550xp woes

[adw]

Mk1 or mk2 ? I have seen a fair amount of flywheel side oil seals on the mk2, and 560 mk2, when plugged into cst you need to look at and understand the jet settings, more so than the fault codes.

[spudulike]

As ADW says, those fault codes are for people without lack of imagination and are generally pretty misleading and the Jet codes are what the AT unit works out the machine needs and it is this info that anyone with half a brain diagnoses. If they are running lean - expect a blocked air filter, rich may be a blocked gauze strainer or bad pump diaphragm or air leak.

If you are checking yourself, check the gauze strainer and the pump diaphragm pump flaps. The strainer may be full of fine wood chip or the pump flaps may be perforated on impact with the holes they block.

[openspaceman]

1 hour ago, spudulike said:

If they are running lean - expect a blocked air filter, rich may be a blocked gauze strainer or bad pump diaphragm or air leak.

I think you should edit that reply @spudulike

[adw]

I didn’t like to mention it.

[spudulike]

23 minutes ago, openspaceman said:

I think you should edit that reply @spudulike

Why?? If the air filter is blocked, the AT will LEAN the mix as the blocked filter is over fueling, if the gauze strainer is blocked or the pump diaphragm is shagged, the AT will richen the mixture due to the system not delivering enough fuel!!!

If you look at the AT jet settings....you would come to the same conclusion....wouldn't you???

[spudulike]

10 minutes ago, adw said:

I didn’t like to mention it.

That's because I am right!!!

[adw]

Sorry misunderstood, you were talking about the jet settings, should not have doubted you.

[openspaceman]

12 hours ago, adw said:

Sorry misunderstood, you were talking about the jet settings, should not have doubted you.

Yes me too, not having played with AT carbed saws I didn't realise the implication as it was opposite to which an old fashioned carb would be.

[spudulike]

So...if the air filter is blocked, any saw will run rich as you are shutting off air and putting more of a pull on the carb  high speed check valve as you do on a half or full choke setting.

On the AT saw, it recognizes that the engine is over fuelling so it leans down the amount of fuel going to the engine. If you look at the AT jet figures you can clearly see that the H jet will be running lean to compensate for the blocked air filter.

That is the point I was making after ADW mentioned that the AT fault codes are a bit iffy and the thing to look at is the H&L jet figures on the AT print out.

If a non AT saw had a blocked air filter and you did a Tach tune, you would lean down the saw in the same way but you would then cock the setting up when you cleaned the air filter.

The AT unit will richen the fuel if an air leak is present.....those jet figures are about the only interesting thing on the print out TBH!