EVAP Canister R&R?

[highwaystar]

This EVAP canister is original with nearly 300,000 miles. No issues but should it be replaced? Source? Thanks, Robert.

 

[someotherguy]

If the truck doesn't have a history of the fuel tank being overfilled, and the plastic isn't broken on the canister, leave it.

The whole reason for the "don't top off" warnings at gas pumps is because of the evaporative emissions equipment that has been in use for decades now. If you overfill the tank, liquid fuel, instead of vapor, gets forced up the vapor line into the canister and ruins it.

Richard

 

[grampadirt]

Yup,leave it.My Burb has 274,500 miles on it and the canister looks to be the original(I've had the Burb for fifteen years).I know it's good cuz my Burb just passed SMOG check today,the only glitch was the gas cap had to be replaced...no surprise there.

 

[pgutier1]

This might be a stupid question...is this thing really necessary? Can it be deleted? Asking for a friend...LOL!

 

[DerekTheGreat]

This might be a stupid question...is this thing really necessary? Can it be deleted? Asking for a friend...LOL

Not unless you want to smell fuel when you park your vehicle. I THINK those things work by pulling the vapors from the intake into that canister when the engine isn't running. Then while the engine is running, it ingests the vapors and hence the "tsst!" you get when you spin the gas cap off to refuel. (Maybe?)

If the truck doesn't have a history of the fuel tank being overfilled, and the plastic isn't broken on the canister, leave it.

The whole reason for the "don't top off" warnings at gas pumps is because of the evaporative emissions equipment that has been in use for decades now. If you overfill the tank, liquid fuel, instead of vapor, gets forced up the vapor line into the canister and ruins it.

Richard

Hrmmmm. I'm that guy. I can get about four extra gallons in the tank if I top it off. And by "top off" I mean I'm going until I see gas standing in the filler neck, just past the little brass flappy thing. How can I tell if I've trashed my evap canister?

 

[someotherguy]

Hrmmmm. I'm that guy. I can get about four extra gallons in the tank if I top it off. And by "top off" I mean I'm going until I see gas standing in the filler neck, just past the little brass flappy thing. How can I tell if I've trashed my evap canister?

Gonna vary depending on vehicle design, and pump behavior, and who knows what other variables. I'm sure some vehicles are more susceptible to it than others.

I've seen canisters with distorted plastic, bulging and cracked open like a bad battery. Speaking in really general terms, if your canister is full of fuel then you should be experiencing fuel mixture issues and would notice.

The guys at work are constantly overfilling the wreckers (Godzilla 7.3's and a few earlier 6.8 V10's) and several of them have developed hard start issues where they crank forever and then finally fire and stumble up to an idle.. kind of like a Vortec 7.4 with leaky injectors. Not my job to maintain/repair them so I don't know for a fact it's because of the constant over-filling damaging the canisters, but if I were a betting man...

Richard

 

[someotherguy]

This might be a stupid question...is this thing really necessary? Can it be deleted? Asking for a friend...LOL!

California smog refs are forming a perimeter around your home as we type.

Not unless you want to smell fuel when you park your vehicle. I THINK those things work by pulling the vapors from the intake into that canister when the engine isn't running. Then while the engine is running, it ingests the vapors and hence the "tsst!" you get when you spin the gas cap off to refuel. (Maybe?)

Yes - the evap canister-equipped vehicles have a one-way vent on the gas cap - it should vent inside so the tank doesn't collapse under vacuum, but not vent externally when under pressure (like pre-emissions vehicles) because fuel vapor is considered a pollutant. So instead the vapor travels up that extra fuel line (the tiny one off the sender, smaller than the supply and return lines) up to the canister. The canister has a check valve in it and it feeds the vapor into the intake stream - later vehicles have solenoid-controlled valves to exert tighter control over these events. GMT400's started using a solenoid-controlled purge valve in 1994; that's the little rectangular dude sitting on the intake by the thermostat housing, with the plastic vacuum line running over to the canister.

That's my amateur-level knowledge on the matter.. someone here probably knows a whole lot more about the system and how it works.

Richard

 

[grampadirt]

This might be a stupid question...is this thing really necessary? Can it be deleted? Asking for a friend...LOL!

Yep,CARB has their eye on you.Some might not know...CARB is California Air Resources Board and they go to bed with OSHA.

 

[DerekTheGreat]

Gonna vary depending on vehicle design, and pump behavior, and who knows what other variables. I'm sure some vehicles are more susceptible to it than others.

I've seen canisters with distorted plastic, bulging and cracked open like a bad battery. Speaking in really general terms, if your canister is full of fuel then you should be experiencing fuel mixture issues and would notice.

The guys at work are constantly overfilling the wreckers (Godzilla 7.3's and a few earlier 6.8 V10's) and several of them have developed hard start issues where they crank forever and then finally fire and stumble up to an idle.. kind of like a Vortec 7.4 with leaky injectors. Not my job to maintain/repair them so I don't know for a fact it's because of the constant over-filling damaging the canisters, but if I were a betting man...

Richard

Hmmm. I look at that thing occasionally, not bulged or strange looking. Truck starts and runs as if it was new. I have been curious about that though, and do not top off the fiancée's 2002 Tahoe as I consider that a modern car which might be susceptible to my shenanigans.

How do you like those 7.3s? I remember thinking to myself Ford did something right by going back to a single camshaft and 2 valve per cylinder design.

 

[HotWheelsBurban]

The EVAP system is real sensitive on the 800s; went through changing the solenoid under the truck on the '06. Not a fun job even with the spare tire off. The "quick disconnect" is anything but.....
So I don't top any of our vehicles off anymore.