm until WOT is achieved . Perhaps some residual debris or gumming still restricting the fuel flow , if this does not restore fuel flow you may require jets removed and cleaner spray directly within the jets . Also check the intake manifold / carburator fasteners for tightness and Fuel lines for pinch condition should fuel cleaner additives not resolve your internal carb issue.

    Bookmark   September 8, 2010 at 5:34AM
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Also check the muffler and muffler screen for any kind of blockage. Steve

    Bookmark   September 8, 2010 at 7:31AM
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I'll try some new fuel with fuel cleaner to see if that helps any.

I visually inspected the fuel filter and it appeared to be extremely clean. Also cleaned the muffler screen as well, and it wasn't very dirty.

It's weird though. When I checked all the suspects the manual points to, they all seemed to be very clean, almost new looking. Now that's not to say there isn't something there I couldn't see, but they all appeared to be ok.

    Bookmark   September 8, 2010 at 9:49AM
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Tried new fuel mix with fuel cleaner and it got a little better, but not 100%. It still wants to throttle down, but not every time. Some times it will run at full throttle and others it won't. After a full throttle run, it's almost like it needs a rest at idle before it will go to full throttle again. I also feel some "hiccups" when it's running at full throttle too.

    Bookmark   October 1, 2010 at 6:41PM
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Wake: Your current description would indicate that your are on the right track . In some stubborn cases jet removal and high pressure carb spray eg: Berrymans-12 or Concentrated "Gunk Product" is required to further removal residual hardened varnish or debris within the Main Fuel Circuits. It would appear that your primary Primer or Starting "Idle" circuits are clear. The Hiccups that you describe I would think are from residual debris causing temporary or sporadic fuel restriction and sluggish throttle response etc. You may also have to actually dismantle the carb diaphram plate and check the inlet needle valve and diaphram for full range of motion and for small tear or diaphram stretching caused either from normal wear and tear (old diaphram) or extended ethanol based fuel usage. Secondary cause would be Electrical Coil Degradation , but normally a definite Engine "Miss" is identified with a Coil going South , which I don't think you are describing . I would say try the jet removal 1st and cleaning and tune to 1-1/4 to 1-1/2 turns out from closed . Let us know what you find Bro !

    Bookmark   October 1, 2010 at 11:40PM
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I adjusted the screws on the carb this morning and it seems to be running much better now. Don't want to speak too soon, but I hope that was just it.

    Bookmark   October 2, 2010 at 2:44PM
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Wake: Great to hear Dude ! Might take a tank for the treatment to further clear up all symptoms . The jet cleaning and tuning should break up any left over restriction and Performance should return to Optimum . It does not take long for ethanol or non ethanol based fuels for that matter these days to cause problems within small engine carburetor's when not used for any period without fuel treatments lol .

    Bookmark   October 3, 2010 at 8:46AM
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