Farm boss 038av hot start

[stewie1046]

I have a very old - but great cutting saw- starts first or second time on the choke start. Cuts great. But if it stalls or a stop for re fuel- can I get it to start warm!! Never.

Have to wait 20 minutes- and start on choke.

New plug- clean filter- new fuel.

Any thoughts ideas really appreciated!

Stew

[ChrisNewport]

Does the compression feel a lot less when youre trying to start it when warm?

[spudulike]

As above, if the saw has relatively low compression, it will drop off further with running and this will cause hot start issues. 

Other than that, the fuel tank breather can be checked out as if it is semi blocked, the vacuum caused through running may cause an air lock.

Also check the carb settings/colour of the spark plug. If the saw is running lean on the L screw, it may be difficult to start when you aren't using the choke.

On an old machine, the compression is the most likely as it will have many hours use so it will be worn and may have been nipped up at some stage. 

You really need 150psi+ when cold, more would be nice.

From your description, it sounds like the engine doesn't cut out in mid cut but only when you switch it off or it just stalls when idling. If it was cutting out mid cut flat out, it could be a coil/HT issue as heat can stop the coil functioning if faulty but it could do it mid cut or as yours does - had a 460 once like that and it was the coil to flywheel gap being too large.

[stewie1046]

Many thanks- yes it’s old- but not massive use. The problem is getting worse. . Just had it serviced and it needed a new fuel line- but got a new spark plug etc.

Does not cut out when rev up. 
But if it stalls on idle - or I turn it off, even after 1 or 2 mins can’t re restart it for 10 mins - then with choke?

Any ideas on getting compression sorted?

[spudulike]

You need the top end off (including the muffler and carb), inspect the plating on the cylinder for damage and wear. It may have worn through to the aluminium if the air filter is a wire mesh one.

Place the piston rings in the bore checking the end gap. Measure up the piston especially the lower skirt.

Replace parts as necessary. 

If the cylinder is OK (hope it is), try to source a Meteor or Hyway replacement as they are pretty good replacements to OEM. Go careful on the size as there have been a number of variations of this saw.

Other than that, if the cylinder is shot, try for a secondhand OEM part or a kit from the same manufacturers as mentioned earlier.

[stewie1046]

Cheers mate. Will do. What has got me thinking is that I can’t ever remember having the issue prior to serving it. I had an issue with leaking fuel- fuel pipe worn out- but they said it had water in fuel??

Did notice that it runs rich- what I mean is that when idling the chain runs around bar- is this usual?

Hope this can help you further- but many thanks for your input so far! Where are you based as a matter of interest?

Cheers again- it’s such a powerful saw- and has served me well to date- don’t want to send it to the saw shop in heaven just yet!

[stewie1046]

Ps it has a mesh( metal) filter - which I have cleaned.

[spudulike]

Those metal mesh air filters are pretty poor and years of letting through fine dust can take its toll on the inlet side of the cylinder around the inlet port. 

The chain spinning on idle is either down to the idle speed being too high or the clutch springs being shot. The stalling of the machine may be down to the idle being run low to stop the chain spinning or the carb being incorrectly set but as I said, a high idle or bad clutch springs are the normal reason for the chain to spin....I would suspect the clutch springs are shot.

PM me with where you are but am not really doing much work now.