Gas tank building excessive pressure & fuel smell. Dangerous for sure! Why does this happen? (1 Viewer)

[suprarx7nut]

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.

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.


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.

epa.gov

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.

Numbered so I can keep track of each topic/point:

1. I have not tried to pressurize per the manual. I don't have a gauge that can faithfully show .5 psi. Can you share what gauge you used to show fractions of 1 psi? I think I'll need to buy something like a bike pump. All i have are pneumatic air tools and gauges that are 0-200 psi gauges. I can't tell a supply pressure of .7 psi from .5 psi.

2. Can you pull the fuelly data into an excel spreadsheet and pull up the std dev? I'm guessing it's at least 1.5-2 MPG which means from a statistical standpoint we'll need to have a lot of post-fix data to tell what the improvement is.

3. I'm not discounting how nice that improvement might be. It's amazing - if true. If you can gain 2MPG for $100 and reduce emissions that would likely be the "mod of the decade on 'mud". The benefit of the proposition doesn't make me less likely to question it - quite the opposite.

4. EPA - you can't just link the epa website, haha. Provide a numeric value for the proper pressure of the 100 tank. Numerical digits and a source.

5. That's an intentional non-sealing joint - it's the air inlet. That's not meant to seal. The diagram shows that area to be non-sealing. The sealing mechanisms for that line are presumably a combination of the upstream air filter (which may contain a check valve), Vent Valve, refueling valve and perhaps other mechanisms not labeled on that diagram. You say you found a leaking component - I say that was never meant to seal and the failure *may* be further upstream in one of those other components that was, IMO, the intended mechanism for preventing outward pressure loss through that line, but very easily allowing air to come into the tank.

*Additionally, if your gauge for step 1 was allowing .7 psi and the tank is only supposed to hold .5 psi, perhaps you were just overpowering the built in pressure controls. I doubt the tank is limited to only .5 psi, but I'm saying we need some specs to say otherwise. We don't seem to have those specs so it's a hard pill to swallow to say the tank must have a failure because it wouldn't hold pressure.

 

[J1000]

Numbered so I can keep track of each topic/point:

1. I have not tried to pressurize per the manual. I don't have a gauge that can faithfully show .5 psi. Can you share what gauge you used to show fractions of 1 psi? I think I'll need to buy something like a bike pump. All i have are pneumatic air tools and gauges that are 0-200 psi gauges. I can't tell a supply pressure of .7 psi from .5 psi.

You can use a digital tire pressure gauge like this one: https://amzn.to/2Fe5buH Or you can use an analog gauge + your brain. That's what I did.

2. Can you pull the fuelly data into an excel spreadsheet and pull up the std dev? I'm guessing it's at least 1.5-2 MPG which means from a statistical standpoint we'll need to have a lot of post-fix data to tell what the improvement is.

Feel free it's publicly available and you obviously know more about what you're trying to do than I do.

3. I'm not discounting how nice that improvement might be. It's amazing - if true. If you can gain 2MPG for $100 and reduce emissions that would likely be the "mod of the decade on 'mud". The benefit of the proposition doesn't make me less likely to question it - quite the opposite.

Does your truck smell like gas when you park? yes/no.

4. EPA - you can't just link the epa website, haha. Provide a numeric value for the proper pressure of the 100 tank. Numerical digits and a source.

Yes I can. It falls under the category of "No duh." Everyone knows that evaporative emissions are one of the leading causes of greenhouse gases in the atmosphere, and the subject of many regulations, both federal and state. We know that in CA the fuel pumps have covers on them to stop evaporative emissions and that basically every car that any of us has owned in our lifetimes has made a "hiss" when opening the gas cap.

But just as proof that I am here in good faith. Here is your precious citation: http://www.meca.org/resources/US_Evap_History_and_General_Findings_1-31-20_FINAL.pdf
" As mentioned above, ORVR regulations were first proposed in 1987 and after considerable public review and debate were published by EPA in April 1994.38 Implementation began with the 1998 model year for LDVs and 2001 for LDTs. ORVR test procedures are based on the drive cycles in the Enhanced Evaporative rule with a standard of 0.20 g/gallon. California adopted ORVR in 1995 with implementation in the 1998 model year.39 ORVR based on the U.S. EPA test procedures is a nationwide requirement.40 Finally, as part of its comprehensive approach to dealing with evaporative emissions, in 1992 CARB adopted an OBD monitoring requirement that fuel system vapor leaks with a cumulative diameter equal to or greater than 0.040” be identified and that a malfunction indicator light (MIL) be illuminated on the vehicle. The requirement was implemented for LDVs and LDTs for the 1994 model year. In 1994, CARB upgraded this OBD evaporative leak threshold to a cumulative diameter of 0.020” or greater effective for the 1996 model year. Following requirements in the 1990 Clean Air Act Amendments (CAAA), EPA adopted similar but not identical evaporative system monitoring requirements in 1993, and these were eventually fully implemented for the 1996 model year.41 (The difference was in test procedure, not the numerical value monitoring threshold.) In 1998 EPA fully aligned with CARB OBD II evaporative monitoring test procedures. EPA accepted CARB certifications to 0.020” as compliant with the 0.040” Federal standard. EPA eventually adopted the 0.020” value for the 2018 model year.42 OBD systems also monitor the continued proper operation of the evaporative control system purge valve. Overall, OBD for evaporative control systems are useful as an environmental tool because failure of a purge valve or development of a fuel system vapor leak is an indicator that the vehicle would likely fail the hot soak+diurnal emission standard. It is also a useful tool in screening the performance of vehicles in emission inspection/maintenance programs and to provide data for inventory modeling. However, OBD itself is a monitoring requirement and the illumination of the MIL by OBD itself does not specifically prohibit leaks or purge valve failures "

5. That's an intentional non-sealing joint - it's the air inlet. That's not meant to seal. The diagram shows that area to be non-sealing. The sealing mechanisms for that line are presumably a combination of the upstream air filter (which may contain a check valve), Vent Valve, refueling valve and perhaps other mechanisms not labeled on that diagram. You say you found a leaking component - I say that was never meant to seal and the failure *may* be further upstream in one of those other components that was, IMO, the intended mechanism for preventing outward pressure loss through that line, but very easily allowing air to come into the tank.

Prove it. As I stated many times in this thread I rebuilt my charcoal canister and checked all the valves on the bench. They were functioning. Prove to us that yours functions correctly, I challenge you.

*Additionally, if your gauge for step 1 was allowing .7 psi and the tank is only supposed to hold .5 psi, perhaps you were just overpowering the built in pressure controls. I doubt the tank is limited to only .5 psi, but I'm saying we need some specs to say otherwise. We don't seem to have those specs so it's a hard pill to swallow to say the tank must have a failure because it wouldn't hold pressure.

Ok I guess you just don't believe me? Do you think, without any tools and just your fingernail and a schrader valve, you could tell if there was 0 psi or .5 psi in a sealed chamber? Go ahead, call me a liar directly because I am tired of typing.

 

[whirlybirdbrewing]

You should start a neat sidebar thread where you can duke it out. Maybe even throw a few expletives out. It's the internet after all so you're basically invincible. I have no doubt there are keyboard real warriors here.

I'll stay subbed to this thread though as I have had a couple instances of this and I'm curious as to the fixes. I don't think chasing MPGs and trying to seal a vehicle tank to hold excessive pressure is the right way forward. These things are designed to vent as are most all fuel cells.

As far as my non-data, data points go:

First time was an early July run to the Western Sierras (~10K). OAT ranged from 70-95F. Never shut off the truck but to the line of thinking regarding venting @suprarx7nut brought up, the trip was a slow climb for about 3 hours, rarely getting over 40. When I finally shut down I noticed the fuel smell and vapor pouring out of the cap.

Second time was this past weekend in the Western Sierras. Much lower altitude (~4k) but significantly hotter. 5 hour drive through the Central Valley where it was all triple digits. Cut off I-5 to slower, winding roads and temps stayed in the 100-110 range. Last 30 minutes of the drive were all on pavement but under 30 mph. After I stopped and shut down, similar fuel boil / off gassing as before. This time I tried to restart the engine but it wasn't having it. Rough idle then just die. 5-10 minutes later, it would run for a couple of sputters then die. I ended up cracking the fuel cap to let everything vent and depressurize. After another 10 minutes, engine started without issue.

AC always running because it's hot out. Dissent bumpers and full skid plates. I have no gauge data (although I just bought a BlueDrive while reading the 21+ pages) but all the needles seemed happy and steady.

I wouldn't suspect that we uncovered a hidden Achilles Heal or huge miss in the development of the truck. Rather, everyone is probably on to one of many contributing factors. Things are engineered with certain margins. Excess ECT from a coolant system that is operating <100% eats into those margins. Excess heat build-up from aftermarket parts that either increase vehicle load or reduce stock airflow (or both) also eat into that margin. A shift in fuel composition to more ethanol may also eat into those margins.

What I'd offer is that we are seeing the cumulative effects of these items and I'm happy the group is tackling fixes that chip away the problem. Happy to data mine for anyone. 06 LX.

 

[J1000]

You should start a neat sidebar thread where you can duke it out. Maybe even throw a few expletives out. It's the internet after all so you're basically invincible. I have no doubt there are keyboard real warriors here.

That's what drives me crazy about @suprarx7nut, he met me in person on the dyno. He saw my truck. He knows it's maintained. He knows I am a better wrencher than he is. He knows I am serious. But he won't read what I type here.

I don't think chasing MPGs and trying to seal a vehicle tank to hold excessive pressure is the right way forward

A. What is "excessive pressure?" Did you know US gasoline regulations limit fuel vapor pressure to 9 psi in the winter?

B. Why not? We know these trucks smell like gas. We know the fuel boils. We know that when there is pressure, there is no boiling. We know that gas = $$$ and saving $$$ =

 

[J1000]

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.

Actually, this is an opinion based on anti-ethanol sentiments and not fact.

In actuality, Lexus/Toyota EVAP systems were revised in late 2002 because the Clean Air Act was updated in 2002 and the EPA began requiring the new standards in December 2002. This is likely why the 2003+ 100 Series has a totally reworked EVAP system compared to the pre-2002.

The key detail being that the EPA relaxed the gasoline RVP (vapor pressure) requirements for gasoline containing ethanol down to 7.8psi. This is why during my testing I found my OEM Lexus fuel cap was venting pressure at 7.8 psi. So, in fact, Toyota specifically redesign the 100 Series for the 2003 model year to accomodate ethanol fuels and vent more pressure than before, the EPA was specifically allowing it.

Reformulated Gasoline | US EPA

Reformulated gasoline (RFG) is gasoline blended to burn cleaner and reduce smog-forming and toxic pollutants in the air we breathe. The Clean Air Act requires that RFG be used to reduce harmful emissions of ozone.

www.epa.gov

 

[Eyedaho]

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:

View attachment 2429216View attachment 2429217

That's what drives me crazy about @suprarx7nut, he met me in person on the dyno. He saw my truck. He knows it's maintained. He knows I am a better wrencher than he is. He knows I am serious. But he won't read what I type here.


A. What is "excessive pressure?" Did you know US gasoline regulations limit fuel vapor pressure to 9 psi in the winter?

B. Why not? We know these trucks smell like gas. We know the fuel boils. We know that when there is pressure, there is no boiling. We know that gas = $$$ and saving $$$ =

Lulz. Have you checked out the Covid threads? I'm thinking you'd enjoy the dynamic of those conversations.

 

[bluesquirrel]

I don't think the 100 series was meant to have a V8 put in it.

Lulz. Have you checked out the Covid threads? I'm thinking you'd enjoy the dynamic of those conversations.

Nice.

Adding to the hysteria. Don't fight me too hard

 

[JunkCrzr89]

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...

2. Can you pull the fuelly data into an excel spreadsheet and pull up the std dev? I'm guessing it's at least 1.5-2 MPG which means from a statistical standpoint we'll need to have a lot of post-fix data to tell what the improvement is.

Feel free it's publicly available and you obviously know more about what you're trying to do than I do.

To interject some science into this discussion, I pulled all of the MPG data that @J1000 had on Fuelly. There's a total of 169 fuel-ups on there, spanning from August 2018 to September 2020; however, 16 of those did not have MPG data, so the final dataset is comprised of n = 153 data points. Summaries are below:

Distribution of MPGs combined across months and years, with mean, median, standard deviation (SD), and where 95% of the values lie (between the dashed orange lines; i.e., -/+ 2*SD). You can see that 95% of the MPG values fall between 8.56 and 16.04 MPGs. So, anecdotally, just based on the raw data, the 2 MPG increase claim by @J1000 doesn't have much, if any, support.

Here's the raw data across time (blue line) with an estimated Loess smoothing spline from a generalized additive model (orange line) and the associated 95% uncertainty intervals (gray shaded area; *not confidence intervals*). Dates on the x-axis are Year-Month-Day. You can some evidence of seasonal fluctuations here, perhaps corresponding to seasonal gas blends. Note that summer blends and winter blends are introduced in CO (where @J1000 lives) by May 1 and September 16 of each year, respectively, but I need to fit a model with blend as a covariate to see if such an effect actually exists. Nevertheless, the 2 MPG increase claim doesn't have much support across time either; again, based solely on the raw data values.

To directly investigate @J1000 claim of a 2MPG increase, we'll have to wait until he's done collecting data for the entirety of September 2020. His changes to the fuel/EVAP/cooling systems were made at the end of August, so we should at least give it a full month of data collection. However, we can use the data from previous months to in a time series analysis to predict what his expected MPG value will be for September 2020 and then compare that to his final MPG value for September 2020. To do this, I subset his data into model data and test data, whereby models were fit to the MPG data for August 2018-September 2019 and the test data used for model validation (accuracy testing) were the MPG data for October 2019-September 2020. I then fit some exponential smoothing state space models to the data without any covariates (e.g., excluding seasonal gas blend from consideration).

I got tired of making fancy figures so you get just a basic output of results here. The first box shows the raw data (average monthly MPG) with a smoother applied, the second box shows the predicted values from the best model, the third box shows the estimated longitudinal trend over the entire period, and the fourth box shows the estimated amount of unexplained variation that exists. Prediction accuracy from the best model was quite good despite the small amount of data, having an RMSE = 1.19 and Theil's U = 0.75 (U < 1 means that the model is better than informed guessing).

Ultimately, the model predicts that @J1000 MPG for September 2020 will be 12.65 (95% PI: 8.5-17.8). Note that the current ~14 MPG that he's observed over the last week or so is well within the 95% prediction interval. Thus, the 2 MPG increase claim is thus far not supported, is within 95% of the observed data over the last 2 years, or is likely due to chance alone or simple random/unexplained variation. However, the caveat is that, as noted above, he has very few data points since making all of the changes to his Cruiser, so again, we can reevaluate at the end of the month.

 

[suprarx7nut]

You can use a digital tire pressure gauge like this one: https://amzn.to/2Fe5buH Or you can use an analog gauge + your brain. That's what I did.

Feel free it's publicly available and you obviously know more about what you're trying to do than I do.

Does your truck smell like gas when you park? yes/no.


Yes I can. It falls under the category of "No duh." Everyone knows that evaporative emissions are one of the leading causes of greenhouse gases in the atmosphere, and the subject of many regulations, both federal and state. We know that in CA the fuel pumps have covers on them to stop evaporative emissions and that basically every car that any of us has owned in our lifetimes has made a "hiss" when opening the gas cap.

But just as proof that I am here in good faith. Here is your precious citation: http://www.meca.org/resources/US_Evap_History_and_General_Findings_1-31-20_FINAL.pdf
" As mentioned above, ORVR regulations were first proposed in 1987 and after considerable public review and debate were published by EPA in April 1994.38 Implementation began with the 1998 model year for LDVs and 2001 for LDTs. ORVR test procedures are based on the drive cycles in the Enhanced Evaporative rule with a standard of 0.20 g/gallon. California adopted ORVR in 1995 with implementation in the 1998 model year.39 ORVR based on the U.S. EPA test procedures is a nationwide requirement.40 Finally, as part of its comprehensive approach to dealing with evaporative emissions, in 1992 CARB adopted an OBD monitoring requirement that fuel system vapor leaks with a cumulative diameter equal to or greater than 0.040” be identified and that a malfunction indicator light (MIL) be illuminated on the vehicle. The requirement was implemented for LDVs and LDTs for the 1994 model year. In 1994, CARB upgraded this OBD evaporative leak threshold to a cumulative diameter of 0.020” or greater effective for the 1996 model year. Following requirements in the 1990 Clean Air Act Amendments (CAAA), EPA adopted similar but not identical evaporative system monitoring requirements in 1993, and these were eventually fully implemented for the 1996 model year.41 (The difference was in test procedure, not the numerical value monitoring threshold.) In 1998 EPA fully aligned with CARB OBD II evaporative monitoring test procedures. EPA accepted CARB certifications to 0.020” as compliant with the 0.040” Federal standard. EPA eventually adopted the 0.020” value for the 2018 model year.42 OBD systems also monitor the continued proper operation of the evaporative control system purge valve. Overall, OBD for evaporative control systems are useful as an environmental tool because failure of a purge valve or development of a fuel system vapor leak is an indicator that the vehicle would likely fail the hot soak+diurnal emission standard. It is also a useful tool in screening the performance of vehicles in emission inspection/maintenance programs and to provide data for inventory modeling. However, OBD itself is a monitoring requirement and the illumination of the MIL by OBD itself does not specifically prohibit leaks or purge valve failures "


Prove it. As I stated many times in this thread I rebuilt my charcoal canister and checked all the valves on the bench. They were functioning. Prove to us that yours functions correctly, I challenge you.


Ok I guess you just don't believe me? Do you think, without any tools and just your fingernail and a schrader valve, you could tell if there was 0 psi or .5 psi in a sealed chamber? Go ahead, call me a liar directly because I am tired of typing.

That's what drives me crazy about @suprarx7nut, he met me in person on the dyno. He saw my truck. He knows it's maintained. He knows I am a better wrencher than he is. He knows I am serious. But he won't read what I type here.


A. What is "excessive pressure?" Did you know US gasoline regulations limit fuel vapor pressure to 9 psi in the winter?

B. Why not? We know these trucks smell like gas. We know the fuel boils. We know that when there is pressure, there is no boiling. We know that gas = $$$ and saving $$$ =

Call you a liar? Better wrencher? Where am I and what's going on?

We've met in person - better yet, collaborated to give this community some hard data on a different contentious topic. We should have enough rapport that you know I'm not challenging your assertions to be mean. I think if we covered this same conversation over some bourbon we could have made the same points and not gotten here.

I'm not sure where I went wrong in the back and forth, but I'd rather not continue down a detrimental path so I'm not going to continue to volley right now.

To interject some science into this discussion, I pulled all of the MPG data that @J1000 had on Fuelly. There's a total of 169 fuel-ups on there, spanning from August 2018 to September 2020; however, 16 of those did not have MPG data, so the final dataset is comprised of n = 153 data points. Summaries are below:

Distribution of MPGs combined across months and years, with mean, median, standard deviation (SD), and where 95% of the values lie (between the dashed orange lines; i.e., -/+ 2*SD). You can see that 95% of the MPG values fall between 8.56 and 16.04 MPGs. So, anecdotally, just based on the raw data, the 2 MPG increase claim by @J1000 doesn't have much, if any, support.
View attachment 2430246

Here's the raw data across time (blue line) with an estimated Loess smoothing spline from a generalized additive model (orange line) and the associated 95% uncertainty intervals (gray shaded area; *not confidence intervals*). Dates on the x-axis are Year-Month-Day. You can some evidence of seasonal fluctuations here, perhaps corresponding to seasonal gas blends. Note that summer blends and winter blends are introduced in CO (where @J1000 lives) by May 1 and September 16 of each year, respectively, but I need to fit a model with blend as a covariate to see if such an effect actually exists. Nevertheless, the 2 MPG increase claim doesn't have much support across time either; again, based solely on the raw data values.
View attachment 2430248

To directly investigate @J1000 claim of a 2MPG increase, we'll have to wait until he's done collecting data for the entirety of September 2020. His changes to the fuel/EVAP/cooling systems were made at the end of August, so we should at least give it a full month of data collection. However, we can use the data from previous months to in a time series analysis to predict what his expected MPG value will be for September 2020 and then compare that to his final MPG value for September 2020. To do this, I subset his data into model data and test data, whereby models were fit to the MPG data for August 2018-September 2019 and the test data used for model validation (accuracy testing) were the MPG data for October 2019-September 2020. I then fit some exponential smoothing state space models to the data without any covariates (e.g., excluding seasonal gas blend from consideration).

I got tired of making fancy figures so you get just a basic output of results here. The first box shows the raw data (average monthly MPG) with a smoother applied, the second box shows the predicted values from the best model, the third box shows the estimated longitudinal trend over the entire period, and the fourth box shows the estimated amount of unexplained variation that exists. Prediction accuracy from the best model was quite good despite the small amount of data, having an RMSE = 1.19 and Theil's U = 0.75 (U < 1 means that the model is better than informed guessing).
View attachment 2430262

Ultimately, the model predicts that @J1000 MPG for September 2020 will be 12.65 (95% PI: 8.5-17.8). Note that the current ~14 MPG that he's observed over the last week or so is well within the 95% prediction interval. Thus, the 2 MPG increase claim is thus far not supported, is within 95% of the observed data over the last 2 years, or is likely due to chance alone or simple random/unexplained variation. However, the caveat is that, as noted above, he has very few data points since making all of the changes to his Cruiser, so again, we can reevaluate at the end of the month.

I would have settled for the standard deviation, but I'll take the distribution, trend and other plots. Kudos to figuring out how to extract the data (I'm sure there was a download link, but I wasn't seeing it) and thanks for giving us a confidence interval. I'm happy with my 1.5-2.0 estimate when the answer was 1.87.

 

[silver02accord]

Call you a liar? Better wrencher? Where am I and what's going on?

We've met in person - better yet, collaborated to give this community some hard data on a different contentious topic. We should have enough rapport that you know I'm not challenging your assertions to be mean. I think if we covered this same conversation over some bourbon we could have made the same points and not gotten here.

I'm not sure where I went wrong in the back and forth, but I'd rather not continue down a detrimental path so I'm not going to continue to volley right now.



I would have settled for the standard deviation, but I'll take the distribution, trend and other plots. Kudos to figuring out how to extract the data (I'm sure there was a download link, but I wasn't seeing it) and thanks for giving us a confidence interval. I'm happy with my 1.5-2.0 estimate when the answer was 1.87.

I know everyone on MUD is a better wrencher than me.

 

[JunkCrzr89]

I would have settled for the standard deviation, but I'll take the distribution, trend and other plots. Kudos to figuring out how to extract the data (I'm sure there was a download link, but I wasn't seeing it) and thanks for giving us a confidence interval. I'm happy with my 1.5-2.0 estimate when the answer was 1.87.

Eh, I wanted to know more than the SD, which can be less informative if data are not approximately normally distributed, but these MPGs do follow a Gaussian probability distribution quite well.

 

[jerryb]

here you have people venting fuel caps, same as heating fuel in an open tin can on your kitchen stove. Then re fueling not even thinking about what just happened and whats left in the tank.

you have a slug or multiple slugs of gas, not liquid, that is expanding and attempting to equalize on the other side of a check valve in the middle between the tank and the rails. That slug is expanding 3.5 times the volume from a starting point of 40 psig.
oh, ya, temp is increasing on the rail side the entire time from when the key is off until they equalize hours and hours later.
temp goes up, volume increases, pressure remains constant because the pressure is being bleed off on the regulator on the rail to the return line. At the same time the regular leakdown on the rail is happening so actual pressure is going down from the pump feed to the fpr check, expanding volume even more.
There is a check on the pump supply, there is a check bleed at the fpr. The return line should always be open and @ zero psig until it overcomes the tank vents and comes out the easiest exit.
You're distilling fuel, now you have a heavy mix in the tank with even a greater % of water. And you fill up again.
And argue about what? gas mileage? or saving the environment?
I'd love it if you guys could keep it going. I still don't get why there's 20 pages of why fuel boils. Hopefully when fuel gets expansive again and they're all ticking time bomb fuel boil monsters I can get another vvti for cheap.

 

[silver02accord]

I was looking to replace VSV in engine bay. I took a pic of my part number which is 90910-12259, stamped Toyota and Denso. When looking for a replacement partsouq and conicelli toyota are not showing that this fits my 06 LX. Can someone with an 06 LX/LC take a picture of their VSV on DS near manifold? Fairly certain this part is original.

 

[JunkCrzr89]

Did you know US gasoline regulations limit fuel vapor pressure to 9 psi in the winter?

That's only for the summer "ozone" period (May 1 - Sept. 15), not winter. Winter allowable is up to 15 psi in most states, including CO (https://www.colorado.gov/pacific/atom/18701).

Note that if you're buying gas in these CO counties between June 1 and Sept. 15, the allowable vapor pressure is only 7.8 psi. (Gasoline Reid Vapor Pressure | US EPA):

 

[Eyedaho]

That's only for the summer "ozone" period (May 1 - Sept. 15), not winter. Winter allowable is up to 15 psi in most states, including CO (https://www.colorado.gov/pacific/atom/18701).

View attachment 2430894

Note that if you're buying gas in these CO counties between June 1 and Sept. 15, the allowable vapor pressure is only 7.8 psi. (Gasoline Reid Vapor Pressure | US EPA):

View attachment 2430895

Interesting that the lower vapor pressure counties are due to ozone nonattainment. I wouldn't have pictured CO having air quality issues.

 

[JunkCrzr89]

Interesting that the lower vapor pressure counties are due to ozone nonattainment. I wouldn't have pictured CO having air quality issues.

5 million people live in the Front Range, which is where all those counties are. That's on par with Phoenix, and we have horrible air quality issues here...

 

[Eyedaho]

5 million people live in the Front Range, which is where all those counties are. That's on par with Phoenix, and we have horrible air quality issues here...

Fair point! I guess the population density has increased there much more than I thought. I don't travel to that area very often, since I have to pass by so much cool stuff to get there.

 

[Jcrider48]

Does everyone with this fuel issue have aftermarket skids? Are the skids allowing heat to build up around the fuel lines…?

 

[JunkCrzr89]

Does everyone with this fuel issue have aftermarket skids? Are the skids allowing heat to build up around the fuel lines…?

No and probably.

 

[suprarx7nut]

Does everyone with this fuel issue have aftermarket skids? Are the skids allowing heat to build up around the fuel lines…?

Everyone have aftermarket skids: definitely not. It's an issue with factory shields. I experienced it with my 99 with factory shields.

Skid plates probably make the issue worse by trapping exhaust heat. Since multiple users have noted reduction (or elimination) of the issue by adding heat shielding or relocating fuel lines I think we're confident heat in the underside is a contributor.