View Full Version : Learned something new today

07-16-2010, 04:17 PM
On the BOWR, Matt Farr mentioned his 80 had the same gas smell near the drivers side tire. Mine has been doing that for a while.

So I did some research on Mud and found out I have been doing something wrong. I fill both tanks to the brim. That causes the Charcoal Canister to saturate with vapor.

That causes three things, impact to fuel economy, high pressure in the tank and the gas smell

I have noticed when I take the gas cap off, there is high pressure, sometimes even sputtering fuel.

This can also cause fuel to boil if the heat gets hot and there is a high Ethanol blend. I had abnormally poor fuel economy coming back from Kansas a couple of weeks ago. It was about 7MPG and I wasn't even towing. Back in Colorado, it returned to about 12 MPG with a fresh tank of fuel.

These new through our discount are about $250. Kind of high considering its a can with some Charcoal in it.

On mud Firstoy has a write-up how he cut the top off and replaced the Charcoal using JB weld to seal the top back on.

Dan suggested I get a used one to try (Called Oleg) or I could take it off and see if sitting on my porch and being opened (via unconnected tubes) it would get the fuel to evaporate out of the Charcoal.

So the lesson is to not overfill the tank and I have been doing that for years.

07-16-2010, 04:44 PM
Interesting. I seem to remember an old thread on Mud about a guy who refilled his with charcoal from a fish aquarium.

07-16-2010, 05:32 PM
I also think there is a "cleaning" procedure in the FSM for the canister as well.
Basically running low pressure compressed air through it.

07-16-2010, 07:57 PM
I noticed it, too, on the run Wednesday. I had a full tank as well!

07-16-2010, 09:12 PM
When I overfill the Chili (5VZ-FE evap system, but with a 22RE canister) I can almost be certain I will set a code.

Shark Bait
07-17-2010, 01:46 AM
I was asking about that a meeting or two ago. Smells foul near the fuel door. Hmm. :rolleyes:

07-17-2010, 09:02 AM
I was asking about that a meeting or two ago. Smells foul near the fuel door. Hmm. :rolleyes:

That is more than likely the fuiel cap. This smell is about the front drivers side tire

07-17-2010, 03:45 PM
Saturated charcoal can be regenerated (de-saturated if you will) by applying a vacuum to it for a period of time. In the factory setup, fuel vapor goes in, then gets pulled back out via vacuum.

In a garage setting, this could be accomplished with one of our popular small electric compressors that has intake and exhaust ports. Instead of leaving the inlet open, connect it to the (otherwise sealed) canister and leave the outlet open.

I have done this with charcoal many times in laboratories. Works on most anything that has saturated the charcoal as long as the substance has a reasonably high vapor pressure. Obviously the outlet will need good ventilation to avoid excess accumulation of flammable vapors: connect a tube to it and route to a safe, well ventilated area, like outdoors.

07-18-2010, 12:08 AM
Drove to the Yota yard and bought a used Charcoal Canister for $30. When I got home, the fuel smell was worse then its ever been and poping the hood I could hear noise coming out of the canister as well

Blew the replacement one out per the FSM at 43 psi and put it in. Filled up the truck, but did not overfill. We will see how it goes.

List on these is about $320 and $250 with discount from our sources