066 Dies when hot (Air leak?)

[back of beyond]

All:

My favorite saw has an annoying problem. Runs like a raped Ape till About 1/2 tank in, saw starts to sound like its starving for fuel, acts exactly like a saw does when you run out of gas, air leak suspected but cannot locate.

This is a flat top, non de-comp saw. It does have a timesert in the spark plug hole. Aluminum flywheel, 1311 coil.

Saw has 165 PSI compression. It holds a vacuum for 10 minutes at 80kpa. ( I do not have a pressure gauge)

The carb was replaced with new Stihl/Walbro carb. Coil has been swapped with known good coil. New seals, intake, impulse. New tank vent, fuel line and filter, OEM parts. Cylinder is OEM and piston is OEM.

Any suggestions before I get mad enough to sell this for parts? (hate to do it!)

 

[blacksmith]

I am no master but you said that the spark plug has a threadsert in the spark plug hole. Did you try giving the spark plug and extra tighten after it starts acting up or try to snug the base bolts for the cylinder?

Sounds like you corrected everything else that could be wrong. Or you may have a small crack in the case that may open up once it gets hot enough. Just spit balling here.

 

[Moparmyway]

All:

My favorite saw has an annoying problem. Runs like a raped Ape till About 1/2 tank in, saw starts to sound like its starving for fuel, acts exactly like a saw does when you run out of gas, air leak suspected but cannot locate.

This is a flat top, non de-comp saw. It does have a timesert in the spark plug hole. Aluminum flywheel, 1311 coil.

Saw has 165 PSI compression. It holds a vacuum for 10 minutes at 80kpa. ( I do not have a pressure gauge)

The carb was replaced with new Stihl/Walbro carb. Coil has been swapped with known good coil. New seals, intake, impulse. New tank vent, fuel line and filter, OEM parts. Cylinder is OEM and piston is OEM.

Any suggestions before I get mad enough to sell this for parts? (hate to do it!)

Next time this happens, open the fuel cap for a second, does it spray out a gulp of air or suck in a gulp, put the cap back on and see if the problem is gone. Wont take you but 5 seconds to do after you use your 1/2 of a tank

 

[HYPERSAWS]

Sound like electrical to me

 

[Junk Meister]

Does it die regardless of the position of saw when you are cutting? Are you working it fairly good when it dies ? I don't have a 066 but am wondering if fuel line might be collapsing when fuel is low due to the weight of filter and strange circumstances Like post #2 I am merely spit-balling a thought. My 056 Mag saws are temperamental like post #3 suggests and even when cap vent seems to be working if the diaphragm is weak I get this starving for fuel die out .

 

[back of beyond]

Position of saw doesn't seem to affect it... dies whenever it gets hot.

 

[back of beyond]

New theory, give me your input boys...

I had a snow day from work today, I just went and bucked a cord of wood with it. I ran saw from 1/2 tank to empty, refilled and finished the rest of the cutting. Saw ran great. Idle great. No problems, no stall, no nothing.

I started thinking. I have that saw tuned for my house/shop which is 4000 ft elevation. Where I'm cutting at currently is 2800-3000 ft. I've heard folks always say elevation plays with your carb adjustment. I've only used the saw at 2800-3000ft with the stall problem. Is it possible the saw is leaned out at the lower elevation due to the elevation change and thats causing the stall problem?

Its all I have for explaining why that thing dies religiously at that lower elevation after 1/4-1/2 tank of gas after seeing the saw run great today at 4000 ft.

Any input?

 

[Moparmyway]

New theory, give me your input boys...

I had a snow day from work today, I just went and bucked a cord of wood with it. I ran saw from 1/2 tank to empty, refilled and finished the rest of the cutting. Saw ran great. Idle great. No problems, no stall, no nothing.

I started thinking. I have that saw tuned for my house/shop which is 4000 ft elevation. Where I'm cutting at currently is 2800-3000 ft. I've heard folks always say elevation plays with your carb adjustment. I've only used the saw at 2800-3000ft with the stall problem. Is it possible the saw is leaned out at the lower elevation due to the elevation change and thats causing the stall problem?

Its all I have for explaining why that thing dies religiously at that lower elevation after 1/4-1/2 tank of gas after seeing the saw run great today at 4000 ft.

Any input?

Next time this happens, open the fuel cap for a second, does it spray out a gulp of air or suck in a gulp, put the cap back on and see if the problem is gone. Wont take you but 5 seconds to do after you use your 1/2 of a tank

 

[back of beyond]

Sucks air in. I've tried that several times and still no restart until the saw cools down. New tank vent and hoses anyway....

I'm leaning toward this carb tuning thing. I'm going to try to adjust it richer at the landing next time I'm down low and see if it stays running

 

[Moparmyway]

Sucks air in. I've tried that several times and still no restart until the saw cools down. New tank vent and hoses anyway....

If its sucking in air, your tank vent has a problem

I'd wager that youre going to have to give a bunch pulls on choke after you close that cap, will get her to fire, remember, she just ran the hose and carb outta fuel

 

[back of beyond]

Cancel that, I typed wrong, its blowing air OUT.