Serious Gas Tank Pressure!

[SiRaDuDe]

After a long UPHILL MUD mountain ride, over 4 hours of mud climbing and HOT weather.

Most of the ride on fully locked and at extreme up hill angles..

Well after finishing the ride and coming down to a gas station (maybe 15-20 minutes after done climbing) I opened my gas cap and WOOOOOOOOOSSSSHHHHHHHH, a large release of gas, and it was HOT, it all lasted over 2 minutes!!! before I could even start to put gas in!

I started the mountain with a full tank of gas, by the time I reached the mountain I had 1/2 tank left.... I also recently had changed the gas cap. (and also recently did a head job).

I know this is not normal under regular driving condition, but I have not tested if it also occurs on daily driving... will test late..

So my question is... Is this normal, when driving on such steep angles? and WHY was the gas so HOT!

What should be my steps to diagnose if not normal!

Thanks!

 

[bryson]

Time to replace the charcoal canister. Do a quick search and you'll find all the info you could ever want.

 

[Kernal]

Here's a previous thread:

https://forum.ih8mud.com/80-series-tech/292965-excessive-fuel-tank-pressure.html

 

[Paul_L]

https://forum.ih8mud.com/80-series-tech/412261-charcoal-canister-great-option.html

 

[Josh N]

Interesting, at least the 4th thread I have seen on this same thing in teh past few days. Everyone's charcoal is crapping out it seems.

 

[e9999]

good news is your gas cap is in great shape!

 

[SiRaDuDe]

Thanks for the replies!

That #4 thread was long and had a lot of good info!

I will check my CC. but bet that very high ambient temps at high RPM and low speed mixed with HIGH angle steeps up and down mixed with a full tank could also had my CC over saturated and worked..

Engine bay temps were VERY HIGH, so was my fuel temp (felt from exiting gas pressure)

Meanwhile I think I found a local autozone with the suggested replacement.


THANKS!

 

[Overland Tailor]

Just as an aside I replaced mine when I had pressure on a daily basis and the canister resolved the problem.

Unfortunately I had a similar wheeling experience as yours after the new canister and after several hours was smelling fuel. I released the gas cap and let it vent for a few minutes and did not experience it again.

In talking to Beno seems that once the canister reaches "Full" so to speak it will vent to the outside and you will smell fuel even with a new canister. He stated that he tends to vent the tank every few hours at the gas cap when wheeling like this.

Again, the canister fixed the daily pressure problem, but high temp, slow wheeling might still result in pressure and fuel smell.

Good luck -

John~

 

[akarilo]

Had the same issue this past weekend. I bypassed the CC and all sysmptoms disappeared. I may just leave it that way.

 

[scottryana]

Mine is bypassed and staying that way.....

 

[flow]

can we discuss the rationale behind bypassing the canister now?

advantages vs drawbacks? Emissions compliant?

 

[ironhippy]

bypassing is just running the vent tube directly to the intake instead of through the canister?

I am currently venting mine through an inline fuel filter to atmosphere, but like the idea of running it back to the intake..

 

[gtfour43]

Mine is bypassed and staying that way.....

Can you post a pic of what you did?

Notice any changes since doing the bypass?

 

[scottryana]

I can post pics but basically all I did was take the charcoal canister out. Take the line from the gas tank and use a longer piece of hose and extend it to the in frame vent, and then capped off the vacuum line from under the manifold. Took basically 10 min.

I haven't noticed any changes, except no longer having presure build up in the tank. When I was in Colorado last year, I took my gas cap off at 13,000ft and it spewed gas and vapor for 3-5 min. That is no longer a concern.

 

[ironhippy]

That's nearly the same as what I did but instead I'm just venting through a fuel filter (right beside where my diff breathers terminate)

 

[86tuning]

can we discuss the rationale behind bypassing the canister now?

advantages vs drawbacks? Emissions compliant?

Certainly not emissions compliant.

Proper fix is to replace canister if its faulty.

Field fix when wheeling hard is to manually vent it if the canister is working properly.

 

[bigfj62]

How much is too much. I have some vapors that come out for about three seconds when I open my gas cap. So what is normal?

 

[240 Jordy]

I have the same problems at higher evaluations during hot weather . . . . . . Subscribing to read later.

Thanks everyone!

 

[Camino]

Canister.

 

[landtoy80]

If you vent to atmosphere wont that cause a fire hazard from the fumes?
Wont you still smell the fumes?

If you vent directly to vacuum port wont that cause negative pressure in gas tank?