Stihl 038AV Magnum - choke problem

[TimSim]

Hi. I am new to the forum although have followed it over the past year or so whilst I have used small chainsaws. I recently bought a Stihl 038AV Magnum for some larger work. It works well but is difficult to start. I know from this forum that they have a reputation for being difficult but this can take 50 or 60 pulls (when I can manage it).

 

When cleaning the air filter I noticed that the Choke Shutter it contains does not appear to be operated by the 'cam' on the rhs of the Switch Shaft when the choke position is selected. When the shaft is in the choke position the cam is at least a mm from the 'peg' of the choke shutter.

 

My first reaction was that the filter or shaft must be out of position but this is not the case. They are both too precisely fixed. The part numbers on the air filter seem to correspond to those given in an old service manual for 028/038 saws which I bought on the net. So it doesn't look as if the wrong part has been fitted by an earlier owner.

 

I have no idea how this can be fixed so any suggestions would be really appreciated.

 

Thanks

[GardenKit]

I had one like that recently and the choke shutter was misplaced within the air filter. Split the air filter, refitted the shutter correctly ( and the return spring) and all was well

[spudulike]

Pretty much as Barrie says - the choke needs to be fully sealed to get the first shot of fuel vapour in to the engine which is why you are pulling 50 - 60 times to get it working:blushing:

 

Sort the choke out first. The other thing I have had in the past is that the fast idle starting position, doesn't open the throttle valve enough, this can make starting a PITA!

 

Easy to see if you have this by getting the saw running and making sure the saw revs up to mid revs when on the fast idle position - if it doesn't then you can make up for any wear by bending the throttle linkage a little:thumbup: Just make sure that the linkage is loose in normal idle position!

[TimSim]

Thanks to you both for the quick reply.

 

I have taken another look at the choke shutter but it looks fine to me.

 

I attach (I hope) two photos. One of choke shutter as is. The other of the switch shaft. The cam which operates the shutter can just be seen. Does this cam look OK? It seems in original condition to me. I ask the question becasue it occurred to me that a part of it may have been broken off in its past life.

 

Thanks for the help.

[Rich2484]

Wounder if that's the right filter for the saw?

[spudulike]

To the parts list - http://www.keepandshare.com/doc/2062264/038-pl-pdf-july-12-2010-4-47-pm-446k?da=y it looks correct.

 

The lever should open the choke in normal running. All you can do is to push the pictured base of the air filter in to place on the two carb mounting screws and make sure the choke is held fully closed in the cold start position and then it should open in the fast idle and normal running position.

 

Check this out first!

Edited May 24, 2013 by spudulike

[spudulike]

Take a break from my earlier post - the lever on the starting lever should force the choke flap in to the base of the airfilter closest to the carb and seal the carb back on cold start.

 

If it isn't doing this then it could be the issue.

 

Another issue is as I stated earlier - the throttle valve not being held open enough to let the engine burst in to life - I have seen this on an 038 Magnum before!

[GardenKit]

Take a break from my earlier post - the lever on the starting lever should force the choke flap in to the base of the airfilter closest to the carb and seal the carb back on cold start.

 

If it isn't doing this then it could be the issue.

 

Another issue is as I stated earlier - the throttle valve not being held open enough to let the engine burst in to life - I have seen this on an 038 Magnum before!

hahah, beat me to it Steve.

Yes, normally held open by spring, but moved forward by lever to close.

[TimSim]

I think the filter may well be wrong. As I have said the cam on the shaft and the peg on the choke shutter do not meet when choke is selected.

 

I have removed the choke shutter to read the part nr, it is Stihl 1119/0 1. This does not conform to the usual numbering format but that may not be important. More importantly it differs from the value given in the parts list which I downloaded a day or so ago (and provided in another post in this thread. Thanks). This is 1119 129 2100.

 

The nrs for the mesh filters are 1119 120 1600 (carb side), 1119 120 1605 (user end). This last is correct but the carb side nr should (it seems) be 1603. However, both parts fit together well so should I simply try to get the 'correct' choke shutter? Unfortunately I cannot find a picture of the choke shutter (2100) which is good enough to show the length of the peg. It is quite cheap so it could well be worth the punt.

[GardenKit]

yours seems to be an early saw without the compensator (bit of hose joining carb to filter body, and moulded into the HL rubber cover.)

 

If this is so it should be pre ser no 144381327.

 

the carb side part should be 1119 120 1600 for metal mesh type and 1605 for handle side. 1603 is for the later type, but I think the choke part is the same anyway.

 

shutter is 1119 121 2900 and switch shaft is 1118 182 0900