Homelite mystery issues

[Ifixoldjunk 778]

So I was using my old XL-12 on some nasty thick hardwood. The chain was razor sharp but just due to the size of the wood it was definitely giving the saw a workout.

 

maybe after the 3rd cut the gas cap vent blew out of the side of the cap and the saw began spraying a pressurized stream of gas around 5 feet into the air.

 

after leaving it to sit, I removed the gas cap and it looked like air was still bubbling from the fuel filter. 
 

is there some kind of air vent on the gas tanks on these old homelites? Is it a carburetor issue? Any ideas? I’m lost.

[Ifixoldjunk 778]

Im currently running a 20’ bar and chain on this saw, which has never been a problem in the past. According to the owners manual it should be able to handle up to a 24’

[wallfish 16,994]

I've never had any pressurize the tank. The carb works by a diaphragm sucking in fuel from the tank and the cap vent let's air in just like a tractor setup does. Maybe heat is pressurizing the tank but IDK.  The caps use a duckbill vent to allow air in and stop gas from escaping if it's tilted so it is a check valve. For a gas stream to shoot out the tank cap it must've been sideways with fuel covering the cap otherwise it would've been just air shooting out. 

Is the saw running lean and hot?

[WHX?? 48,815]

Mine have brass filter like plug to keep dirt out there but wouldn't be surprised if there was a duckbill behind it. I probaly have some of those duckbills if I can find them. i think I got five of them off the jungle for cheap or 

 

https://www.jackssmallengines.com/jacks-parts-lookup/part/homelite/560955001?gclid=cj0kcqjwkruvbhcharisacviioytdnqhbxc0dcqdkopdkjfs23gn84wanlqpjrqe7p7ghesczl9h7ssaavptealw_wcb

 

My guess is the duckbill plugged & fuel expanded in the heat of the battle and blew out. 

Edited June 19, 2022 by WHX??

[Ifixoldjunk 778]

@WHX?? mine had the brass plug and duckbill at first. The pressure in the tank sent them flying. I wonder if it was a defective duckbill with no opening?

[Ifixoldjunk 778]

@wallfish The carburetor seems to be correctly adjusted, the saw didn’t seem too hot when this happened. It seems like it builds up a little pressure every time it runs anymore. I’m gonna try a new gas cap and vent

[WHX?? 48,815]

Guy wouldn't think so ... like 'Fish said the duckbill is supposed to let air in and keep fuel in. Like a check valve. Something must have happened to let the thank get pressurized. Maybe running hot??? 

5 minutes ago, Ifixoldjunk said:

little pressure every time it runs anymore.

Maybe something funky going on in the carb? I don't remember to they have a return to tank from the carb? 

I've got three old Homelites, a smaller XL a 360 and a beast of a 550. Heavy as sin but man do they cut when running good. 

Edited June 19, 2022 by WHX??

[Ifixoldjunk 778]

@WHX?? There’s no return line. Coulda been running hot. I was definitely giving it a workout. I’m leaning more towards carb issues because it’ll build up pressure after running for even a minute or two

[WHX?? 48,815]

BTW there is a seller on fleabay who is good with older Homelites & parts

[WHX?? 48,815]

4 minutes ago, Ifixoldjunk said:

leaning more towards carb issues

Gotta be, maybe a diaphragm  but one would  think it would run crappy tho? 

[Ifixoldjunk 778]

@WHX 

I forgot to mention that last time I used it for some serious cutting it would continue to draw fuel to the carb even after shutting it off. I guess I’ll do the cap and a carb rebuild

[WHX?? 48,815]

Yep same as mine ... gotta be a carb thing then. Since I only use mine once in a great while I run the 40:1 canned fuel in it and since then my carb issues went away. The stuff has got an ungodly shelf life and doesn't rot carb diaphragms or turn to varnish.  

[wallfish 16,994]

The carbs also have check valves inside in the form of flaps that cover holes in the carb body. It works the same way a kohler vacuum fuel pump works except it's inside of the carb. The pulse for the diaphragm movement to pump fuel is created from the case vac and pressure so if it's pushing fuel into the carb after shutting down then that's from pressure in the tank causing it. I'm guessing it's running hot and excess heat along with the vibration is expanding the fuel and is creating the pressure in the tank. At atmospheric pressure, gasoline has an initial boiling point of 95 °F so it doesn't take much excess heat to reach that point. Try adjusting for more fuel. Make sure nothing is blocking the air flow from the blower housing and the head fins are clean

There's a forum called "House of Homelite". Just like here, there will be someone that has experience with your condition and should be able to provide answers. 

[wallfish 16,994]

The carbs also have check valves inside in the form of flaps that cover holes in the carb body. It works the same way a kohler vacuum fuel pump works except it's inside of the carb. The pulse for the diaphragm movement to pump fuel is created from the case vac and pressure so if it's pushing fuel into the carb after shutting down then that's from pressure in the tank causing it. I'm guessing it's running hot and excess heat along with the vibration is expanding the fuel and is creating the pressure in the tank. At atmospheric pressure, gasoline has an initial boiling point of 95 °F so it doesn't take much excess heat to reach that point. Try adjusting for more fuel. Make sure nothing is blocking the air flow from the blower housing and the head fins are clean

There's a forum called "House of Homelite". Just like here, there will be someone that has experience with your condition and should be able to provide answers. 

[Digger 66 3,478]

Normal tank pressure is from 0 > 15 PSI .

The cap seal , duck-bill valve or any other means of venting should withstand that .

I'd be checking fuel filter & lines first , then the needle valve for proper operation as well as it's ability to "seat" & seal .

Then the metering diaphragm 

[lynnmor 7,305]

I would try some fresh fuel mixture, preferably non-ethanol, and see what happens.  Ethanol will absorb moisture right out of the air and when it reaches saturation there will be liquid water in your tank.  That liquid can cause the pressure you mentioned when very hot.  Keep you gas cans and tanks closed, open only for the time it takes to fill in order to keep exposure to the humid air to a minimum.

 

I have replaced all of the duckbills behind the sintered filter in the fuel caps, they go bad over time. I have seven operating Homelites and a few more to be assembled.

[gwest_ca-(File Mod) 11,041]

Think the ethanol fuel melts the duckbill into a rubber gob.

[lynnmor 7,305]

4 hours ago, gwest_ca said:

Think the ethanol fuel melts the duckbill into a rubber gob.

 

Homelite used a black rubber duckbill and everyone I have seen was indeed a black rubber glob.  Hopefully the new red ones are tolerant of today's fuels.