Help with Stihl BR420 blower!

[BiodieselNC]

Alright guys, i know this isn't a chainsaw..... but i figure you guys probably know more about 2-strokes than the landscaping guys. Anyways, i have a Stihl BR420C backpack blower that was manufactured in 2007. Only thing i have done is put a non-catalytic muffler on the blower. Blower has always run fine and starts within 3-4 pulls. I never really have any problems with flooding it as I am quick to turn the choke off after the first pop. Basically a good running blower.

Well, i let the blower sit for about 2-3 weeks without using it, and since then i have not been able to get the blower running. First thing i checked was spark and compression. I have an inline spark tester than i have used on other saws, etc. and it lights up just like it would on any of my other running equipment. I checked the compression and she pulls 140psi (which should be enough, right?). Although my gas is clean and i use fuel stabilizer, i went ahead and took the carb apart and she was as clean as a whistle. I didn't suspect the carb as you can smell fuel after 1 or 2 pulls on choke. But went ahead and crossed this off the list. Next i took the coil out, which was clean, but lightly sanded it and the flywheel, then put it back on and re-gapped it. I also have tried 3 different, brand new, properly gapped spark plugs.

So it has fuel, compression, and spark. I am thinking the timing must be wrong Where do I go from here? New coil? Thanks for your advice guys!

-Ben

 

[gmcman]

When I bought my 420, the dealer sat the blower down, looked me in the eye, and said...."It floods easy, it floods easy, it floods easy"

I always remember that, and one time I forgot to either turn it on, or choked it too much when slightly warm, but it filled up with fuel.

If it has spark, make double-sure the plug is dry, worst case...swap to a clean, dry plug.

I have since sold it but if you start hammering on the cord....it will likely flood.

 

[Steveo_supremo]

They do flood easy. I would lock the throttle wide open and pull pull pull. I bet she fires.

 

[maestro]

Every blower I service for landscapers has a clogged or clogging spark arrester screen. Check that and if it's clogged, use a propane torch to burn off the carbon. Also check the fuel tank vent and make sure it's not dirty.

 

[om21braz]

So it has fuel, compression, and spark. I am thinking the timing must be wrong Where do I go from here? New coil? Thanks for your advice guys!
-Ben

Everyone is spot on about the flooding. Having fuel compression and spark - there's one more thing I'd - air. Does'nt happen often, but check the filter to see if it is acceptable shape.

 

[BiodieselNC]

When i cleaned the carb, i went ahead and put a new fuel filter on it, even though the other one was fine, just to cross it off the list. I also removed the spark arrestor screen months ago, long before this problem happened.

I have had this unit and other units flood, but i really don't think this is a flooding issue. In the past 2 weeks of trying to start this thing, i have not ever heard one "pop" and after 5-6 pulls with the choke on, i will take the choke off and pull the plug and pull the motor over a few times to clear out all the fuel. I have flooded it before and this does not appear to be a flooding issue.

Back to timing, is there any way a coil could make a good spark but be off time?

 

[gmcman]

You say you changed the fuel filter.....what kind did you put back in?

Where did you get the filter?

 

[boutselis]

I have bought 2 br 420's super cheap for parts. Both owners claimed they would not start and they didn't want to pay to fix them.

Both started for me.

Clean the plug (Wether its new or not) like they said. Floods super easy.

No more than 2 pulls choked. Whether it kicks over or not. If you kept pulling and forgot to take it off choke you can end up with a wet plug.
If it doesn't start in the next couple of pulls turn the idol screw in so it would have a fast idol and pull it un choked, throttle off, until it starts. 4 weeks is no time for a stihl anything to sit un used and then not start. It has to be something simple or the biggest coincidence ever.


Could you have screwed up the carb when you cleaned it? The metering lever is very very touchy on most year br 420's.

 

[gmcman]

+1 on the spark arrestor screen, definately clean it just to cross it off the list.

 

[BiodieselNC]

Spark arrestor screen is GONE! it was gunked up but now she's completely off. I got the fuel filter from the dealer, i'm trusting he gave me the right part. Again like i said, the fuel system was unbelievably clean that is why i pulled the carb just to check. But i had tried for days and day prior to pulling the carb off, I am pretty confident i didn't mess anything up when i took it off (have done lots of other carbs). I tried to pull it 2 times like you said with the choke, then take the choke off and continue to pull. But again, every other time i have ever started this blower I wait for the first "pop" and then immediately turn the choke off. I have not heard a pop in 4 weeks!

I have broke the rope twice and even just yesterday broke my Elastostart handle so I am def. pulling it fast enough!

 

[PhilKawasakiuser]

I an not totally sure but I don't see why it cant still create a spark and have the timing set wrong. I hate using it often but a small shot of ether will almost always get it to atleast try turning over. I always give my 2 strokes a couple good shakes to make sure the fuel is mixed up properly. If you use your equipment often and don't store your gas for more than few months you really don't need to use fuel stabilizer but it don't hurt. There should be two notches somewhere inside that you need to align to set the timing in my experiences. You might have the magneto put on in reverse also. I have seen this problem fixing motorized bicycles where the user tried to solve a small problem but instead created another one. I technically am not a mechanic but still have successfully fixed several small motors after a just fixing a couple with my neighbor who is one.

 

[PhilKawasakiuser]

also make sure your gaskets are put in correct. putting it in upside down would be a reason for it to not fire up. On the inside of the carb usually on the bottom is a small opening that better be aligned with the one in your gasket. My blower main blower is about ten years old and had set for probably about a year before I purchased it listed on ebay as for parts only planning on using the tank, spark plug and straps but to my delight when I opened it up I was able to get it running within about 8 minutes and make it running just about perfectly in under a hour. It probably wont solve your problem but I like to soak the muffler in motor oil occasionally for a good 24 hrs to make sure its nice and clean. My Stihl weed eater I just got a week ago also listed as for parts fired up after a good cleaning even thou the muffler has a few holes in it and is caked over with rust. Its main issue was the carb was bad. I put a carb from one of my ryobi's on it and it ran like a champ. I also had to repair a crack 5 to 6 inches long in the gas tank. It sounds bad but I used a soldering gun and melted the plastic a bit while pulling it over the crack and that has worked for atleast 4 hours of use now without any leaking. It seems to have solved the issue for atleast the time until I get the correct carb and a new tank in the mail which should be in the next few days. It fires up usually within 2 pulls. My poulan 42cc chainsaw takes 1 to 2 pulls to warm it up and it takes off the next one often no matter how the choke is set and has so far every time for 2 years now excluding needing new fuel lines.

 

[lone wolf]

Did you try a fresh plug with a small shot of gas in the cylinder? It should pop or run a second.

 

[STL028]

I have the same blower. Mine would not start a couple of seasons ago and it was a wire that had pulled loose off the coil I think it was. It was connected by a spade connector. I actually had to splice the wire to make it longer to keep it from pulling off. After that, it starts fine.

 

[PhilKawasakiuser]

I an not totally sure but I don't see why it cant still create a spark and have the timing set wrong. I hate using it often but a small shot of ether will almost always get it to atleast try turning over. I always give my 2 strokes a couple good shakes to make sure the fuel is mixed up properly. If you use your equipment often and don't store your gas for more than few months you really don't need to use fuel stabilizer but it don't hurt. There should be two notches somewhere inside that you need to align to set the timing in my experiences. You might have the magneto put on in reverse also. I have seen this problem fixing motorized bicycles where the user tried to solve a small problem but instead created another one. I technically am not a mechanic but still have successfully fixed several small motors after a just fixing a couple with my neighbor who is one.

New update I have now had this blower for over a week now and it always starts up within 4 pulls usually on the 3 since there is no primer bulb and the first few is just getting the gas up to the carb. Its quickly becoming a mainstay piece of equipment now for me. I may have paid a bit much since its old and was 82 dollars and has no air filter which now looks a bit strange since I actually home made mine out of some semi fine air conditioner filter material for a LG portable ac that burned up and a lid for a large box of slim jims found in my driveway. It does work pretty great tho and seems to catch anything that would potentially be a issue. If I had to say something bad it would for sure be that it uses a bit more gas than my Kawasaki BR700 which only cost me luckily 35.50 and another 20-25 in parts that were missing. It always starts within 2 pulls even when its sat for a few months. At these prices since I will admit I am cheap since its the time of year that its over 100 degrees every day and usually 45 to 90 percent humidity by sometimes as early as 9:30 a.m. AND it was worse last month usually 106-112 before noon and until 5:30 or even 6:45. The low is often in the low 90 occasionally mid 80's and there is next to no work available this time of year and what is available doing landscaping either is dangerous in most sane peoples opinions or miserable beyond belief and 10 a hr unless you are climbing large trees is the highest landscaping pay normally available and competition is intense for work sadly to. After the middle of October to late April seems to be the best time for work here in Tucson, Az. I would like to get certified for climbing tall trees right now I am not and mostly self taught from books and video's. I will probably take care of that in a month or two when its actually seriously helpful($$$) I have possibly to little of a fear of heights partly since I have been a fairly serious rock climber since I was 8 or 9 yrs old. Now I recently just turned 33 and my current harness has become to tight in the waist to be any use anymore. I have a 32inch waist and its max is 30 I believe my old shoes still fit like a glove and so do my Scarpa/Fambino leather boots thankfully since I wouldn't want to have to pony up the cash for a new pair. My old Vasque sundowners also fit still which I got at 17 yrs old. I like being able to work my own hours and lately have started fixing my neighbors old gas tools that they are fed up on and am starting to think that I can make more doing this than anything else especially now. I also got a great echo 2100s something 23.8cc for a great price of 3.25 and got it running for another dollar and a half. A somewhat friend or atleast he calls me that just offered me 120 for it if I throw in one of my dozen gas cans and give him a warranty or atleast promise to replace the fuel lines for the next couple of years for a reasonable price like parts plus a maybe a pack of ciggs(6.50) and the primer bulb since he has had bad luck with gas tools since he lets them sit fueled up for several months often 6-9 and then expect it to start the first pull and everything to be as he left it. I hope he buys it for a close to a hun and lets me do the work at ten a hr instead of him possibly messing it up and then blaming me. Sorry for the wordiness....I wanted to ask since I recently purchased a 45 husqvarna the red for 60, an 23 compact for 55 both look like they were never really used especially the compact . The 45 has no bar and chain but otherwise is pretty complete(no case). Does anyone have experience with either of these and advice on how they handle heavy useMy other gas chainsaw sadly is a poulan wildthing 42cc(It works descent for about 35-45 minutes and then the chain becomes extremely loose within under a few minutes more. My cheap craftsman electric which came from a goodwill goes atleast a hr before this happens. Does anyone have any suggestions on how to keep it from becoming so loose in such a short time. With the Kawasaki KRB700 I also had to splice the wires for turning it off using the correct hand controls. It does look a bit like at one time it might have been a flaming ball of fire which the user quickly dropped cracking part of the F side of the housing which was luckly a easy super glue and baking soda fix on one side and soldering gun melting and pulling together on the inside. The part that I believe is called a elbow connecting the red housing to the wand is made out of 4.?? inch flexible hose and the uppers made out of a piece of PVC and the wand from a broken cheap electric blower my dad bought at goodwill for a couple dollars not realizing that it had no compression is attached with duct tape I think that the Stihl BR420 is more than a comparable replacement for his worx brand electric blower since I live in his guest house I taught him how to use properly and keep fueled up. I do end up being the only one who uses it no suprise. I use a 40-1 mixture with just about all my gas 2 strokes and it seems to work well so far. Does anyone think that this isn't a good idea. I also always use 91 or 92 octane gas and husqvarna oil or other brand name 2 stroke oil. The mowers were inherited from my dads dad They are both practically identical and were my inheritance I guess plus some ww2 and korean war medals my dads dad left me since I made him happy by making Eagle in Boy Scouts unlike my dad who was star or life which is practically as close as possible without being. Sadly I think that might have been one of the last memories he had of me since alzheimer's runs in the family so I have something to look forward to. In Scouts we took so much acid and smoked ourselves retarded basically on some of the local backpacking weekend trips and I never had any issues with the adult leaders doing anything about it besides asking that they were included in these activities and not kept out of the loop. I barely smoke now maybe a few times a month at most since it becomes used primarily for taste and flavor more than effect. Spacing things out makes it more special and interesting. It also saves a little money but not much since its all over here now and the prices been more than cut in half outside of the dispensaries since it became medically excepted and prescribed for a hundred and 50 dollars I believe yearly which is long overdue. Its also shut down the mexican cartels from selling there bricked garbage here at all sadly they have resorted to spreading more dangerous substances around and probably addictive. They I think are craftsman or something basic like poulan and have a briggs an stratton 4stroke powering them both.

 

[PhilKawasakiuser]

The stihl also after running it a bit now is working wonderfully considering its age. 3 pulls usually is all it takes since theres no primer bulb on mine the first pulls just fill the lines with fuel. The owner said it doesn't work just like my Kawasaki KRB700 and some other gas motorized tools. I don't get it since they work great for me. What were these people doing wrong maybe the choke setting I don't know. I think its bizarre how many people give up on there gas tools and blame the tool saying its a parts piece or basically junk and they fire right up for me.

 

[sundance]

Spark arrestor screen is GONE! it was gunked up but now she's completely off. I got the fuel filter from the dealer, i'm trusting he gave me the right part. Again like i said, the fuel system was unbelievably clean that is why i pulled the carb just to check. But i had tried for days and day prior to pulling the carb off, I am pretty confident i didn't mess anything up when i took it off (have done lots of other carbs). I tried to pull it 2 times like you said with the choke, then take the choke off and continue to pull. But again, every other time i have ever started this blower I wait for the first "pop" and then immediately turn the choke off. I have not heard a pop in 4 weeks!

I have broke the rope twice and even just yesterday broke my Elastostart handle so I am def. pulling it fast enough!

I think the 420's actually have two fuel filters. Take a good look in the tank, if I'm right try changing the second one as well.

 

[PhilKawasakiuser]

I would put the choke inbetween fully open and closed a see if you can get it to find a spot where it feels like it belongs and then give it a few good pulls an if it starts change the choke to fully open

 

[PhilKawasakiuser]

Its going now by the way and doesn't seem to have any real serious issues also thankfully. Now I am currently just looking for a replacement for a old kawasaki KRB700 Blower and a Deere BP50 and BP40 air filters. Seems like its almost always something with old items like these and if it isn't it will be again with 6 months or less. If I don't get them in the next few weeks I will probably end up pulling a different one from a dead blower and using it in place of the originals. Thanks for any help offered by the way.

 

[Mad Professor]

Every blower I service for landscapers has a clogged or clogging spark arrester screen. Check that and if it's clogged, use a propane torch to burn off the carbon. Also check the fuel tank vent and make sure it's not dirty.

Yup, had that with my BR 400.

Anything that won't rev check the screen.