Mysterious problem Stihl 038 AVS

[spudulike]

Glad it turned out OK in the end but still not sure of the route cause - could it be crap in that gauze filter?

 

Anyway, sounds like it is all good now:thumbup:

[GardenKit]

Now we know it was defo the carb, so my theory is that the metering valve arm was a little too low.

 

When the fuel pump was lifting fuel into the metering chamber it was at a pressure where the metering diaphragm could overcome it easily and open the metering valve.

 

But when the pressure in the metering chamber was increased a little by the 'head' of petrol when the saw was on the side, the atmospheric pressure acting on the diaphragm could not push quite far enough to open the valve.

 

Well, thats my theory anyway.

 

Glad its working for you now Charles.

[spudulike]

Now we know it was defo the carb, so my theory is that the metering valve arm was a little too low.

 

When the fuel pump was lifting fuel into the metering chamber it was at a pressure where the metering diaphragm could overcome it easily and open the metering valve.

 

But when the pressure in the metering chamber was increased a little by the 'head' of petrol when the saw was on the side, the atmospheric pressure acting on the diaphragm could not push quite far enough to open the valve.

 

Well, thats my theory anyway.

 

Glad its working for you now Charles.

 

Very possible - my two were crap in the gauze filter or possible that the needle valve plating had lifted making it difficult to open when on its side - had an 020AV like that!

[Charles Ekin]

Rich2484

The last round of repairs/replacements that I did involved getting new "o" rings. I noticed they were missing the last time I took the carb apart and cross-referenced it with the exploded view parts diagram I had. Didn't make a blind bit of difference. That was the last thing I could think of and when that failed, I turned to the forum.

Spud

Whenever I took the carb apart there was never any crap in that little gauze.

Gardenkit

Bloody hell, you know your stuff! That's really casting pearls before swine! Is the metering valve arm what they call the inlet control lever on the parts diagram?

Again, many thanks to all.

Charlie

[GardenKit]

Rich2484]

Is the metering valve arm what they call the inlet control lever on the parts diagram?

Again, many thanks to all.

Charlie

 

Yes, thats the thing. I tend to use my own terminology as all manufacturers use slightly different names. Sorry to confuse!

[Al Smith]

You kind of lost me with reference to a gasket until I looked at the parts list .In a few references it does show a gasket .Now keep in mind the the 038 av could have any one of 4 or 5 different carbs .

 

I've had a lot of these saws apart and never ran into one with a gasket .They had a sleeve which went on the inside of the boot and a washer type retainer on the outside .The carb seated right up to the boot ,no gasket .

 

Glad whatever it was you got it worked out .Those are pretty good saws all things considered