Stihl leaf blower- running problem

[Plane Crazy]

I bought this RB 400 new, four years ago, used very little It began loosing high speed, I have replace the fuel line and filter. Cleaned out the muffler.
It starts right up, BUT, only if you leave it on full choke, and will only idle, try to increase speed , it dies...I took carb off and resealed, still no improvement.What can it bee.
Thanks for all replys,
Howard

 

[fordbroncodave]

i have the exact same one here. very nice machines.

anyways, i had the same problem. i could start it, give it a little throttle and it would die. it ended up being rust flakes in the muffler.

take the carb off and spray the whole thing with carb cleaner. blow it off with compressed air and then do the same to the inside and all the wholes.

get a new spark plug too

 

[GDA]

Sounds like it running with an air leak.

+1 on ^ suggestions to put in a new plug and really clean the carb and exhaust with carb cleaner. Also suggest you take a close look for gasket leaks.

 

[mrjsl]

My weedeater does the same thing when I haven't ran it in a while. I can usually get it going by playing with the choke and throttle, and once I get it to rev, I run it wide open as much as possible. Sitting up is what kills it.

 

[Major Ramifications]

Sounds like the mixture needs to be adjusted.

 

[pattenp]

Sounds like you have a high speed jet that's got some varnish build up. If you don't use gas stabilizer and run the fuel out at the end of each season this will happen. You need to take the carb apart and run some fine wire through the highspeed jet to clean it out. Spray carb cleaner a lot of times won't take care of the problem.

 

[fordbroncodave]

i have found these do need to warm up just a little at idle before they can take off at full speed.

best leaf blower of all time. (especially since i got 2 for free)

 

[adam728]

Sounds like it's time to clean the carb!

Most time's that a carb won't run without the choke it's got a blockage in the screen or in the high speed circuit. You can start by pulling the pump cover (the cast cover, single screw in center, not the stamped steel 4 screw one) and blow the screen out with carb cleaner. The right way to do it is to buy a carb rebuild kit, new diaphragms, gaskets, inlet needle/lever/pin/spring, and a screen. Tear it all down, clean it out, and reassemble.

Just hope it's not as dirty as the one below. This was actually returned by a dealer, marked as coming off a brand new, 0 hr unit when they recieved it, and that it was "made wrong". The carb was 5 years older than the trimmer it supposably came from, and wasn't for that model anyway. Some people are funny.

 

[bindernut]

Yep, sounds like it's time to clean & rebuild the carb. Be careful spraying jets & passages out w/ carb cleaner. An aerosol can has enough pressure the damage a check valve. NEVER use compressed air to blow out a carb.

if it had an airleak, it would run off choke. It would also run fast, and not idle down, or take a real long time to idle down.

 

[Plane Crazy]

THANKS, to Everyone, got it going again, it ran yesterday about 40' and quit
took it back apart,had more trash in it
went and got a NEW filter, after looking closer the old filter was coming apart.

Thanks SO Much again, amazing, starts with one pull, like it use too

Now I can finish my driveway to the shop.

 

[Scooterfish]

If I may jump in here. I have a BG 55 when fuel tank gets down to 1/2 empty it stalls out. I replaced the tube to the tank ( which often cracks) a couple of years ago and all was fine. Any thoughs on current problem? Thanks

 

[adam728]

Cracked tube again?

Does the unit recover if you open the gas cap? Sometimes the one-way duckbill can seal itself shut, then the tank starts to build vacuum as the unit runs.

 

[Scooterfish]

Adam, I never tried opening/ closing gas cap without adding fuel. It does have built up preasure in the tank when it stalls.
When it starts cutting out if I turn blower upside down it will run alittle longer, but still stalls with about 1/2 tank of gas. What is the one way duck bill and what do I need to do ? Thanks for any help

 

[adam728]

In the fuel cap is a small duckbill one-way valve, lets air in, but doesn't let air/gasoline fumes out. If the slit becomes stuck together the tank can have a strong vacuum created inside that will eventually starve the unit for gas.

Pressure build up is pretty normal. Gasoline will release a lot of it's lighter hydrocarbons when heated or agitated. Since the tanks on these are desgined not to let anything vent out it will build pressure.

I'm still thinking you have a bad fuel line, or the fuel filter isn't staying submerged in the gas. I would guess that it's independant of the carburetor, since it follows fuel level in the tank, and changes with position.

 

[Scooterfish]

Thanks Adam, The fuel filter is positioned properly. I will check the tank cap as there seems to be alot of excess presure to me. I will check the line for cracks again as well. I know you have make sure the fuel tube seats properly wher it fits into the tank.

 

[EdTheZ]

I have an Echo PB 603 and just had the same problem. Took me 2 days to determine it was the high speed jet. But they glue plastic caps on so you can turn the needles 1/2 turn but not remove them. The high speed needle was set maximum out (to the plastic cap stop) so I screwed it max in, then back to max out, then in, then out etc. as it was running. It ran better and better each time. Of course I made sure I returned it to the original position (max out).

So I suggest instead of rebuilding the carb, screw the jet in all the way (counting the revolutions). Then back out and back in and back out etc. Then all the way in and back out the number of revolutions you counted initially. This MAY alleviate your problem... it did for me!

 

[organ]

Good luck... if I was wealthy I'd chunk any weed eater or leaf blower the second it started acting up... save myself a lot of stress.

 

[Puzzaaa]

I have a homelite mighty lite 26bv leafblower that hasn't ran for a couple of years. I haven't ran it because the fuel line had rotted. I replaced the fuel line and tried to run it. When it starts after a couple pulls the engine revs up to max rpm on full choke then starts to die slowly until it's just barely running. And if I try to put it to half choke or run, it revs up to max then dies completely. It will only start on full choke. Any help?
Thanks

 

[Dust Devil]

You can spare yourself headache and time by just buying a new carb and new fuel lines if you let it set.

Carbs for most Stihl stuff are cheap $30 or so.

 

[Puzzaaa]

We'll I guess I'm going to have to get a new carb because I already changed the fuel lines. I had cleaned out the carb before and removed most of the gunk inside but I guess I'm going to have to get a new one

 

[spotco2]

Yup, new carb, plug and clean spark arrestor.

 

[SMKS]

We'll I guess I'm going to have to get a new carb because I already changed the fuel lines. I had cleaned out the carb before and removed most of the gunk inside but I guess I'm going to have to get a new one

But did you actually rebuild the carb with a new kit? Diaphram, etc?

 

[Dust Devil]

Yup, new carb, plug and clean spark arrestor.

Thats how we roll at the dealership.

Customers are most happy in the end that way.

 

[Dust Devil]

We'll I guess I'm going to have to get a new carb because I already changed the fuel lines. I had cleaned out the carb before and removed most of the gunk inside but I guess I'm going to have to get a new one

Pull the numbers off the carb and hit e-bay for a new one (unless you have a dealer nearby)

 

[Puzzaaa]

Thanks guys cleaning the spark arrestor helped it run on full choke better. It is usable on full choke for right now but I am gonna buy another carb online or at the dealership near me. Thanks for the quick responses.

 

[ZR900]

I have a 55 handheld. It wouldn't run except at idle. Every time I tried more throttle it killed. Old gas. Hadn't run since last year. I tried my standard fix....Seafoam. Didn't work immediately. Came inside to look online. Found this thread. Decided to check the gas lines and carb. It was filthy with oil encrusted dirt and grass. Blew it all of with carb cleaner and engine degreaser. Couldn't easily get the carb all the way off. Took out the needles and blew carb cleaner thru them. Put all back together. Still wouldn't run but it had signs that it might. Kept choking it and running the hi needle all the way in and out. Purrs like a kitten. I think the sea foam did it. Stuff is magical.

 

[pepi]

My weedeater does the same thing when I haven't ran it in a while. I can usually get it going by playing with the choke and throttle, and once I get it to rev, I run it wide open as much as possible. Sitting up is what kills it.

You are right there, high test gas will help there also, meaning use it. One saves nothing putting cheep gas in two cycles, does make your life a pain in the ***.

 

[justme-]

any carburetor engine that only runs with choke on has a clogged main jet. We don't clean/rebuild Stihl carbs at my shop - less work, less cost, and overall happier customers by putting a new one on. Labor rate for us to rebuild it plus the parts kit is usually pretty close to a replacement carb, then there's the possibility the rebuild was not 100% successful and needs to be repeated, or (on some carbs especially Zama and Walbro) a welch plug has to be removed and the passages under it cleaned more...now we exceed the replacement cost for the carb.

 

[rcorn1031_0]

I bought this RB 400 new, four years ago, used very little It began loosing high speed, I have replace the fuel line and filter. Cleaned out the muffler.
It starts right up, BUT, only if you leave it on full choke, and will only idle, try to increase speed , it dies...I took carb off and resealed, still no improvement.What can it bee.
Thanks for all replys,
Howard

I had the exact same symptoms on my FS90R string trimmer this spring .
Mine turned out to be the Plastic camshaft ate itself . This is not very difficult to replace , Depending upon your level of Mechanical know-how . you'll need a new camshaft, some high-temp RTV gasket maker and a valve adjustment service kit . The kit comes with the special feeler gage for adjusting the valve clearances .

 

[rcorn1031_0]

Good luck... if I was wealthy I'd chunk any weed eater or leaf blower the second it started acting up... save myself a lot of stress.

Like any good tool , Maintenance is required . Especially in this " Throw away " society . Carefully reading the Instruction manual helps a great deal . NEVER use CHEAP PUMP GAS . Also IF it is available only run " NON ETHANOL" Recreational Gasoline ( standard pump gas even the premium grades has 10-20 % ethanol in it . Ethanol will literally draw moisture right out of the air before your eyes on a humid day . I only run "REC-90" from a Local Shell station . I have seen more Negative than positive reviews of "Canned Fuels" so I avoid those as well .

 

[Caa311]

I run the crappy gas in all my sthil stuff and almost no maintenance. They run fine. I have lifetime warranty on all of it so I treat them badly. If you have the little plastic valve through the tank and it clogs you will go insane chasing the won't run problem.

 

[Caa311]

I run the crappy gas in all my sthil stuff and almost no maintenance. They run fine. I have lifetime warranty on all of it so I treat them badly. If you have the little plastic valve through the tank and it clogs you will go insane chasing the won't run problem. My br600 we replaced almost everything and it still wouldn't rev.