EVAP fails on long climbs at altitude

[Tofel]

Hi guys,

Lateley I`ve been having gasoline smell in the car. It happens only on prolonged climbs (1-2h) and at heights (between 1500 and 4000 m). From what I`ve checked in FSM EVAP system sucks the vapors into the manifold only with hot engine and RPM above 3000, so my theory is that with prolonged climbs (L or 2, 2000 RPM max) the carnister gets overflowed and cannot store any more vapors. Can it be so or the capacity of the carnister should be much, much higher? Any of you had similar problem?

Should I forget about the issue and release the vapors manually (loosening the hose going to carnister or opening the fuel tank cap?), change the carnister or maybe install one more in parallel/inline with the existing one?

I`ve checked the EVAP as per FSM and the system behaves as expected (although the sucction above 3000 RPM with hot engine isn`t super strong and blowing air into the carnister requires some effort).

Any advices?

Cheers from Cordillera Central in Colombia,
Bartek

 

[nukegoat]

New canister probably

 

[Camino]

Canister, I installed a vc120 from autozone 3 years ago and it works perfect (it was cheap too).

 

[Landseer]

Toyota charcoal canister is ~$300. GM canister is about $40.
Charcoal Canister - Great Option!

 

[Wayne]

I just rebuilt mine and it works perfect. Landcruiserphil and Firsttoy have very good write ups with pic on how to rebuild the original one. It takes a little time (getting the lid off) , but it's worth it.

 

[PabloVTA]

you need the VC120, Toyota OEM are not available....(well, in the US anyways).
Just did mine last weekend. get three feet of 1/4" I.D. fuel line and change those out too.
use a zip tie to hold it in place until you have time to add a longer bolt. you don't have to add the bottom hose from the factory part...it just goes two feet into the fender well anyways. probably a great way for water to come into it during a deep crossing.

 

[Tofel]

Thanks guys!

I've read somewhere that Toyota stopped producing the one for $300 (thank the gods! ). I'll try to look for something made for GM cars from the 90's. In US it would be easy, but I've just arrived to Medellin one hour ago and here it will be a completely different story! But maybe I'll find some spare parts among armored Land Cruisers abandoned on the property of Pablo Escobar )

 

[NW Wheeler]

Tofel, With the long sustained climbs that you describe don't be surprised if you still get a little gas smell after replacing the canister. A month ago four of us (all 80s) were traveling through the Rocky mountains and all of the vehicles experienced some gas smell on the slower climbs. I have tested the Evap. system and had replaced the canister just before the trip, the gas smell was the worst on the the vehicles that had not replaced their canisters.
Rapid extreme elevation changes and warmer ambient temperatures seem to aggravate the problem. Sometimes after pulling a long grade, one can hear a boiling sound in the gas tank, if you think about the hot fuel that recirculates back to the tank is easy to understand how the heat can build up in the tank. Then when climbing and moving slowly off road, add in heat from the exhaust.
While doing the testing I found that the Evap. system does not have any vacuum applied to it until the engine exceeds 1500 RPM, so maintaining RPM over that may help. I too have wondered if some kind of manual bypass around all of the Evap. valving directly into the manifold would help.

Opening the gas cap can be scary, one of the guys in our group had done this in the past, he said it spewed fumes and raw fuel for over five minutes!

 

[atomicshawn]

^^^ NW's experience is mine as well. A new canister can made a tremendous difference, but still get gas fumes slow speeds at altitude.

...I too have wondered if some kind of manual bypass around all of the Evap. valving directly into the manifold would help...

I've pondered on this too...

...Opening the gas cap can be scary, one of the guys in our group had done this in the past, he said it spewed fumes and raw fuel for over five minutes!...

Years ago made the mistake of doing this... yea, not a good idea.