Gas smell, tank pressure, aux tank issues...

[DesertRun]

Sorry, this is a continuation of a different thread where I went off topic. The link to that thread is https://forum.ih8mud.com/100-series-cruisers/350108-2005-lc-aux-fuel-tank-options-2.html#post5330912

Background: I had an aux tank (Man A Fre. Part # LR24100RAX) installed on my 2000 100. My initial and primary problem has been fuel tank pressure build up and noises (thunk/pop) coming from the tank. When I inquired about others with same tank pressure issue, spressomon pointed out that it could be a bad gas cap, or even charcoal cannister issues. One time when climbing from 1,000 ft to 10,000+ ft in 90 minutes I noticed a smell of gas coming from under the hood. It freaked me out but after listening carefully I noticed a slight hiss from a small plastic cap that was venting gas vapor under the hood. I figured it was the quick altitude change but now think the aux tank and charcoal cannister could be contributing.

I am going to replace the gas cap next week when I return home, but want to know if this issue has been tackled by anyone? Has anyone had to replace the charcoal filter due to these issues?

I know I may have two separate issues. 1) Thunking noise from tank 2) Gas smell and/or charcoal filter issues but need advice if anyone can help.

BTW, I have a SMOG test coming up in 3 months so this could get interesting since I was already worried about the aux tank and the dual fuel filler tub that has had the flap/restrictor removed. Oh well, the truck gets me places others just see in calendars...

 

[spressomon]

The gas cap seal is apart of the Toyota 90K list. However if your tank(s) is not venting the cap must be working. The cap is designed not to vent on post 70's era vehicles AFAIK.

 

[spressomon]

It would be good if one of the moderators could move the related posts to this thread.

Same experience as you described regarding the acrid smell and hissing. Of note: This issue started post aux tank install. I think replacing the charcoal should help or eliminate the issue. I'll let you know after I get mine done...or visa versa

 

[DesertRun]

The gas cap seal is apart of the Toyota 90K list. However if your tank(s) is not venting the cap must be working. The cap is designed not to vent on post 70's era vehicles AFAIK.

I will definitely be changing the gas cap, but my suspicion is that it is doing it's job. The pressure when I release the cap is always the same and is similiar to other cars I own. I have never had gas spill out nor have i had any lights come on.

 

[DesertRun]

It would be good if one of the moderators could move the related posts to this thread.

Same experience as you described regarding the acrid smell and hissing. Of note: This issue started post aux tank install. I think replacing the charcoal should help or eliminate the issue. I'll let you know after I get mine done...or visa versa

I am doing research on the charcoal canister now and will let you know.

 

[RedEuro]

Wouldnt a bad gas cap trigger the check engine light to come on for an emissions fault?

 

[DesertRun]

Seems like there are a few good threads here on charcoal cannister issues. It does not appear to be a major issue for anyone but it could be the source of one of my issues. As for the clunking noise/tank pressure issue I hope the simple gas cap will cure that. Will report back.

 

[DesertRun]

Wouldnt a bad gas cap trigger the check engine light to come on for an emissions fault?

Looks like I missed your question on emissions faults. I would think you are right, but I have never had any warning lights or bad codes. That is part of the mystery. My original issue that brought this up was the noise and clunking from the pressure, but as I researched I realized the time I smelled fuel could be related to overwhelming the charcoal cannister due to the size of the aux tank. Maybe i should ignore all of it and just get used to the occaisonal noises and manually release the pressure as others do in high heat or high altitudes.

 

[i4c4lo]

DesertRun,

I have experienced that noise in a different aux tank in an 80 Series. When it is hot out and it has a lot of vapor it will make the tank flex a little bit and will make that noise. Maybe a better venting system.

I have a different issue, same tank as hoser in a 1999 100 Series. When its hot out or at altitude AND off-road my charcoal canister can't keep up to a point that gas will spill out when I open the gas cap.

I copied and pasted this from the other thread - I am not sure if you saw it.

 

[DesertRun]

DesertRun,

I have experienced that noise in a different aux tank in an 80 Series. When it is hot out and it has a lot of vapor it will make the tank flex a little bit and will make that noise. Maybe a better venting system.

I have a different issue, same tank as hoser in a 1999 100 Series. When its hot out or at altitude AND off-road my charcoal canister can't keep up to a point that gas will spill out when I open the gas cap.

I copied and pasted this from the other thread - I am not sure if you saw it.

I appreciate it. Since I was tipped off that the charcoal cannister could be overwhelmed i searched with that keyword and found your thread and others that were very helpful. I have been in hot and high conditions and "knock of wood" have not had gas spill out, but i will be careful in the future. The first order of business is a new cap. One other question for you about the noise...did you notice a difference between aux tank full versus empty? or oem tank full versus empty? I keep my aux tank empty at all times expect when heading out on a long run, then I pump into the OEM tank mainly to the move the weight forward.

 

[NMuzj100]

With the aux tank you have greatly increased the vapor generating load without increasing the ability of the evaporative emissions control system to handle it. The 100's evap system is not too large and already taxed when going rapidly from "Low and cold" to "high and hot".

Better than replacing the charcoal canister would be installing a second one in parallel. A junk yard model out of something cheap would probably do the trick.

If it's venting under the hood then your cap is fine.

 

[DesertRun]

I think you are right, the cap and entire system are probably working great, it is just not designed for 50 gallons of capacity. There are 80 threads describing this issue in great detail since they are running aux tanks more than we are.

 

[1loudLX]

and so jerry cans finally have a positive!

 

[DesertRun]

I think i may convert my tank to water. I would use it more often and the showers will be long and hot, versus the once a year I need the extra fuel. Also those jerry cans that are collecting dust can finally get some use.

 

[rusty_tlc]

I think you are right, the cap and entire system are probably working great, it is just not designed for 50 gallons of capacity. There are 80 threads describing this issue in great detail since they are running aux tanks more than we are.

Do you think they installed a different vapor collections system in N American trucks?

I ask because there is the factory sub tank option that was offered outside the US. So one would assume that the vapor collection system would be able to handle that load.


Unless the N American trucks get a different system to meet our emissions requirements.

 

[DesertRun]

Do you think they installed a different vapor collections system in N American trucks?

I ask because there is the factory sub tank option that was offered outside the US. So one would assume that the vapor collection system would be able to handle that load.


Unless the N American trucks get a different system to meet our emissions requirements.

Not sure if the non US system is different or not. My issue has been limited to hot temp and big altitude changes so it could be just a freak problem, BUT i have a 24 gallon aux tank and I think the OEM sub tank was on 13? That could make a difference. Good question though because if the spec a different charcoal system i could order it. Let me know if you hear and I will do the same.

 

[spressomon]

Dan, If you communicate with Dave Stedman again have him get you the part # for the charcoal canister for the non-USA LC with aux tank. It would be interesting to know if they are different...which I suspect they are.

 

[hoser]

From looking at the parts catalog, the australian and middle eastern 100's have the same part number for their charcoal canister... but it is different from the US 100's. It is also $250 cheaper than the US model.

 

[rusty_tlc]

Dan, If you communicate with Dave Stedman again have him get you the part # for the charcoal canister for the non-USA LC with aux tank. It would be interesting to know if they are different...which I suspect they are.

I don't think I can afford to contact Dave again anytime soon.

 

[PabloCruise]

From looking at the parts catalog, the australian and middle eastern 100's have the same part number for their charcoal canister... but it is different from the US 100's. It is also $250 cheaper than the US model.

Hitting the search this AM, and reviving the oldies. Did you ever get a part number on that can?