# stihl br400 backpack blower



## oncewaslost1982 (Nov 14, 2006)

I am working on a stihl backpack blower for a freind of mine. I have taken the carb off and cleaned it out. The gaskets in the carb are in fine shape. I messed up the one between the carb and manifold so i replaced it. I also put in a new diamond fire plug. Well now the thing will not run at anything above an idle. The adjustment screws only allow you to move them about an 1/8 inch either way. What would be causing this thing to run like this? It ran better before I cleaned it up.???


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## geogrubb (Jul 28, 2006)

Since you have had the carb off, check the travel of the throttle linkage to see if it is moving to give you full throttle. Have a good one. Geo


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## oncewaslost1982 (Nov 14, 2006)

Yes, the throttle is working properly. It is just dumping on the gas when I try to run it at full throttle, does that make sense? When I squeeze the throttle it will try to rev, but cannot because it appears to be getting way too much fuel, I can see it spraying out of the carb, kind of like a mist. Could it be getting way too much fuel some how? The only adjustments you can do to this carb are 2 little red plastic screw inserts and they only move 1/8th of an inch either way, ive tried playing with the settings of them and it is not helping at all. Can someone tell me whats going on with this crazy thing!? Thanks so much.


Justin


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## 30yearTech (Sep 14, 2006)

Check the muffler and exhaust ports for carbon, any restriction in the exhaust will cause an abundance of fuel to spray out of the carburetor and keep the engine from building any substantial rpm's


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## justin3 (Apr 10, 2007)

Ive learned that no matter how good the gaskets look, always replace them, especially on your style carb because of the fact that it needs a good seal to be able to suck fuel into the carb without the use of gravity. Like 30 year said, it may be an exhaust clog. I worked on a craftsman trimmer not to long ago with the same problem, it turns out the plug was old and the muffler was clogged with carbon and old oil. Looked as if the owner ran motor oil instead of 2-stroke oil with the gas.


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## Tranny Car Man. (Jan 8, 2006)

Iv had many a Stihl weedwacker's to chainsaw's with plugged spark arrester's.Take it out and clean it and it will run like new!!!!!.Too rich mixture's.And also other brands with the exhaust port pluged with carbon.


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