Do you happen to recall which line?? Either way there should be NO fuel in any lines lead into or out of the CC. That will saturate CC-
Did you get a CEL or recorded DTC?
Do you ever top off your fuel- or do you stop at first click?
Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?
- Thread starter 2001LC
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Do you happen to recall which line?? Either way there should be NO fuel in any lines lead into or out of the CC. That will saturate CC-
Did you get a CEL or recorded DTC?
Do you ever top off your fuel- or do you stop at first click?
Has anyone experienced a loss in power with this? That would be a sign if there is a vacuum leak or fuel sending issue.
Here is the part that was replaced at 152k on my cruiser. Dealership noted a PO441 code in their memo line. I have to imagine sometimes the computer catches this and sometimes it doesn't.
Vapor Canister Purge Solenoid. Dealership called it the "Evaporative Emissions System Vent Valve"
#9091012268
It looks like a fairly easy part to verify serviceability on. The question is, what is the trigger for the PO441 CIL code?
Vapor Canister Purge Solenoid. Dealership called it the "Evaporative Emissions System Vent Valve"
#9091012268
1999 Toyota Land Cruiser Vapor Canister Purge Solenoid. Evap - 9091012268 - Genuine Toyota Part
Vapor Canister Purge Solenoid. Evap. 1999 Toyota Land Cruiser. Genuine Toyota Part - 9091012268 (90910-12268, 9091012130)
parts.toyota.com
It looks like a fairly easy part to verify serviceability on. The question is, what is the trigger for the PO441 CIL code?
Could work but remember there are 4 fuel/vapor hoses (going & coming) that would need the wrap. I just bought some exhaust wrap that I going to try around $15 for 25ft. Plan to wrap all 4 lines that are near the cat & a little beyond.
Has anyone tried wrapping the actual exhaust pipes with exhaust wrap?
I thought about it, too expensive for the good kind. For me at least. I can only say the shield, and the way people are doing it, including me, is only a a few dollar expense and maybe an hours work, if that.
I don't think there is a better way to insulate the stock cat on the drivers side than the stock clam shell cover, And or in conjunction with the heat shield. Wrapping the piping and or hoses in the rear seems like a band aid to a different problem that was created by another problem.
My thought back then was, start at the pump (and check valve) . Then the line to the rail, then regulator, then return to tank. Seems like if you take care to fix that right there, the rest will be normal. I don't remember measuring but I assume right now the return hard line is bigger diameter than the feed line. That even makes it easier for vapor to expand. More pipe surface area, more heat soak etc.
If in fact you're pushing air right after the regulator which seems to me to be the only place where it would start happening, then the slug only gets bigger after the spring check regulator, past the cat, and then to tank, where air pressure build up happens. Then it's just overwhelming the ability of the tank until the temp curve starts downhill.
then it starts again and the cycle continues. Lot's of temp volume and pressure stuff happening in there.
I don't think there is a better way to insulate the stock cat on the drivers side than the stock clam shell cover, And or in conjunction with the heat shield. Wrapping the piping and or hoses in the rear seems like a band aid to a different problem that was created by another problem.
My thought back then was, start at the pump (and check valve) . Then the line to the rail, then regulator, then return to tank. Seems like if you take care to fix that right there, the rest will be normal. I don't remember measuring but I assume right now the return hard line is bigger diameter than the feed line. That even makes it easier for vapor to expand. More pipe surface area, more heat soak etc.
If in fact you're pushing air right after the regulator which seems to me to be the only place where it would start happening, then the slug only gets bigger after the spring check regulator, past the cat, and then to tank, where air pressure build up happens. Then it's just overwhelming the ability of the tank until the temp curve starts downhill.
then it starts again and the cycle continues. Lot's of temp volume and pressure stuff happening in there.
I found this video very informative on how the whole system works. Good info for diagnosing.
And this thread and specific post on Yota Tech explains Toyota's "intrusive" type EVAP system very well ( the best explained step by step diagnosis process I've read yet). This is related to EVAP systems where CC is located above spare tire. Also this requires scan tool or Techstream.
Basic operation Explained:
"EVAP DESCRIPTION AND OPERATION
Pressure in Tank
As the pressure in the tank builds, it will unseat the tank valve assembly, travel through the charcoal canister, and exit through the fresh air drain.
Vacuum in Tank
As pressure drops in the tank, fresh air comes through the Canister Control VSV, through the air valve, through the canister, through the vacuum check valve, and into the tank through a rollover valve.
Secondary Vacuum Release
The secondary vacuum release is the one way check valve in the gas cap.
Refueling
While refueling, high pressure in the tank forces fumes through the rollover valve, out through the On-Board Refueling Vapor Recovery Valve, through the charcoal canister, and out the fresh air valve.
Purge Mode
While purging, when the EVAP VSV is turned on, it draws air in through the Canister Closed Valve, through the air inlet valve, charcoal canister, and EVAP VSV and into the engine so the hydrocarbons stored in the canister can be burned."
P0446 code - what have you replaced to fix? - YotaTech Forums
95.5-2004 Tacomas & 96-2002 4Runners - P0446 code - what have you replaced to fix? - A few weeks ago, the check engine, VSC OFF and TRAC warning lights came on. In 8-1/2 years and 184,000 miles, I've never had a CE light come on. So I swung by Advance Auto, borrowed their reader and found that...
www.yotatech.com
Basic operation Explained:
"EVAP DESCRIPTION AND OPERATION
Pressure in Tank
As the pressure in the tank builds, it will unseat the tank valve assembly, travel through the charcoal canister, and exit through the fresh air drain.
Vacuum in Tank
As pressure drops in the tank, fresh air comes through the Canister Control VSV, through the air valve, through the canister, through the vacuum check valve, and into the tank through a rollover valve.
Secondary Vacuum Release
The secondary vacuum release is the one way check valve in the gas cap.
Refueling
While refueling, high pressure in the tank forces fumes through the rollover valve, out through the On-Board Refueling Vapor Recovery Valve, through the charcoal canister, and out the fresh air valve.
Purge Mode
While purging, when the EVAP VSV is turned on, it draws air in through the Canister Closed Valve, through the air inlet valve, charcoal canister, and EVAP VSV and into the engine so the hydrocarbons stored in the canister can be burned."
I have no experience with any the issues related to this, live at sea level. Don’t ever top off drive a 02 lx 470 with 280k
Essentially my reply has zero value, with the exception of.
I have been changing out all the rubber hoses, under the hood.
My vent line or the charcoal canister was clogged, probably has nothing do do with any of the issues.
I just found that odd,
The line goes from the front of my charcoal canister and vents into the frame rail
Essentially my reply has zero value, with the exception of.
I have been changing out all the rubber hoses, under the hood.
My vent line or the charcoal canister was clogged, probably has nothing do do with any of the issues.
I just found that odd,
The line goes from the front of my charcoal canister and vents into the frame rail
Last edited:
I have had this happen to every 100 I've ever had. The most commonalities for me:
- Medium to High Altitude. Happens a lot at over 12k feet for me, lowest ever was just over 6k feet. Never had it happen below 6k feet.
- Low humidity. Zero idea why this would play into it, but for me invariably occurs on low humidity <15% days. Temperature does not present itself as a consistent determining factor for me,
- Any higher-test fuel than 85 AKI octane. Premium fuel causes a stall condition for me; rather, I've never had this happen with lower-test fuels though sample sizes too small. The fuel smell is ever-present, regardless of octane rating.
- Laden.
Last edited:
Fuel grade and seasonal blend are contributors. Not sure if its a mountain myth (as opposed to an urban myth) apparently lower octane fuel at higher altitude helps slow this issue. But this seems counterintuitive. Since high octane is less volatile (burns slower) than low octane- and low octane is higher volatility -fuel vaporizes faster.
My only guess (cause Im not a petroleum engineer) is that lower octane fuel has less or no ethanol, and little to no additives (like higher amounts of butane, ethanol, oxygenates etc used to increase octane) which flash off faster when heated. Fwiw- Butane boils at 30F degrees.
Another thing adding confusion is that all grades have to meet federal RVP criteria-summer blend 9.0 psi and winter blend 14-15psi. With the exception of certain metro areas through out the country (Denver included) and all of Calistan that have lower mandated RVP of 7.0 ~7.8. So if all grades have same RVP- it seems reasonable that lower or higher octane would vaporize (pre-ignition) similarly; maybe not?. 10% ethanol added to fuel lowers its boiling point. I found this interesting:
The boiling point of fuel is increased in a pressurized container/ closed system. So if there are any vacuum leaks in your evap, tank, cap, and your system isnt holding pressure it will contribute to lower boiling point, more vapor/off gassing where evap cant keep up. (This is just a guess).
Summarizing fixes contributed here thus far: Eliminating vacuum leaks, mitigating heat soak, ensuring up to date cooling system and engine maintenance, running lower octane fuel at high altitude and for newer trucks with CC above spare tire, running 3/4 or less fuel in tank on the trail.
My only guess (cause Im not a petroleum engineer) is that lower octane fuel has less or no ethanol, and little to no additives (like higher amounts of butane, ethanol, oxygenates etc used to increase octane) which flash off faster when heated. Fwiw- Butane boils at 30F degrees.
Another thing adding confusion is that all grades have to meet federal RVP criteria-summer blend 9.0 psi and winter blend 14-15psi. With the exception of certain metro areas through out the country (Denver included) and all of Calistan that have lower mandated RVP of 7.0 ~7.8. So if all grades have same RVP- it seems reasonable that lower or higher octane would vaporize (pre-ignition) similarly; maybe not?. 10% ethanol added to fuel lowers its boiling point. I found this interesting:
The boiling point of fuel is increased in a pressurized container/ closed system. So if there are any vacuum leaks in your evap, tank, cap, and your system isnt holding pressure it will contribute to lower boiling point, more vapor/off gassing where evap cant keep up. (This is just a guess).
Summarizing fixes contributed here thus far: Eliminating vacuum leaks, mitigating heat soak, ensuring up to date cooling system and engine maintenance, running lower octane fuel at high altitude and for newer trucks with CC above spare tire, running 3/4 or less fuel in tank on the trail.
Last edited:
Fuel's octane rating is directly related to altitude (barometric pressure) so as you go up in altitude the fuels effective octane rating goes up also.
So I have this problem right now actually starting today and it’s really bad- 10-15 second pressure release. I also noticed my one way valve/flap is missing. I confirmed with a buddy and his has the valve on his cruiser. Could this have anything to do with it? I’m also at altitude at the moment and just replaced the gas cap from oreillys as that’s the only one readily available, but it’s still happening. Mine is the blue one, his is the white.0
Last edited:
Interesting but I dont think that flap matters. I have an 03 that I had the tank and filler neck replaced OEM at dealer and bother before and after I had no flap. My be a year think or an LC vs LX??
As seen in some of the previous posts the gas cap seems to be the secondary release point for pressure in event evap system cannot handle excess pressure in tank. Figure out cause/symptoms of the pressure build up or what is failing in your evap system that seems to be the issue.
This could be the answer. Wouldn’t allow purging of pressure and wouldn’t throw a code because valve is operating as it should. Probably mud dauber nest or something clogging these.
- Thread starter
- #97
Likely the flapper fell into filler tube neck or springs came off and it just hanging there hidden from sight. IDK, but tend to agree with @Jfoofighter16 that it likely is not your issue. But let's not rule it out totally just yet. I say this because it could plug air from escaping normally as cap removed. This may give impression of over pressurized.
If you or your buddy has and OBDII that can read temps and fuel trims, hook it up on todays drive. See what reads you can log and report back here.
If you or your buddy has and OBDII that can read temps and fuel trims, hook it up on todays drive. See what reads you can log and report back here.
What are the correct numbers for coolant temp, and fuel trims? Which fuel trims do you measure? I'd like to start collecting data to add to this conversation, just not sure what data is relevant. I have a Bluetooth OBD unit connected to Torque.
- Thread starter
- #99
Great!
I was planned on asking everyone to monitor data points. Engine coolant temp being number one data point I'd like to see.
Having just engine coolant temp from those having these issues and those not, would be valuable. As would knowing if any coolant or engine issue corrected or signs of running hot in the past or present.
Coolant Temps and Fuel Trims are number one I watch!
Coolant temp:
Coolant temp is what I'm the most interested in. 184 to 189F engine coolant temp is best case. It's what I just saw on a 6 hour test run, from elevation of 5,000 to ~8,000 ft, after corrective service to engine/coolant system. OAT ran ~75F to 95F during my drive mostly HWY with some minor off road at ~7,000 to 8,000 ft w/OAT of 75F. Worst I got was 190F briefly, in stop & go HWY gridlock, w/OAT of 95F at end of the drive 6 hr test drive. I had frt & rear AC on the entry time.
You may see a bit higher. As this was; pure stock 99, old 2 people in vehicle no added weight, old factory temp sending unit which I added BG Flush than Super Cool. The Supper Cool may have reduced system operating temps a few degrees, IDK, but claims too. Added weight, bigger tires, missing foam or aftermarket skids/bell pans can affect temps also.
One thing to watch is how fast coolant temp jumps up. Rapid change (going higher) is sign something not to spec.
Fuel trims:
I like watching both short term (ST) and long term (LT) fuel trims (FT). But feel long term is most important. Depending on whether idling, accelerating, cruising we get different numbers. But as throttle held steady; Anything close to 0% is good, over 5% is concerning. If we see LT FT running about +5%. This indicates engine running lean. LT FT is what EUC is doing to correct and smooth out short running condition. Having ST FT log helps confirm, but I feel less important.
RPM:
RPM is nice to watch. Then you can see if idling, accelatring, cruising as you go back and review logs. Add in MPH would be helpful here.
CAT temps:
CAT temps are a good one also. But I've only pulled those on 06-07.
My BlueDriver OBDII:
Since my Bluedriver OBDII recommends monitoring no more than 5 data points. I'm going to start just logging; Engine coolant temp, bk 1 & bk2 LT FT and RPM.
I've also set one group of 5 data points and driven for 1/2 my drive. Than without shutting down I'll set a different set of Data points. Than email the log before shutting down or disconnecting the Bluedriver.
Does anyone know the PIDs necessary to bring vapor pressure data into Torque?