Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? (6 Viewers)

[silver02accord]

With covid slowing all auto, ship and airline jet fuel demand. Refiners drop to ~60% of capacity (normal in spring/early summer is 94 to 97%). Interesting too, they've been re-refining jet fuel into gasoline, to reduce glut of jet fuel. With so many business including gas station hurt by shutt downs and slow downs. It very likely, some less than honorable, added addition ethanal and even water, to boost profits.

The amount of water in @CUBuffs fuel pump was very strange. He drives regularly and buys from newer gas stations (newer the storage tanks, less chance of groundwater) for the most part. Speaking with BG with regards to their fuel drier product. He said; They've not been selling much Fuel Drier these days, since ethanol was mandated.




This could be the return tube. Perhaps your serpresor/anti-siphon boot fell off and sound is louder.
View attachment 2407651

View attachment 2407652

I just replaced my fuel pump on an 06 lx with denso pump and I took a picture of the entire assembly. I am not seeing this red boot on my assembly and I was very careful when removing the assembly. I'll open tank back up to check for it, but I did have the fuel boil issue this weekend after replacing the fuel pump the day before this trip.

 

[Eyedaho]

I just replaced my fuel pump on an 06 lx with denso pump and I took a picture of the entire assembly. I am not seeing this red boot on my assembly and I was very careful when removing the assembly. I'll open tank back up to check for it, but I did have the fuel boil issue this weekend after replacing the fuel pump the day before this trip.View attachment 2429177

By red boot, do you mean the thing in the lower right corner? If so, that's the pre filter. You'll want one of those. My Denso came with one, but I think you can order either just the pump, or the kit with the pre filter, tubing, etc. If you didn't get one,I think you can order one for a few bucks and put it on when it shows up.

 

[silver02accord]

By red boot, do you mean the thing in the lower right corner? If so, that's the pre filter. You'll want one of those. My Denso came with one, but I think you can order either just the pump, or the kit with the pre filter, tubing, etc. If you didn't get one,I think you can order one for a few bucks and put it on when it shows up.

I have that filter sock on there. Is what I meant is in the above pic from 2001LC he has a red boot(not yellow red) which fell back into the tank or something. He circled it in the picture( i see pic did not come through from his post) Not trying to hijack thread, just thought it may be related and noticed when reading through:

These are his pics:

 

[bluesquirrel]

I'm reporting back to say that all my fuel boiling and excessive pressure problems have been completely resolved. I am ECSTATIC!

This is what I replaced in the previous month and STILL experienced problems:

• Radiator (Spectra)
• Radiator Cap (OEM)
• Thermostat (OEM)
• Coolant Flush (Toyota Red)
• Clutch Fan (Aisin)
• Fuel Pressure Regulator (OEM)
• Fuel Pump (Denso)
• Fuel Cap (OEM)
• VSV

This is what I did differently this trip and has seemed to completely FIXED the problem:

• Extend Heatshield (I also have aftermarket CATs and used 24 gauge 24"x 4" sheet of aluminum)
• Wrap Fuel lines (used fuel wrap and galvanized steel wire)
• Fixed the pinched vapor fuel line (might have blocked venting to my CC)

Some anecdotal evidence: Came back from a 3 day trip on slow crawls and highway driving (both of which I have previously experienced these problems) in 90-105F weather, A/C blasting at 8500' in Lassen National Forest. This trip was much higher elevation, hotter, and fully loaded compared to my previous trips. My 2002 LX470 @ 196k miles has Dissent F/R bumpers, dual swing outs, full Dissent aluminum skids, 12k winch, 3 Jerry Cans, 33s on stock 16s, stock gearing, Front runner roof rack, Tepui tent, KISS drawers and sliders. The truck was also fully loaded with 3 adults so definitely very heavy. I also filled with CA 91 Octane gas (10% Ethonal) only and had a full tank to eliminate all variables. I checked fuel door every hour or so on-trail and off-trail and there was no evidence of vapor leaking or excessive pressure at all when opening the cap or fuel smell. My engine temp also ranged from 184-215F. I did hear groaning from my Charcoal Canister at 8000', but other than that I would say that my problem solved. If I were to do everything again, the first thing that I would advise addressing first are the fuel lines and making sure that they are all in order. All cooling related stuff is just regular maintenance IMHO, and I would not say that it helped solve my problem. Wrap/protect those lines!!!!

Fixed this line:
View attachment 2428804
Wrapped the lines and installed a heatshield:

View attachment 2428806
View attachment 2428810

Fully loaded:
View attachment 2428811
Saw a cow on the trail:
View attachment 2428812

That's all the same stuff I'm going to do doing this fall. 40 gal LRA tank and I am heat shielding EVERYTHING

 

[silver02accord]

I opened up the fuel tank and the red rubber piece was sitting in the tray. I reinstalled it. It comes off really easy.

 

[suprarx7nut]

Ran Kingston Peak today. I've got an idea now.

If you believe the Torque app duty cycle reading, evap purge is stopped completely on no throttle cruise and remains very low on very low throttle (IE Low range, idling over obstacles). It's at/near 100% during normal road driving. That means the gas tank might not get vented as well during very low speed travel and especially on descent of trails. Purge resumes if you stop the vehicle completely for a few seconds, but as soon as wheels turn, purge stops and then sets itself based on throttle (or load, hard to tell).

I data logged most the trip, so I'll go back and review data, but I think this may partially explain the over-pressure events some people experience. If there's no/little purge while ascending very slowly and literally none on descents where you're not on the gas I could see that building substantial pressure in the tank. Stopping the vehicle would also stop the purge.

I don't get the sense that the evap purge is designed to run in the above scenarios, regardless of tank pressure. If true, I think that's a risky design choice. The purge vapors increase engine load and speed, but that's preferable compared to the violent spewing of fuel, IMO.

I suggest anyone with the spewing issue log their evap purge duty cycle if you can (Torque app with the Advanced LT and EX Plugin worked for me and @J1000 ). I suspect the violent events might be preceeded by prolonged periods of low duty cycle purge (IE tank vapors are trapped in the tank even if pressure rises quickly).

I'm sure the heat reduction efforts help as well, but I think the evap system is failing to do it's job and may be the root cause failure.

 

[silver02accord]

Ran Kingston Peak today. I've got an idea now.

If you believe the Torque app duty cycle reading, evap purge is stopped completely on no throttle cruise and remains very low on very low throttle (IE Low range, idling over obstacles). It's at/near 100% during normal road driving. That means the gas tank might not get vented as well during very low speed travel and especially on descent of trails. Purge resumes if you stop the vehicle completely for a few seconds, but as soon as wheels turn, purge stops and then sets itself based on throttle (or load, hard to tell).

I data logged most the trip, so I'll go back and review data, but I think this may partially explain the over-pressure events some people experience. If there's no/little purge while ascending very slowly and literally none on descents where you're not on the gas I could see that building substantial pressure in the tank. Stopping the vehicle would also stop the purge.

I don't get the sense that the evap purge is designed to run in the above scenarios, regardless of tank pressure. If true, I think that's a risky design choice. The purge vapors increase engine load and speed, but that's preferable compared to the violent spewing of fuel, IMO.

I suggest anyone with the spewing issue log their evap purge duty cycle if you can (Torque app with the Advanced LT and EX Plugin worked for me and @J1000 ). I suspect the violent events might be preceeded by prolonged periods of low duty cycle purge (IE tank vapors are trapped in the tank even if pressure rises quickly).

I'm sure the heat reduction efforts help as well, but I think the evap system is failing to do it's job and may be the root cause failure.

Now that you mention this when I went off road it was mostly downhill and speeds were 20mph ish but with minimal throttle. Hit a few small uphill sections with minimal throttle. Parked the truck for 20 sec to spot an obstacle(engine on, a/c running the whole trip), cleared it quickly but there was significant body roll that I noted. When I got out of the truck to spot, I did not note fuel smell. We went a few feet further and turned around, went back over the obstacle with significant body roll again. We then basically coasted to our parking spot which was like 500 feet or so, backed in and I smelt the vapors and looked to the fuel door.

Is what I am saying is that I didn't notice the smell when I spotted the obstacle, did a nice body roll or two at low speeds over the obstacle with minimal rpms/power needed and coasted to a spot then shut off rig. Then smelt the fuel heavily.

 

[J1000]

@suprarx7nut I think I just spent the previous several months proving that the 06/07 does not have a problem with over pressure. It has a problem with no pressure which leads to boiling, which leads to fuel spewing out the filler neck...because again, it is not pressurized.

edit: I know you just got EVAP duty working and it's new and novel to you but I have been looking at that for months along with tons of other data to get to where I am now. One test I did was try to pressure test my fuel tank/EVAP system with the engine off, with the engine idling, and with the engine at a high-idle of 2000+ RPM where the EVAP duty cycle was higher. In none of the tests could I get any positive pressure in the tank without it leaking out. It would be great if you did the same tests instead of assuming! It's possible your truck has a better functioning EVAP system than mine. One test I will be doing soon is rigging a boost gauge into my fuel tank vent line and running it all the way to the cab so I can actively measure tank pressure while driving. I figure if it stays below 15 psi then it's all good. And hey if you want to ignore everything I've done that's fine, I'll take my 2 MPG and go home.

 

[suprarx7nut]

@suprarx7nut I think I just spent the previous several months proving that the 06/07 does not have a problem with over pressure. It has a problem with no pressure which leads to boiling, which leads to fuel spewing out the filler neck...because again, it is not pressurized.

I disagree. You've shown temperature exacerbates the problem. That doesn't mean temperature is the problem. There's an important difference there. Maybe Toyota/Lexus failed to properly test heat on the 100 series. I don't think that's the case, but maybe it is. Maybe they failed to properly test heat in combination with elevation change. Maybe they failed to test heat in combination with elevation change in combination with low speeds in combination with rocky trails. I think that's more likely.

Here's my take: Boiling is perfectly fine if pressure in the tank never overcomes the system's safety pressure reliefs (of course, higher pressure minimizes boiling so some pressure is a good thing). You need excessively high pressure for any of this to be a problem. Without excess pressure there's zero spewing of gasoline out the filler. For me, it's not a matter of locking in the excess pressure forcefully - it's a matter of the tank venting off that excess properly (through the purge line).

Are people with the spewing gasoline problem overheating the gas? Or is the purge system not purging enough? I don't think we know that yet, but my inclination, especially after seeing how often purge is turned off while offroad, is that the root cause is a lack of purge. Or a dysfunctional purge system (leaking purge hose, clamped hose like @d4nvu found, stuck valve/solenoid, etc...).

If the fuel boils and purge works as designed, there's no issue. The fuel is always losing light ends no matter where it is stored. Typical driving conditions will have the tank hot enough to always be doing this in the summer. That can happen a little faster with more heat, but nobody has posted temps much above common roadway temps of hot climates (~160F).

The heatshielding can help and still not be the root cause. I think that's what we're seeing. It's a good bandaid that keeps the infection managed, but I want to find the root cause.

 

[J1000]

Ok keep assuming. Maybe you're right.

 

[suprarx7nut]

@suprarx7nut I think I just spent the previous several months proving that the 06/07 does not have a problem with over pressure. It has a problem with no pressure which leads to boiling, which leads to fuel spewing out the filler neck...because again, it is not pressurized.

edit: I know you just got EVAP duty working and it's new and novel to you but I have been looking at that for months along with tons of other data to get to where I am now. One test I did was try to pressure test my fuel tank/EVAP system with the engine off, with the engine idling, and with the engine at a high-idle of 2000+ RPM where the EVAP duty cycle was higher. In none of the tests could I get any positive pressure in the tank without it leaking out. It would be great if you did the same tests instead of assuming! It's possible your truck has a better functioning EVAP system than mine. One test I will be doing soon is rigging a boost gauge into my fuel tank vent line and running it all the way to the cab so I can actively measure tank pressure while driving. I figure if it stays below 15 psi then it's all good. And hey if you want to ignore everything I've done that's fine, I'll take my 2 MPG and go home.

What's the design pressure on the late 100 series tank?

How do we know that pressure testing the tank is a valid test?

I think it is possible that the tank design is not intended to hold much pressure at all.

In your test you found a leak at a component that didn't look designed to seal, if I recall. Did you find a failed O-ring or gasket?

 

[OEMGUY0720]

My share:
‘06 LX 246k miles

The symptoms:
- filled her up yesterday at Sam’s gas with regular unleaded (forgot the octane rating)
- automatic stopped at 21 gallons but manually topped off more until I got at 22 gallons on the pump reading
- drove her around for a few errands and one is idling it for 10 to maybe 15 mins (no gas smell yet)
- outside Las Vegas temperature during that time was 106°F
- max speed was only 45MPH
- got home and parked her in her usual spot in the garage, 5 mins after that strong and obvious smell of gas. Had to open the garage door to take out the gas smell
- no drips on the floor or engine bay area (hoses of the fuel line), no spewed gas on the gas cap, no leaks on the gas tank, no smell inside the truck

- Almost 2 weeks ago we were at Dixie National Forest Parks up in Utah (no strong gas smell even after we parked on lots of occasions)
- my gas gauge also is not showing accurate reading, only reads 3/4 full even if the tank is 100% full after filling it up
- outside temperature was at 93°F (highest I think)
- highest elevation we were at was at almost 10,000 feet
- I replaced the truck’s fuel pump and fuel filter 7,000 miles ago (13 months ago - I also went through the stalling issues of the truck last year during one of the hottest days here in Las Vegas, got the fuel pump replaced and never had issues with stalling again).

Now the process of elimination begins.
My question for you gents is, considering the factors I provided, where do you think is the best area to start? Thank you in advance.

 

[Skidoo]

I disagree. You've shown temperature exacerbates the problem. That doesn't mean temperature is the problem. There's an important difference there. Maybe Toyota/Lexus failed to properly test heat on the 100 series. I don't think that's the case, but maybe it is. Maybe they failed to properly test heat in combination with elevation change. Maybe they failed to test heat in combination with elevation change in combination with low speeds in combination with rocky trails. I think that's more likely.

IMO its not Mr Toyota's failure to test, it that the fuel changed. The 100 is 1990s design, even the 2006-07 design had to be completed a number of years before.
Ethanol in gasoline was not a factor during design and was hard to find during production years.

Wikipedia - The ethanol market share in the U.S. gasoline supply grew by volume from just over 1 percent in 2000 to more than 3 percent in 2006. The law promoting ethanol use in US fuel was not passed until 2007 and use ramped up from then.

My own experience with E10 and non-ethanol shows that for the corner cases (of high heat or altitude) where I have high tank pressure with E10 and not when I use non-ethanol. And mine is more challenging as I have a full set of skid plates the retain more heat than stock, but non-ethanol fuel does not have issues with it.

 

[suprarx7nut]

IMO its not Mr Toyota's failure to test, it that the fuel changed. The 100 is 1990s design, even the 2006-07 design had to be completed a number of years before.
Ethanol in gasoline was not a factor during design and was hard to find during production years.

Wikipedia - The ethanol market share in the U.S. gasoline supply grew by volume from just over 1 percent in 2000 to more than 3 percent in 2006. The law promoting ethanol use in US fuel was not passed until 2007 and use ramped up from then.

My own experience with E10 and non-ethanol shows that for the corner cases (of high heat or altitude) where I have high tank pressure with E10 and not when I use non-ethanol. And mine is more challenging as I have a full set of skid plates the retain more heat than stock, but non-ethanol fuel does not have issues with it.

Yep, 100% agreed on all counts.

 

[2001LC]

ECT

I would add A/C on or off when consolidating your averages for ECT by model year. My truck ECT at idle runs a little cooler with A/C off. Also consider measuring Trans Temps in this matrix as well. Higher trans temps will inch ECT slightly higher.

For reference average city/hwy driving in 85-95F ECT runs at 190F with A/C on and stationary indefintely idling in the driveway 186-188 in the same OAT. Trans temps high 130's to low 140's around town summer time. On recent Westward trip driving 15hrs straight in 90~100 OAT ECT were 188-193 and trans temps 148-170. Heat soak has a big impact on ECT & Trans Temp after hours and hours of continuous driving in high OAT.

Good points and info!
OAT as read on dash and actual OAT, A/C frt & rear on or off full cold. Sunny or cloudy. Time of day (afternoon high sun). RPM & MPH. Gear trans & transfer in. Fuel trim readings. IAT (intake air temp), CAT temp in 06-07, Fuel type, altitude, load, towing are all helpful data points when looking at ECT.

For your records, my 06 has the following stats with Dissent armor, sliders, old fan clutch (seems too loud during normal acceleration):

ECT:
Idle on hot day: 198-210F
Highway on hot day: 195F

Air Intake
Idle on hot day: 160F
Highway on hot day: 105-110F


I'm going to replace the fan clutch soon and see if it changes anything.

I'm finding just one radiator(s) fin cleaning, is just is not enough to really get clean. In fact I'm thinking it would be best practice to clean them after all long dusty, bug infested, bush, etc. drives. At minimum we should clean every 10K.

I am going through the 100 series that caught fire thread but wanted to post this asap. I havent had the chance to read this thread it it's entirety but I will in the morning . One more update when on the fwy at 65 plus mph engine coolant temp was between 185 and 196, the outside temp was mostly over 100 deg up to about 113. We stopped for some lunch and shut off truck for 15 minutes. Fired up truck and waited at a drive through I noticed the temp when stopped climbed up to 213 deg. I am thinking to replace fan clutch asap as well. Recently replaced t Stat, new oem rad installed by lexus 2 years ago and new oem rad cap within last month. I should add I run 91 the po had ran 87(it sounds like) and I just had ran through a tank full of chevron injector cleaner which would have been diluted by this time due to 2 fuel tank refills on this trip. Please see my post below from other 100 series catching fire thread sorry for double post:

I am in page 5 of this thread but skipping ahead to post here. I have an 06 LX which I bought 2 months ago. This is the first extended road trip of more than 100 miles continuous. I have wheeled the car at approximately 4 to 6k elevation in Temps up to 100 deg no venting issue noted. Prior to this trip to bishop I replaced the fuel pump, fuel filter and gas cap with oem-the pump is a denso. I replaced thr pump this past week as PM and the truck fired right up. I did not replace fuel sock.

This past weekend I drove from San Diego(sea level) to Bishop approximately 7k elevation. This is about a 6 hour drive the outside temperature was about 90 to 108 degrees for most of the dive. I refueled twice, I am not sure of ethanol content. The most recent refueling was at about 4k feet approximately I filled the tank but did not "too off" beyond thr gas station auto shut off. We stopped at a friend's house at about 6k feet with no noticeable fuel smell. We then climbed another 1k or less to about 7k feet,this portion was mostly off road but speeds in the 20s with a few slow downs for obstacles.

I backed the car into parking spot shut off engine and noticed fuel smell. I looked at fuel tank door and saw visible vapors coming from fuel door. Here is a video link below. When the cap was shut vapors were still coming out. I opened the cap and thr fuel sounded like it was boiling. It took about 15 minutes to stop. The gas tank was approximately 3/4 full at this time.

When I bought the car the PO had maintenance records from Lexus. A cel threw 5 evap codes in March 2020. Per lexus tech: "isolated failure of leak detection pump. Tech recommends replace leak detection pump with vsv and related hoses" There was no cel when I bought it July 2020. I had the following codes come on in my ownership(p0441&p0445 gross leak and incorrect purge flow) I replaced fuel cap with oem and cleared the codes and the codes have not come back at all - it has been approximately 5 weeks.

Fuel door video-i have another showing fuel vapor with fuel door closed prior to opening it but don't think it's helpful.

This is all the details I can think of - maybe I should bite bullet and replace evap system as diagnosed?

FWIW, I have very similar temps on my 06LX. Seemingly healthy engine, but at prolonged hot idle, my ECT climbs past 210F. I am also planning on a new fan clutch (as a good preventative maintenance item if nothing else) and will seek to lower air intake temps. My air intake temps get up to 170F. That seems really f-in hot. I had one time where I tried to start it quickly after shutting down and the engine sputtered and died. I think the intake temps in excess of 170F were a contributor. After a short cool down and getting some air flowing, it fired up and intake temps were below 160.

Keep in mind; the MAF is where IAT is read. If engine is running very hot (210F). The engine compartment is going to be very hot. This can affect air temp in the air box and pipe where MAF is.

ECT jumping high rapidly, while setting and idling w/ACs on to 213F. Is indicative of coolant system issues. Number one being; dirty radiator fins.

Fixed the pinched vapor fuel line (might have blocked venting to my CC)

Ran Kingston Peak today. I've got an idea now.

If you believe the Torque app duty cycle reading, evap purge is stopped completely on no throttle cruise and remains very low on very low throttle (IE Low range, idling over obstacles). It's at/near 100% during normal road driving. That means the gas tank might not get vented as well during very low speed travel and especially on descent of trails. Purge resumes if you stop the vehicle completely for a few seconds, but as soon as wheels turn, purge stops and then sets itself based on throttle (or load, hard to tell).

I data logged most the trip, so I'll go back and review data, but I think this may partially explain the over-pressure events some people experience. If there's no/little purge while ascending very slowly and literally none on descents where you're not on the gas I could see that building substantial pressure in the tank. Stopping the vehicle would also stop the purge.

I don't get the sense that the evap purge is designed to run in the above scenarios, regardless of tank pressure. If true, I think that's a risky design choice. The purge vapors increase engine load and speed, but that's preferable compared to the violent spewing of fuel, IMO.

I suggest anyone with the spewing issue log their evap purge duty cycle if you can (Torque app with the Advanced LT and EX Plugin worked for me and @J1000 ). I suspect the violent events might be preceeded by prolonged periods of low duty cycle purge (IE tank vapors are trapped in the tank even if pressure rises quickly).

I'm sure the heat reduction efforts help as well, but I think the evap system is failing to do it's job and may be the root cause failure.

Now this is interesting:
@d4nvu "Fixed the pinched vapor fuel line (might have blocked venting to my CC)"
@suprarx7nut "That means the gas tank might not get vented as well during very low speed travel and especially on descent of trails."

One of the first things I look at, in getting basic in-line, is' vacuum leaks to/at/on intake manifold!

If engine vacuum not pulling vapor, a pinched line or a bad VSV would certainly contribute to fuel boil issue.

I need to look at the "evap purge" data in my app. Additionally; how the system and when the purge activates. One thought is, vacuum is higher at idle and fuel pump runs slower. So purge may not normally be designed to run.

I've a great deal to learn about the EVAP system!

 

[J1000]

What's the design pressure on the late 100 series tank?

How do we know that pressure testing the tank is a valid test?

I think it is possible that the tank design is not intended to hold much pressure at all.

In your test you found a leak at a component that didn't look designed to seal, if I recall. Did you find a failed O-ring or gasket?

-Who cares. I gained 2 MPG because I stopped leaks.

-Because the EPA requires fuel tanks to hold a certain pressure for a certain period of time in all conditions.

-Ok. I think rainbows are pretty.

-I found nothing that appeared to have failed. I tested the charcoal canister and all valves on the bench. I found an open EVAP line that goes straight to atmosphere on the unmodified system.

 

[suprarx7nut]

-Who cares. I gained 2 MPG because I stopped leaks.

-Because the EPA requires fuel tanks to hold a certain pressure for a certain period of time in all conditions.

-Ok. I think rainbows are pretty.

-I found nothing that appeared to have failed. I tested the charcoal canister and all valves on the bench. I found an open EVAP line that goes straight to atmosphere on the unmodified system.

I'm not sure why there's a tone of animosity, but to be clear, I'm not trying to insult your findings. We're [hopefully] all here to learn about this and improve the knowledge for the community. We're on the same team.

This is like a peer review process. Just because a peer questions your conclusion doesn't mean they're doing anything other than verifying and strengthening your case and helping you better demonstrate it to others.

IMO, MPG claims need a few tanks worth of data. MPG varies a lot trip over trip and tank over tank. Show us the data. If the increase is due to vapor leaks, there's also an important time component. Running through a tank in a day would lose less than if the same volume of gas was consumed over the course of 2 days/weeks/months. 2 MPG is like... 3 gallons of gasoline per tank? That's a high amount of fuel loss. I'm not saying you're wrong, but I am saying that bold a claim needs some hefty data to back it up.

If the EPA has a reg, what is it and how can we test against it in this application?

In the EVAP diagram, where is the open to atmosphere phenomenon? Pic below for reference:

 

[JunkCrzr89]

Who cares. I gained 2 MPG because I stopped leaks.

I don’t think 5-8 days is a sufficient period for making such a definitive conclusion. Your recent graph compares just a few days in September to ~30 days in each month for the past year. If at the end of this month your average for the month is still 2mpg better, then sure there may appear to be *some* evidence to support the claims. As is, simply comparing all of 9/19 to just a handful of days in 9/20 on your graph indicates a rather nominal difference between the two...

 

[J1000]

I don’t think 5-8 days is a sufficient period for making such a definitive conclusion. Your recent graph compares just a few days in September to 30 days in each month for the past year. If at the end of this month your average for the month is still 2mpg better, then sure there may appear to be some evidence to support the claims. As is, simply comparing all of 9/19 to just a handful of days in 9/20 on your graph indicates a rather nominal difference between the two...

Yep absolutely valid. Like I said I did not record any MPG lower than 13.6MPG since the last time I posted which was in the last week of August. You can also see an uptick in last month's average from my fixes. I am confident the trend will continue. Also this month I have driven already over 1000 miles and gone offroading over 10k feet and towed a trailer across town. I'm not a keyboard warrior like a lot of guys.

 

[J1000]

I'm not sure why there's a tone of animosity, but to be clear, I'm not trying to insult your findings. We're [hopefully] all here to learn about this and improve the knowledge for the community. We're on the same team.

Several times in this thread you have stated things that I have omitted in my testing; but were things I explicitly did. Either I am not documenting it correctly (I don't think so) or you are not giving it enough attention to absorb what I've done.

This is like a peer review process. Just because a peer questions your conclusion doesn't mean they're doing anything other than verifying and strengthening your case and helping you better demonstrate it to others.

Yes, that is why I challenged you to try and pressurize your tank. Even to .5 PSI. I tried and failed. I think it's a valid test. After my mods I was able to pressurize it to 30 psi.

IMO, MPG claims need a few tanks worth of data. MPG varies a lot trip over trip and tank over tank. Show us the data. If the increase is due to vapor leaks, there's also an important time component. Running through a tank in a day would lose less than if the same volume of gas was consumed over the course of 2 days/weeks/months. 2 MPG is like... 3 gallons of gasoline per tank? That's a high amount of fuel loss. I'm not saying you're wrong, but I am saying that bold a claim needs some hefty data to back it up.

And I have posted an open link that anyone in the world can view my MPG for my vehicle. I have done so many times here I will do it again: LX470 (Lexus LX470) | Fuelly

2MPG on these vehicles is a 15-20% improvement. Please, where else can I find a 15-20% improvement in my MPG on a vehicle with less than $100 in parts and minimal labor?? You are discounting a serious improvement. I plan to drive this vehicle for another 200k at least, do the math.

Not only that but the reduction in fire hazard from open fumes, embarrassment from having a truck that stinks every time you park it, and venting fuel straight into the atmosphere just to breath it into your own lungs.

If the EPA has a reg, what is it and how can we test against it in this application?

epa.gov

In the EVAP diagram, where is the open to atmosphere phenomenon? Pic below for reference:
View attachment 2429907

Exactly where you pen is pointing. I thought I illustrated this very well in my post #364 several pages back: Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen?

Which brings us back to how you're asking a lot of questions that lead me to think you aren't really paying attention.