Stihl 441. Dies when working flat out

[Ford Forester]

Hi,

Just wondering if anyone else had had same problems with Stihl 441 or knows what mine could be. Basically, the saw starts fine, but as soon as it's put under full load; ie felling, the engine dies and has to be revved back up or it cuts out completely. Always starts again straight away. My hunch is that it's dirt in. The fuel line as it only happens at full throttle and not at idle speed and sometimes sounds as if I'm about to run out of fuel when the engine races for a second or two.

 

Could it be as simple as just replacing fuel filter (never had to replace one before) or something further in?

[agg221]

The symptoms you describe are indicative that you're running lean. This means you've either got too much air or too little fuel. Lack of fuel could be down to dirty filter, blocked tank breather or carb blockage. Excess air would be down to an air leak somewhere - could be crankcase, crank seals, carb boot, carb, fuel line or impulse line.

 

Changing the filter would help if it's a blockage but the most straightforward thing to do is to get it pressure and vacuum tested. This will confirm whether you have any leaks. Running with leaks is a really bad idea as it can lead to a lean seize.

 

If you don't know anyone extremely local to you, Spudulike on this forum is near Baldock and is very good at this sort of thing.

 

Alec

[KGBFINGAR]

Sounds like an airleak to me .

[spudulike]

Lack of running when hot may be a number of things - fuel related issues a possibility as Alec has said.

 

Compression is also a candidate - as a saw gets hot, the compression drops and can make a hot saw difficult to start if not impossible - you would also suffer a bit of bogging - it is worth popping off the muffler and looking at the piston through the exhaust port - any vertical scoring to the piston and it may be toast.

 

Air leak - possible but generally will cause idleing issues and the revs won't drop back to idle after a high speed run as symptoms - a total seizure is possible if the air leak is bad enough.

 

It may just be your carb needs adjustment if some little monkey has been busy with a screw driver:001_rolleyes:

 

The 441 has a strato engine so the carb is a bit complex compared to many - it may just need a good clean in a US bath - I have seen the seal on the welch plug break down and then enter the jets intermittently causing issues!

 

Food for thought - let us know how you get on.

[naturarbo]

dirt would be my guess,i do have a 441 :thumbup:and thats 1 of the CHAINSAWS :001_smile:with cappital letters.

most likely after a good clean by someone competent will bring it back to normal:001_smile: