Just cut my original can open! Drilled out the BB and need to get some charcoal. I've been running the VC120 for the past couple of years with no issues but would like the original can back in there. Thanks for the tech in this article!
I put an end to my Charcoal Canister problems for good! (7 Viewers)
- Thread starter LandCruiserPhil
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Well. @LandCruiserPhil was right. Tested it out on the exact same trip. 3K elev. increase, 100+deg F. Pulled into fuel station away from the pump attendant and untwisted my cap. Nothing. Not a sound. No vacuum. Also, I opted not to change out the carbon. No smell, nothing. Well done, sir.
Is there any risk of the gas tank ingesting water if this mod is done and then the truck fords, say, a stream? With the vent at the bottom of the can and the check valve removed it seems like there would be nothing to stop water from sloshing into the vant line. But, maybe I'm over thinking this. Sorry if this has been mentioned already.
Good question. I forded a river 4 times that weekend deeper than the frame where the tube is housed. I surmised the venting is so gradual at this point, I didn’t worry. I have had no problem as of yet. The 2 hour drive home didn’t seem to reveal any problems.
Did the charcoal canister exactly like @LandCruiserPhil described in the first post. Had to go to the local auto parts store to use their bench grinder. This morning filled up the tank. . .and no hiss. . Blew my mind 
I'm gonna have to do something along these lines soon. I'd love to get rid of the hiss when I open the gas cap, I just don't want to create an opening that will allow water into my fuel tank. I've had the 80 in water over the hood before and I'm sure that will happen again at some point.
I think before I did it, I read a few post up that someone did everything except drilling out the ball bearing. Might want to try that.
From my understanding, while your engine is running the vent tube out the bottom of the canister is venting out with a positive pressure so I kinda doubt that you'd have water ingestion through that vent. Now if your engine stalled during a deep ford for a significant time or you parked in a lake.......it's likely to happen.
One of the main things done in this mod is elimination of the check valve, the other is changing the charcoal. I'm pretty much convinced if you cut open your canister and don't drill out the check valve, you'll be tearing into that canister again wishing you'd done it the 1st time.
I had a ton of pressure at the gas cap. As @rc51kid pointed out, there are actually two check valves, one to let the tank vent out pressure and another to let the tank stuck air in when there is vacuum. The one in the middle of the tube, which is covered by a little fabric filter that I removed, is what lets the tank vent out:
I tried really hard to clean both valves but wasn't satisfied with the result. It felt like the one in the middle could easily get plugged again so I drilled them out. Thanks @LandCruiserPhil for the idea.
I tried really hard to clean both valves but wasn't satisfied with the result. It felt like the one in the middle could easily get plugged again so I drilled them out. Thanks @LandCruiserPhil for the idea.
So I don't think drilling out the check valves is the "end-all" solution when the gasoline in your tank is hot/boiling. I drilled out both check values but still got pressure buildup and lots of fuel smell. My rig is running a little hot in engine temp, so that + ethanol + elevation change probably contributed to the gasoline boiling, which was more pressure than the engine could suck in and more pressure than the canister could purge to the outside, still leading to buildup. It also really stunk of fuel.
Just to clarify because you didn't mention it, have you tried replacing the fuel cap with a fresh OEM as well?
Yes I have a brand new OEM fuel cap.
- Thread starter
- #113
Check to make sure the line from the canister back to the tank is clear. In the summer you can still get fuel smell because one if when you modded you didnt replace the charcoal two because with the bottom of the canister being vented and the vapor are too much.
The line from the tank is not plugged and I did replace the charcoal. Even if the gasoline doesn't boil, it can still have a significant vapor pressure when it gets hot. Also, the vapor pressure increases (and the boiling point decreases) when you go up in elevation. I think excessive heat is the root issue at least in my case.
Last edited:
With my 24 gal LRA aux tank, I'm finding that with the additional pressure that current mixtures of ethynol produce in my fuel system it is necessry to leave my fuel cap loose when ambient air temps are above approx 85 degrees F. I've concluded that the additional pressure exceeds the capacity of the existing charcoal canister. So until the temp drops with Fall coming on, I'll be leaving my fuel cap loose. The aux tank is vented to the fuel filler assembly, but doesn't have a separate hose to the charcoal canister like the main tank does. Even if it did, I think it would still be too much pressure for the stock system to handle running ethynol.
- Joined
- Sep 3, 2019
- Threads
- 15
- Messages
- 208
- Location
- Lafayette, Colorado
- Website
- www.alpine-overland.com
I just finished installing an OEM sub tank system and am noticing the same thing. I'm pretty sure my charcoal canister is on its way out, but I'm hoping its sufficient after I mod it. I'm venting to my ARB diff breather manifold right now...
Honestly I would recommend against this mod, I get a terrible fuel smell when it is hot outside and regret drilling out the BBs. I'm planning to add some check valves back on the end of the vent hose to prevent the nasty smell. Many people here run the VC120 cannister which doesn't have any vent hose on the bottom, so positive pressure venting can't be that important?
The VC120 is definitely vented, but it's vented out of the bottom portion of the canister housing itself - no vent hose like OEM.
The Toyota gas cap reads, [paraphrased] "Careful when opening! There be pressure inside!" So I'm guessing some amount of offgass when the cap is initially cracked open, brand new, from the dealership, in 1993, was expected and intended.
That said, after my first alarming experience with boiling fuel 2yrs ago (lasted more than 5 minutes @8500ft one warm afternoon) I cleaned the vintage canister check valves with Oil eater and q-tips. Have had no issues since, and never had any fuel smell for whatever reason. YMMV of course. And I'll chalk this fix up to dumb luck with a canister in better shape than expected.
But I'm still curious if now having no back pressure when I crack the cap means the fuel tank is open to atmosphere somewhere. And if so, that has to effect fuel mileage if the fumes can just escape to open air. But then I have no smell either, so...again,
That said, after my first alarming experience with boiling fuel 2yrs ago (lasted more than 5 minutes @8500ft one warm afternoon) I cleaned the vintage canister check valves with Oil eater and q-tips. Have had no issues since, and never had any fuel smell for whatever reason. YMMV of course. And I'll chalk this fix up to dumb luck with a canister in better shape than expected.
But I'm still curious if now having no back pressure when I crack the cap means the fuel tank is open to atmosphere somewhere. And if so, that has to effect fuel mileage if the fumes can just escape to open air. But then I have no smell either, so...again,
