Carbon Canister and evap. system on Gas RTV?

[kmelander]

Can I delete this system and simply vent the fuel tank like normal, simple lawn tractors do? Do other SxS's use fuel evap. systems? It truly seems overly complex for this little ~450cc engine and 5 gal fuel tank. Seems like a good idea since I don't know much about them, other than 95% of the vehicles I've owned have had some sort of problem with, and triggered an CEL, due to the evap. systems.

That little "check valve" seems sketchy.

 

[lugbolt]

people have removed them but the downside is that wherever you store the machine, you WILL have fuel fumes building up. That's what the canister does, it uses activated charcoal to absorb the fumes instead of venting the fumes to atmosphere. EPA stuff so removing it is tampering with emissions devices which may not be legal. It doesn't hurt anything to leave it.

lawn mowers use them, SxS's use them, cars have used them since, gosh, early 1980's?? A LONG time. Possibly 1970's. People take them off all the time then they gripe about gas fumes. Well duh.

 

[wendol]

Not a RTV, but same dilemma on a Scag Zero Turn. I didn't realize it had a set of charcoal canisters until after the purchase, and then to learn the down side of having them.........i.e. being careful to not over fill the tank, using a hoist to raise the mower to clean the deck, mowing slopes, etc. could create problems with gas in the canisters.

After more research I found that Ferris (using the same identical engine) did not use the canisters, therefore I removed mine. Engine runs great, with no noticeable fumes when stored in the shop.
FWIW.....just my experience.

 

[fried1765]

Not a RTV, but same dilemma on a Scag Zero Turn. I didn't realize it had a set of charcoal canisters until after the purchase, and then to learn the down side of having them.........i.e. being careful to not over fill the tank, using a hoist to raise the mower to clean the deck, mowing slopes, etc. could create problems with gas in the canisters.

After more research I found that Ferris (using the same identical engine) did not use the canisters, therefore I removed mine. Engine runs great, with no noticeable fumes when stored in the shop.
FWIW.....just my experience.

I don't think that my zero turn, SCAG Liberty Z (21HP Kawasaki) has any canisters.

 

[kmelander]

people have removed them but the downside is that wherever you store the machine, you WILL have fuel fumes building up. That's what the canister does, it uses activated charcoal to absorb the fumes instead of venting the fumes to atmosphere. EPA stuff so removing it is tampering with emissions devices which may not be legal. It doesn't hurt anything to leave it.

lawn mowers use them, SxS's use them, cars have used them since, gosh, early 1980's?? A LONG time. Possibly 1970's. People take them off all the time then they gripe about gas fumes. Well duh.

It's just too many components and too complex for the application, IMO. It could conceivably cause issues if it malfunctions. A vacuum leak? In fact, once the weather cools off a bit, I'll be doing some testing to see if capping off that vac source from the TB has any effect on how the machine is running.

 

[lugbolt]

It's just too many components and too complex for the application, IMO. It could conceivably cause issues if it malfunctions. A vacuum leak? In fact, once the weather cools off a bit, I'll be doing some testing to see if capping off that vac source from the TB has any effect on how the machine is running.

on a lot of cars the ecu compensates for the slightly "richer" mixture when the purge valve is opened. I can't speak for mowers, I do not know their ecu strategies, although I would assume it would be similar.

 

[kmelander]

on a lot of cars the ecu compensates for the slightly "richer" mixture when the purge valve is opened. I can't speak for mowers, I do not know their ecu strategies, although I would assume it would be similar.

good point. in fact, I've been researching aftermarket ECU possibilities, just to know whats out there and learn more about the topic. Have you ever heard of Speeduino? I never knew it existed and it looks very interesting...and cheap. I spent thousands on a Holley Terminator system for my project car. Speeduino looks like it can be done for about $150 plus the sensors. I think, based on my research so far, there would be some challenges on this little Subaru engine. Primarily the TPS, or lack of one currently, and possibly the crank sensor. Sure would be nice to have a window into what the hell this troubled little engine is experiencing. Maybe I'll get lucky and find this evap system is the culprit. At least I have a couple more things to check before I'm completely vexed. If it winds up being the crank sensor, I'll explore the Speeduino solution more seriously in an effort to avoid removing the engine to replace the oem sensor. Id have to replace the throttle body with one that has a TPS and figure out a crank sensor solution. Something custom on the accessory drive side of the engine I imagine. Hopefully it doesn't come to that, but I'm prepared to go that far if necessary to fix this little bastard.