Echo fuel boiling or pressurizing?

[FlyingDutchman]

Echo CS-280e little echo top handle

Been having trouble getting the saw started when hot. When it was below freezing I could just crack the fuel cap quick and it would come to life after a few pulls. Now that it's warmer the gas explodes out and empties a quarter of the tank like it's carbonated.

Not familiar with this issue.

 

[Ronaldo]

Tank vent not venting?

Sent from my SM-S320VL using Tapatalk

 

[Hoggwood]

Sounds like the cap is functioning and tank is venting (inwards) like it should or pressure wouldn't build up. The added tank pressure is beneficial when running in warm weather to keep the fuel from boiling. I know on Homeltes, a leaking duckbill can cause fuel to boil at much lower temps. Vapour lock and/or other symptoms can follow.

You still running winter blended fuel?

 

[67L36Driver]

Sounds like tank pressure is overpowering the carb fuel inlet lever and flooding in warm weather.

Try lowering the lever a tiny amount and/or replace the needle.

Clean the inlet screen wile you have it apart.

 

[redunshee]

I'd say your saw isn't venting. Venting either thru the cap or elsewhere, lets air out of the tank. Try doing a vacuum test on the tank. If it holds vacuum, then your not venting properly. Fuel tank should hold pressure but not vacuum.

 

[rd35]

I would also take that saw apart and use an air hose to blow all the dirt out of the cooling fins and passages and the inlet hole/louvers on the starter cover. It may be getting too hot due to lack of air flow and causing the fuel tank to get too hot. The hotter the tank ....the higher the tank pressure will be. And as 67L36Driver pointed out...this excess pressure can overcome your spring load on the inlet needle and flood the cylinder with gas. Having to loosen the cap in the winter is a different issue...sort of the opposite problem. Your tank vent may be clogged and not letting air into the tank. So when it cooled off in the winter after a hard run (with excess heat due to the lack of air flow possibly), it would form a vacuum as it cooled down (which a properly working tank vent will prevent from happening) and prevent the fuel pump from being able to pump fuel through the inlet needle. By cracking open the cap, you relieved the vacuum and it would start. Two completely different problems that may both be rooted in a problem with overheating!!!

 

[lone wolf]

Echo CS-280e little echo top handle

Been having trouble getting the saw started when hot. When it was below freezing I could just crack the fuel cap quick and it would come to life after a few pulls. Now that it's warmer the gas explodes out and empties a quarter of the tank like it's carbonated.

Not familiar with this issue.

Are you using crappy pump gas? If so it could be winter gas it happens about every spring. If it is try some good gas from a can and see if it changes.

 

[lone wolf]

https://www.popularmechanics.com/ca...blend-gasoline-whats-the-difference-13747431/

 

[rd35]

https://www.popularmechanics.com/ca...blend-gasoline-whats-the-difference-13747431/

Learned s0mething new today! Thanks lone wolf for posting that link. I did not realize they added butane to gasoline in the winter when the fuel is colder. Disappointing but good to know! And, yes I now see why winter gas would build more pressure in a fuel tank. Good post!

 

[lone wolf]

Learned s0mething new today! Thanks lone wolf for posting that link. I did not realize they added butane to gasoline in the winter when the fuel is colder. Disappointing but good to know! And, yes I now see why winter gas would build more pressure in a fuel tank. Good post!

Just keep your eyes away from the fuel tank when you open it on a real hot day if you have that crap! It will volcano !

 

[FlyingDutchman]

This is definitely crappy pump winter gas, for sure. Been trying to use it up. The rest will go in the less finicky saws for sure that gobble fuel anyways. Or the car...

I think being under a vacuum makes things boil at a lower temp as well, will definitely be looking for a vent in there.

Will look at case and fins to see if plugged.

 

[FlyingDutchman]

It was pretty plugged! I'm still having issues with running and tank pressurizing, but I only had 1/3 tank of old fuel to burn. Heading for the station soon for some fresh fuel.

 

[internet disgusted]

Echo CS-280e little echo top handle

Been having trouble getting the saw started when hot. When it was below freezing I could just crack the fuel cap quick and it would come to life after a few pulls. Now that it's warmer the gas explodes out and empties a quarter of the tank like it's carbonated.

Not familiar with this issue.

 

[lone wolf]

Get canned gas, that stuff you are using is vapor locking.

 

[Chucksta]

Wow.. All along, I thought that a 2 stroke gas cap didn't vent. I've had saws boil "Winter gas" in the tank, when pushed hard on the first warm day of Spring. I thought that the reason why they didn't vent was so that they didn't piddle fuel when run upside down, or were hung up in the shed, cap down.
So... Where would any excess pressure vent out from? I've never has one dribble fuel from anywhere, even with overheated Winter gas. Does it vary from brand to brand?

 

[huskihl]

Wow.. All along, I thought that a 2 stroke gas cap didn't vent. I've had saws boil "Winter gas" in the tank, when pushed hard on the first warm day of Spring. I thought that the reason why they didn't vent was so that they didn't piddle fuel when run upside down, or were hung up in the shed, cap down.
So... Where would any excess pressure vent out from? I've never has one dribble fuel from anywhere, even with overheated Winter gas. Does it vary from brand to brand?

I don’t know of any vented caps in current production chainsaws.
The tanks are expected to contain the pressure and not vent it out.

Building pressure in the tank isn’t needed for the engine to run properly but it does help with fuel boiling and the resulting vapor lock

 

[Chucksta]

I don’t know of any vented caps in current production chainsaws.
The tanks are expected to contain the pressure and not vent it out.

Building pressure in the tank isn’t needed for the engine to run properly but it does help with fuel boiling and the resulting vapor lock

Cool.. Thanks..