Stihl backpack blower lost about 1/2 it's power.

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It's a BR420C Magnum model about 12 years old (only used every few weeks).

I put in a new plug, new gas/oil mix, and tested without the air filter and nothing helps.

I use quality FD rated 2 cycle oil.


Any ideas?

Thanks!
 
Carb cleaned? Fuel line clogged? How does the compression feel when you pull the starter cord?
 
It feels the same when I pull it to start.

I am running my first tank of gas with carb cleaner and no different so far but I have just used part of the tank.
 
My echo was doing this ,and I added some seafoam. After adding the seafoam it started running like new again.
 
If I catch cancer, I'm gonna start drinking seafoam.
smile.gif
 
I know this is simple so chances are it was obvious enough to check - but did you make sure the intake for the blower impeller itself was clear?
 
Check the spark arrest screen. I'm sure it's never been checked in 12 years. Grab your propane torch and burn off all the oil on it and put it back. Some people don't run them (myself included), but they are there for a reason.
 
at 12 years old, the diaphragms in the carb are probably a little stiff, I'd rebuild the carb and clean the spark arrestor in the muffler at the same time. Just pull the screen out and burn it off with a propane torch.

Also a good time to replace the in tank fuel filter and inspect the fuel lines, they tend to get soft and gummy with today's ethanol blends (I've actually seen them melt completely)

For all the parts your looking at about $20-30 and an afternoon taking your time to clean the carb thoroughly.
 
Run som b12 chemtool from Walmart in your gas. It should clean it up and give it life again. Add a few capfuls directly to the gas tank along with fresh gas. Or go this route use a can of 50:1 Trufuel or same for few tankfuls.

I really suggest the chemtool route though.
It really works well. For less than $5 bucks a bottle you should be a bit happier as you won't have to get a new carb for it.
 
Originally Posted By: WhyMe
check and see if the exhaust screen is clogged.

+1
If the spark arrester screen is clean, pull the muffler and check the exhaust ports. Blowers are highly prone to carboning up the exhaust ports.
 
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1 Spark arrestor screen, clean it or toss it.
2 Rebuild the carburettor, passages get gummed up and pump diaphragm stiffen.
3 Replace fuel lines and filter.
 
I've been a big fan of Stihl's Ultra HP oil. A six pack of it will last me quite a while and I've never had any significant carbon buildup on any of the saws I run it in.
 
Yeah if the spark arrestor screen is clogged up, what oil and ratio are you running? I have never seen it clogged up when using Stihl or Echo oil, they burn too clean.
 
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