Troy Bilt Backpak Blower TB4PB -acceleration problem


Old 07-30-14, 04:58 PM
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Troy Bilt Backpak Blower TB4PB -acceleration problem

Hello everyone.

1st post seeking advice - guess that qualifies me as a 'newbie'

I have a 4 year old TroyBilt TB4PB backpack blower with acceleration issues. The back story is it would crank, run for a few seconds and then die. I suspected carb issues and the local repair shop said not worth the price of repair.

I found, ordered from eReplacementParts a new MTD carb ($37 + shipping) for the unit and have just installed it. The unit now runs, but with a caveat.

The unit cranks right up and idles fine. On acceleration however, at full throttle, it loses power and will die. The unit will run at about 3/4 throttle. It will crank right back up. This behavior occurs with or without the air filter attachment in place. I've checked throttle cabling and that is proper. I've noticed something that may be significant however and leads me to think perhaps a vacuum/fuel line issue.

When the unit is sitting in it proper position, and I accelerate I lose power/acceleration when going to full throttle.

If I tip the unit where gas lines are parallel (tip on side a bit) it will accelerate, (about 3/4s) and hold that 3/4s acceleration, but going slap dab full throttle kills the engine.

Is this a vacuum / gas feed issue ? I do plan on replacing the 2 gas lines Saturday to see if that helps/corrects is issue.

Any advice,comments, suggestions will be greatly appreciated. Yes new blowers aren't to expensive, but these are fiscally responsible times

Thanks and Best Regards to All !

Bill Watkins -
Charlottesville, Virginia
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Old 07-30-14, 05:14 PM
Join Date: Jun 2006
Location: United States
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I think replacing the fuel lines might cure it, however while it is running spray/dribble some carb/brake parts cleaner behind the carb and along the mating surfaces, if the engine tempo changes you have an air leak and can take tha appropriate action. Have a good one. Geo
Old 07-30-14, 05:19 PM
Join Date: May 2006
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See if you have any mixture setting screws - usually a high speed (H) and a low speed screw (L). Sometimes there is just one for high speed. Adjust the high speed screw in until lightly seated, then back out 1 1/2 turns. Then hold the throttle wide open and adjust the screw for max rpms, then out 1/16 of a turn.

At that point it should accelerate well. If you still get a dieing out, spray some WD40 around seals and gaskets. If the rpms varying in response you have a vacuum leak.

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