Could I have a bad or failing evap canister?

[EvilMole]

I've posted before about my rough low idle and declining gas mileage, but now I'm noticing a raw gas smell in the cabin while driving. I've had it die on me once while pulling into a parking spot. I believe these can all be symptoms of a bad evap canister, but I have no check engine light on. The usual suspects have either been replaced (plugs, wires, O2 sensors) or cleaned multiple times (MAF, IAC).

This is a '96 model that has the burping canister issue that was never addressed. Don't know if that has anything to do with it or not. I'm kind of drawing at straws here. My original thought was a vacuum leak but I'm not dismissing the evap canister.

Thanks.

 

[BamaDrewski]

I've posted before about my rough low idle and declining gas mileage, but now I'm noticing a raw gas smell in the cabin while driving. I've had it die on me once while pulling into a parking spot. I believe these can all be symptoms of a bad evap canister, but I have no check engine light on. The usual suspects have either been replaced (plugs, wires, O2 sensors) or cleaned multiple times (MAF, IAC).

This is a '96 model that has the burping canister issue that was never addressed. Don't know if that has anything to do with it or not. I'm kind of drawing at straws here. My original thought was a vacuum leak but I'm not dismissing the evap canister.

Thanks.

Generally, the smell of gas fumes does indicate a bad canister or perhaps a leaking injector. With your rig being 22 years old, it could be a myriad of things. The canister has a "vacuum switching valve" that can fail. When it does, you notice more gas fumes. I have had the issue on my 2000 T4R and by installing another vacuum switching valve, it solved it.

One other possibility is the fuel pressure regulator. (They are pricey and would recommend you pull one from a pull yard)

I have a couple of canisters if you need one...

 

[MStudt]

Sounds more like a purge valve issue to me. The raw gas can be the rubber gasket around the purge valve on your gas tank. Often times when your carbon canister goes out that rubber gasket isn't far behind. Or, at least that was my case.

I replaced the carbon canister, and then the rubber gasket started leaked. The vehicle would die after filling, and occasionally when driving when it was getting low on gas. Each time we'd fill up the fumes were pretty bad too.

 

[T4topher]

There is a way to test the evap canisters, it’s somewhere in the FSM. You need a small hand operated Vacuum pump though I think.

 

[Toyotayoda]

yes, and it's not terribly complicated. So you will need a vacuum gauge, a section of hose and a "T". You "T" the hose between the purge valve and the canister( if you have the little green "T" from the factory you don't need to do this, just remove the valve from that, it's left threaded) and then attach the vacuum gauge to that "T". Next you are going to warm up the engine, at 175-180 the vacuum gauge should start to bounce, this is normal, it means your purge valve is operating. Once you have determined that the purge valve works you will need to operate the Canister close valve(CCV), if you don't have a scanner to do it, you can ground it, if you aren't comfortable with electronics just pinch the hose going to it. with the CCV closed the bouncing vacuum gauge should begin to pull vacuum ( do not do this with fuel level over 85%, do not allow vacuum to drop below 29in/hg.) If there is no vacuum created there is a leak, and not necessarily a large leak, a cracked hose will cause this. Lets Assume you do get vacuum, and you bring it to about 27in/hg, you would then unplug the purge valve to seal the system. The vacuum will leak gradually, the fact that it's ably to pull at all is a win, you just want to hold for a couple minutes to make sure it doesn't rise sharply, nor should the vacuum continue to drop. Of course this sort of test is only to verify the system can function, it won't tell you if you have a restriction in the canister, or a stuck overfill valve, but it makes it easier to narrow down what your problem actually is. All that being said I would definitely look into fuel injector issues and fuel pressure, vacuum leaks tend to go in the opposite direction of your symptoms(high idle and lean codes). no codes doesn't mean no problems, fuel trim would be necessary to have an idea what is going on in your case.

 

[TrustG]

Generally, the smell of gas fumes does indicate a bad canister or perhaps a leaking injector. With your rig being 22 years old, it could be a myriad of things. The canister has a "vacuum switching valve" that can fail. When it does, you notice more gas fumes. I have had the issue on my 2000 T4R and by installing another vacuum switching valve, it solved it.

One other possibility is the fuel pressure regulator. (They are pricey and would recommend you pull one from a pull yard)

I have a couple of canisters if you need one...

Any way I could get one of those canisters? My car is stalling every time I put it in and gear and think this might help.

 

[EvilMole]

Don't drive this truck much so this issue was not addressed until recently (10 months from original post). Don't judge me, I'm slow.

Finally had the check engine light come on a month or two back and it threw a P0441 code. The truck was stalling a lot more when sitting at a light or just idling thru a turn. So I bit the bullet and bought a new Toyota canister. I'm happy to announce that I believe my issue is now solved. Not only is it not stalling anymore but my idle appears to be smoother and as an added benefit I no longer have that annoying burping/buzzing sound the '96 was known for. Don't know yet if this will help my gas mileage. I'll know after the next fill up.

 

[Dubz25_]

Generally, the smell of gas fumes does indicate a bad canister or perhaps a leaking injector. With your rig being 22 years old, it could be a myriad of things. The canister has a "vacuum switching valve" that can fail. When it does, you notice more gas fumes. I have had the issue on my 2000 T4R and by installing another vacuum switching valve, it solved it.

One other possibility is the fuel pressure regulator. (They are pricey and would recommend you pull one from a pull yard)

I have a couple of canisters if you need one...

Long shot here but any chance you still have a canister?