Still woodboss 028 won’t run?!

[adam_h_86]

Hello - advice wanted please! I’ve been given a Stihl woodboss to use to cut up firewood etc, it’s sat in a cupboard at our workshop for 20 years?! I’ve changed all the service bits (new carb, fuel line, plug and fuel filter. It seems to start but only run for five seconds then dies and won’t restart?! Is there a something I’ve missed?! A vacuum hose or something that pulls the fuel through?! ? any help would be gladly received ?also can’t work out where this screw goes back?! Any ideas?! 

[Khriss]

I would start with a carb  strip n new fuel/ impulse pipe. New plug Obvs.  20 yrs is too long to expect it to fire up at all ! But good find n def worth the effort . K

[billpierce]

Have you tuned the carb? If its new it will need setting up. Many youtooob videos on this

[lurkalot]

Screw is perhaps part 13 here, https://www.diyspareparts.com/parts/stihl/diagrams/028/2e65f7fe-5b5d-4760-9eea/

[Stubby]

4 hours ago, Khriss said:

I would start with a carb  strip n new fuel/ impulse pipe. New plug Obvs.  20 yrs is too long to expect it to fire up at all ! But good find n def worth the effort . K

He has done that and more ...

[spudulike]

Is the compression OK? It should have between 150-170psi. If you don't have a compression gauge, pick the saw up by the starter/recoil handle and it should drop slowly with distinct holds where the piston comes to top dead centre. A full drop on the handle should take in the region of 8-20 seconds.

If this doesn't grab you, remove the muffler and look at the piston through the exhaust port and see if it looks scored.

Failing this, it may be the impulse line, split manifold, dodgy Chinese carb, etc and the screw looks like part 1121 791 6105 some sort of screw from the top AV buffer.

[Khriss]

Apologies Mr Stubby, I would add crank bearing seals to the list also, if it's suckling air thru perished seals-won't rev out. K

[bmp01]

If you are interested in how the cab works have a look at the attached Walbro info. 

Briefly: On choke setting fuel is sucked into carb and the intake port by the piston on its down stroke. During normal running, one half of the carb operates like a pump, lifting fuel from the tank into the other half of the carb - the metering side. 

Once you have fuel in the carb (and in the saw) from being on the choke setting, if you then take it off choke and the saw runs for a few seconds (while the fuel is used up), then either the carb settings are way out or the carb isn't pumping fuel from the tank. 

Walbro.pdf

Edited August 15, 2019 by bmp01

[adam_h_86]

Thanks for all the advice! This is the service kit I bought -

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F332944691969

 

is that a Chinese  carb?! Are they a load of rubbish, haven’t done anything to the new carb just bolted it in and would the two screws out a turn and a quarter, I look Further into it! 

[billpierce]

Thanks for all the advice! This is the service kit I bought -
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F332944691969
 
is that a Chinese  carb?! Are they a load of rubbish, haven’t done anything to the new carb just bolted it in and would the two screws out a turn and a quarter, I look Further into it! 

Have a go at tuning that carb. Turn and a quarter on each should get it to run, check the idle screw as this could need some turns in