It happened to me, gas venting issue

[Jeeper]

Someone squirted carb cleaner(or something) down the line from the CC towards the tank. IIRC, his theory was that there is a check valve somewhere along the line that gets clogged/blocked, leading to the excess pressure. Clean the line and valve, no pressure build up.

Makes sense, if there was no check valve, gas would flood the CC everytime we went down a steep hill with a full tank....maybe....anyways. He cleaned the line and said it fixed the prob. Haven't heard the long term prognosis. Who were you and did it solve the prob?

Yep that was me. There is some type of valve at the top of the fuel tank. Forcing carb cleaner down the "tank" line at the CC with air pressure did help. But after about 3 tank fills, I'm back to the pressure build up in the tank. Mine is not as bad as some describe on here, but more than I would expect.

So check your venting system:

-As landtank mentioned, first check the CC by the FSM method. There are check valves in the CC that can become stuck. (I have an extra CC for sale that I bought before I realized mine was good)

- If the CC looks good, then you may have blokage in the "tank" line that goes from the fuel tank to the CC. I pushed a little compressed air into the tank via this line and then could easily tell that this line was restricting flow once I allowed it to vent pressure feely. The correct fix would be to drop the tank, replace the valve on top, and replace the "tank" hose completely. But I'm going to keep trying to clean it in-place because I'm lazy.

Good luck!

 

[Atticus]

In another long thread on this topic, several people replaced their canisters and the problem continued IIRC

What about the lines going to the canister?

 

[FirstToy]

The CC is very simple. 2 valves at the top (from gas tank/to purge valve) and one vent tube at the bottom.
The bottom tube sucks in air and this may lead to the filter disk getting clogged and not allowing the CC to naturally move vapor through. There is no check valve at the bottom, just open.

The lines to the CC could be cracked but simple enough to replace rubber vac hose.

I have a thread with diagrams in 80 tech.

 

[SBFJ60FIG]

Let's get something straight here boys....when we all say "boiling" it's meant metaphorically. There seems to be some confusion and hyperbole with this word choice.

What we all have is clearly some venting issues with our tanks.

 

[RavenTai]

Actually, that is exactly what is happening. Quoting Wiki "At atmospheric pressure, the boiling point of gasoline is between 100 and 400 oF.

There are various formulations of fuel for various area's and time of year mandated by the EPA, one of the major specifications of this fuel is its vapor pressure, If some one is selling fuel with a boiling point of 100 degrees Fahrenheit in Arizona during the summer they are breaking the law.

I would imagine you might find a very low boiling point like that in winter fuel in a place like Alaska

 

[Brian894X4]

There are various formulations of fuel for various area's and time of year mandated by the EPA, one of the major specifications of this fuel is its vapor pressure, If some one is selling fuel with a boiling point of 100 degrees Fahrenheit in Arizona during the summer they are breaking the law.

I would imagine you might find a very low boiling point like that in winter fuel in a place like Alaska

I would have to agree that there has to be more to it than just the type the fuel sold, because everyone who bought that gas would be experiencing problems, and it would probably make the local news. The problem seems to be limited to our Land Cruisers. Even searching the internet, this problem doesn't seem to be very common in many vehicles. There's a few threads where similiar situations seem to have happen with motorcycle gas tanks on rare occasions, but not much else.

However, poor quality fuel might be a contributing factor combined with a venting system that is already having issues or is getting overwhelmed and might explain why it's an intermittent issue for some.

 

[Ihasfip]

I know my issue has nothing to do with elevation, or winter/summer blends of fuel so it leads me to believe its either a.) s***ty gas, b.) a clogged vent of some sort, c.) heat issues or, d.) a combination of all of the above. The only time mine has occured has been during or shorty after offroading at a slow speed in near 100 degree weather.

D

 

[NKP Garage]

What about installing something like:
Moroso 65125 - Moroso Super Cool Cans - Overview - SummitRacing.com


Anyone try this?

I think that is for carb'd vehicles running lower fuel pressure. But there are other similar items that are meant for use in high pressure fuel injected setups like ours.

 

[Brian894X4]

This write up helped me understand the EVAP system a little better....

Automotive Evaporative Emissions Systems

I looked over the FSM and I still haven't done the basic tests, but will soon. My rig is a '95 but has the OBD II components. It would seem that our OBD II 1FZs don't have fuel pressure tank sensors like other OBD II vehicles do and thus we don't get the check engine light when the gas cap is left off or has gone bad, like most other modern vehicles.

I'm pretty sure I replaced my gas cap, but I'm starting to wonder what affects a bad gas cap would have on this problem. The gas cap has a seal and a vacuum valve. It's supposed to prevent air/fumes from escaping, while at the same time, allowing air to enter the tank as fuel is used to prevent excess vacuum.

Shot in the dark theory...if the vacuum valve were stuck open (and I assume this is a one way valve) air could enter the tank, thus theoretically lowering pressure in the tank, which could lower the boiling point, which could allow the gas to more easily heat up and boil off gasses, given certain conditions, such as a combination of cheap bad gas, lower ambient pressure, higher ambient tempature, engine tempature, etc. These gasses might be overwhelming the EVAP system, which is only designed electronically release vapor at certain times, usually based on 02 sensor readings, apparently, as opposed to the actual pressure in the tank. At least our vehicles don't appear to have any tank sensors at all, so apparnetly there is no way to actually release built up tank pressure, from boiled off gas that happens abnormally. If that's correct, seems like a bit of a design flaw to me.

If the gas cap seal is working properly, which it obviously is, or we wouldn't be getting the huge whoosh when we release the cap, the pressures are contained in the tank, until it is either eventually vented off slowly and intermittently through the EVAP system, or bypasses the gas cap or leaks fumes (when we smell gas) or the gas cap is let loose.

Obviously the EVAP system is not normally constantly releasing pressure, or we would never get a whoosh when we release the gas cap when filling. The system is always under some kind pressure, so it's a matter of the system not properly releasing the pressure or something causing the pressure to rise above what it normally expects under normal conditions and it can't compensate for it.

 

[landtank]

on a trip down south we had a member's engine running hot and he "boiled" off about 5 gallons of fuel. We found the problem by hearing a buzzing sound coming from the charcoal canister. Once the truck cooled down and he kept it cool it was fine.

Are you guys running the temp mod or have some other way to ensure the engine's temps are under control?

 

[nuclearlemon]

This morning, I popped the gas cap before leaving for work. The temp in my garage was 80F. -No fumes/pressure with about 1/4 tank of gas. At lunch when I go back out, I'm sure if I pop the gas cap again, it will release fumes. I park in an underground garage, but the temps will be the same as outside. Should be around 105 here today.

in the morning, the fuel may be colder dependant on how cold it got during the night. by afternoon, it's had hours to warm up.

 

[nuclearlemon]

I think that is for carb'd vehicles running lower fuel pressure. But there are other similar items that are meant for use in high pressure fuel injected setups like ours.

they actually work great on fuel injection. a friend runs that in his fuel injected v8j40

 

[Brian894X4]

on a trip down south we had a member's engine running hot and he "boiled" off about 5 gallons of fuel. We found the problem by hearing a buzzing sound coming from the charcoal canister. Once the truck cooled down and he kept it cool it was fine.

Are you guys running the temp mod or have some other way to ensure the engine's temps are under control?

On my scangauge engine temp was well within normal range. In the 180s as I recall. It had been idling for a long time, when it happened, so I don't know what roled that might have played to help heat the fuel up if that was the issue.

 

[Ihasfip]

Are you guys running the temp mod or have some other way to ensure the engine's temps are under control?

I am not running it. I am planning on installing a manual gauge very soon as I don't trust a little gauge with no numbers. Especially one that is known for it inaccuracy. But I can say the day mine did it, it was very hot and I was going very slow. Just a few minutes before ,after and even during the time the cap was hissing and spewing fuel it was running rough, sputtering coughing and struggling to stay running. It eventually died. The temp guage had reached no higher that the 3/4 mark. Which I know have learned is VERY hot. So my problem could have all been related to that. The only thing that puzzles me is even on the drive home at 70 mph with plenty of air flow through the radiator it still ran like crap and ended up stalling out. Sat for a few minutes (opened cap and it hissed again. ALOT) and it started right up and ran fine for a few more miles. Then it stalled again. Sat for a few moments started up and drove the remaining 25 miles home without issue. Has not done it since. But I haven't been wheeling again. I also have since installed a 12" electric pusher fan. Plans to install a 10" on the tranny cooler are in the works.

D

 

[NKP Garage]

The people having the boiling issues, have you checked your fuel filters? Also, check the fuel return hose from the FPR.

There are many factors that could contribute to boiling fuel, just need to check things one by one. And if in the end everything is working fine, you may simply need a fuel cooler. There are lots of options for fuel coolers that would work just fine on our vehicles since we have so much room to mount them.

 

[Brian894X4]

It's funny you mention fuel filters, because that's the one thing MOST of us haven't replaced. For one thing it's a HUGE PITA and another, supposedly Toyota doesn't recommend it be changed...ever. I'm not making that up. Although the dealer(s) that keep telling me that, may be.

Supposedly, it's rare for it ever get plugged up on our North American gas. Supposedly.

 

[landtank]

I am not running it. I am planning on installing a manual gauge very soon as I don't trust a little gauge with no numbers. Especially one that is known for it inaccuracy. But I can say the day mine did it, it was very hot and I was going very slow. Just a few minutes before ,after and even during the time the cap was hissing and spewing fuel it was running rough, sputtering coughing and struggling to stay running. It eventually died. The temp guage had reached no higher that the 3/4 mark. Which I know have learned is VERY hot. So my problem could have all been related to that. The only thing that puzzles me is even on the drive home at 70 mph with plenty of air flow through the radiator it still ran like crap and ended up stalling out. Sat for a few minutes (opened cap and it hissed again. ALOT) and it started right up and ran fine for a few more miles. Then it stalled again. Sat for a few moments started up and drove the remaining 25 miles home without issue. Has not done it since. But I haven't been wheeling again. I also have since installed a 12" electric pusher fan. Plans to install a 10" on the tranny cooler are in the works.

D

if you were 3/4s on a stock gauge you were VERY hot. I'd check the fan clutch and radiator on that truck. You were about as hot as the guy on our trip who was having all kinds of issues.

 

[Ihasfip]

if you were 3/4s on a stock gauge you were VERY hot. I'd check the fan clutch and radiator on that truck. You were about as hot as the guy on our trip who was having all kinds of issues.

Rick, I have checked both. The clutch still feels like it is in good shape and doesn't run above the halfway mark with normal driving. The radiator appears to be very clean. I drained it and replaced the very clean antifreeze with new antifreeze but I couldn't tell a difference. I'll dump some water wetter in it and put on about 11 more fans and I should be good to go.

D

 

[NKP Garage]

It's funny you mention fuel filters, because that's the one thing MOST of us haven't replaced. For one thing it's a HUGE PITA and another, supposedly Toyota doesn't recommend it be changed...ever. I'm not making that up. Although the dealer(s) that keep telling me that, may be.

Supposedly, it's rare for it ever get plugged up on our North American gas. Supposedly.

I've seen cars (even Toyota's) that had fuel filters so clogged up they wouldn't even start. Fuel filters and sock filters need to be changed on every vehicle.

 

[Ebag333]

The clutch still feels like it is in good shape and doesn't run above the halfway mark with normal driving.

What do you mean by this?

Have you tried seeing if the fan will spin freely immediately after driving it for a while (so it's hot), or seen if you can stop the fan while it's running (with a welding glove)?