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View Full Version : Stihl BR 420 Blower Flooding


slawn
07-20-2007, 12:31 AM
I have a 420 blower that keeps flooding. I've took it to the dealer twice, and they have yet to find the problem. They last time they said it was probably trash in carb. It ran on the first yard this morning, second yard wouldn't start. I tried several more times throughout the day, flooded every time. Any suggestions?

thanks

JHugh
07-20-2007, 12:38 AM
What did the dealer do the two times? Did they just clean the carburetor or rebuild it? It may be leaking past the inlet needle in the carburetor. The metering diaphragm could be getting stiff and sticking the needle open. The metering arm may not be adjusted to the correct height.

slawn
07-20-2007, 12:55 AM
They just cleaned it. I think I'll get a kit and rebuild the carb see if that solves the problem.

thanks

Breezmister
07-20-2007, 09:12 PM
I have a 420 blower that keeps flooding. I've took it to the dealer twice, and they have yet to find the problem. They last time they said it was probably trash in carb. It ran on the first yard this morning, second yard wouldn't start. I tried several more times throughout the day, flooded every time. Any suggestions?

thanks

Probably trash in the carb ? Sounds like the dealer or the mech dosen't know what the problem is.......With out knowning how old your blower is, do you have a good fuel filter in the tank ? If yes, it's not the carb, do you have a air filter on the carb that is not letting dirt pass, if yes, it's not the carb.
More then likely, it's the rings sticking or maybe the seals on the crank. If you have a "few" hours on that blower, if you can check the compression when it's cold and then when it won't start. You should have a min of 90 psi
at all times. You can tell if the seals are bad by taking the recoil off and see if you have any kind of leakage and there is another one of the fan side, that one is alittle more work to get to :) The seals help the carb to breathe

MowerMedic77
07-20-2007, 10:01 PM
I would have to say if gas is pouring out of your carb(flooding) then it is a carb issue:hammerhead:

Most Sthil BR400s have a Walbro HD carb this has a large diaphragm gasket that tends to wear out and also I have seen the needle stick in the carb body. If your dealer rebuilt it(or fixed it:confused: ) and it still is not right take it back.

Or if you have some mechanical skill and you just want to replace the carb post the #'s off of the carb itself and I can tell you what to order and were to order it so you can just replace it and you will be back up and making money.

Breezmister
07-20-2007, 10:56 PM
[QUOTE=MowerMedic77;1903209]I would have to say if gas is pouring out of your carb(flooding) then it is a carb issue:hammerhead:

I would agree if the carb had a bowl and float

Most Sthil BR400s have a Walbro HD carb this has a large diaphragm gasket that tends to wear out and also I have seen the needle stick in the carb
body. If your dealer rebuilt it(or fixed it:confused: ) and it still is not right take it back.

If the diaphragm was bad, then he would not beable to start it in the first place, of course, it could be a vent problem with the tank, but I've never
seen a Stihl have that kind of problem :)

MowerMedic77
07-20-2007, 11:34 PM
[QUOTE=MowerMedic77;1903209]I would have to say if gas is pouring out of your carb(flooding) then it is a carb issue:hammerhead:

I would agree if the carb had a bowl and float

You are right no bowl or float, but the diaphragm acts as the float for 2 cycle and if the gasket is worn or stiff and making constant contact with the needle lever arm then yes the carb will flood. Handheld 2cycle work on crank case vacuum via the pulse port, you prime the carb with the primer bulb and choke it and the movement of the piston and the clearance of the piston skirt and cylinder wall create the vacuum needed to pulse the diaphragm up and down and press the needle lever open and closed.

And 90lbs of compression is borderline dead most units run crappy with that kind of compression most 2 cycle handheld should pull 110-120lbs three pulls no problem on any compression gage.

Breezmister
07-21-2007, 03:53 PM
[QUOTE=Breezmister;1903264]

You are right no bowl or float, but the diaphragm acts as the float for 2 cycle and if the gasket is worn or stiff and making constant contact with the needle lever arm then yes the carb will flood. Handheld 2cycle work on crank case vacuum via the pulse port, you prime the carb with the primer bulb and choke it and the movement of the piston and the clearance of the piston skirt and cylinder wall create the vacuum needed to pulse the diaphragm up and down and press the needle lever open and closed.

I'll get something different all the time that I've never seen before, but I don't think I've ever come across a flooded diaphragm carb, but that just means I might have missed it:confused:
Anyway, for those that didn't understand that mechobabble :dizzy: There is a little hole on the intake side of the cylinder just below the intake port. That hole passes through the insulator to the carb, if this passage is blocked
the carb won't work, and sometimes they do get blocked. What ever you do, don't put the gaskets on backwards:nono:
And, if you have gone this far to check that passage, take the insulator off and check to see if the engine side is flat, I've seen a couple of then warp from the heat. A sheet of emery paper on a hard flat suface and some elbo grease can fix this problem.

DSIM
01-08-2012, 02:20 PM
I know this is an old thread but I'm currently having the same problem now. I have 2 420's, one is two years old the other 6 and just last year they both are doing the same thing. After use the next day the air filter is full of gas and the spark plug is wet.
I have to remove and dry then they will start back and run great. This progressively got worse and worse until it got to where it is now.

There were some suggestions on here but no followup as to what the solution was.

I took the carb off of one and sprayed it with cleaner and blew it out but that didnt change anything. There must be blockage somewhere I would guess.

My frustration with these makes me want to sell and buy Redmax but I dont want to sell this problem to someone else.

ed2hess
01-08-2012, 08:04 PM
I got several and they all flood but not to the extend you describe. Yours sounds like the carb is leaking. Now that can be debris i the needle or can come from bouncing around. Also pressure builds up in the tank and I think that is a problem. We pull the rope about 5 times with the unit off before trying to start it. Then 3 times with no choke and usually they start. Seldom do we use the choke. I like these blowers but they do flood easily.

DSIM
01-08-2012, 09:36 PM
Ok thanks Ed

cpllawncare
01-11-2012, 11:15 PM
I got several and they all flood but not to the extend you describe. Yours sounds like the carb is leaking. Now that can be debris i the needle or can come from bouncing around. Also pressure builds up in the tank and I think that is a problem. We pull the rope about 5 times with the unit off before trying to start it. Then 3 times with no choke and usually they start. Seldom do we use the choke. I like these blowers but they do flood easily.

That's how I started doing mine and it works well, my new 600 will start on the first pull almost every time though.

MR-G
02-01-2012, 08:03 PM
i know this sounds like the last thing that can cause flooding....check the keyway that holds the magneto on the shaft....it can appear to be fine when you spin it...but can be slipping on the shaft under a load...causes the engine to pump in fuel and not burn it...i pulled my hair out for weeks trying to figue it out....a 3.00 keyway and has been fine since....note : if you have ever had a shirt get suck into the intake your keyway is at least damaged and will fail eventually........hope this helps

ed2hess
02-01-2012, 10:20 PM
I don't think they are slipping .....I had another one that gas was coming
out of the carb. I took the carb apart and cleaned it out with carb cleaner and the problem was stopped. I think there was debis in the float seat. I kept thinking about the tank vent but that didn't affect squat. The unit can still be flooded however.

blake101
02-10-2012, 04:26 PM
I know this is an old thread but I'm currently having the same problem now. I have 2 420's, one is two years old the other 6 and just last year they both are doing the same thing. After use the next day the air filter is full of gas and the spark plug is wet.
I have to remove and dry then they will start back and run great. This progressively got worse and worse until it got to where it is now.

There were some suggestions on here but no followup as to what the solution was.

I took the carb off of one and sprayed it with cleaner and blew it out but that didnt change anything. There must be blockage somewhere I would guess.

My frustration with these makes me want to sell and buy Redmax but I dont want to sell this problem to someone else.

Had the same thing happen here, also cleaned carb and did not fix it. Replaced carb with a new one and runs great. $40.00 BR600

Valk
02-10-2012, 06:31 PM
Had the same thing happen here, also cleaned carb and did not fix it. Replaced carb with a new one and runs great. $40.00 BR600
Not calling you out, just wanting to know if you used compressed air?

blake101
02-11-2012, 01:27 AM
At the time the only thing I had was carb cleaner in a can, I now have a air-compressor. The air-compressor would probably have done the trick. Now have a extra carb for back up if needed.