How many MPB (miles per bar)?

[Krusher]

Originally Posted by 1stToyota

The gas cap says "Tighten" 1-click (not "fill" to 1-click) because if you don't click it the fuel tank pressure sensor voltage will read high and the PCM will assume that someone is driving around with a loosened or removed gas cap.

Ok, time to dumb it down a bit... the CEL comes on for more than just the gas cap being off... or loose.

When the ECM goes into self-check it will run the evap system... if the pressures/volts do not fall within a specified range then the CEL will trip.

The gas cap not being installed or being loose has nothing to do with the evap canister... which can become soaked with fuel when topping off. This also has the potential to trip the CEL. Odds? Probably 1 in a million (est) cars will end up having to prematurely replace the canister due to overfilling.

Lesson? Read the entire post before commenting... and don't top off your tank... that extra squirt or 2 is not worth the cost of a new evap canister.

[1stToyota]

Originally Posted by Krusher

Ok, time to dumb it down a bit... the CEL comes on for more than just the gas cap being off... or loose.

Yeah, we'll dumb it way down. The cap reads "Tighten 1-click" or PCM may trip a code, not "Fill until nozzle clicks once"

When the ECM goes into self-check it will run the evap system... if the pressures/volts do not fall within a specified range then the CEL will trip.

MIL

The gas cap not being installed or being loose has nothing to do with the evap canister...

Evap **system**...How do you expect the fuel pressure sensor to read right with a loose or malfunctioning fuel cap? Out of spec readings = PCM storing a code. Cap warning is all about the cap being tight and has nothing to do with fuel top-off.

which can become soaked with fuel when topping off.

How?

Fuel filler pipe and vent has nothing to do with the cansiter, vent and purge solenoids, or EVAP hoses and lines. When you're filling the tank the filler tube and vent go straight into the tank, they don't spill over to other components. Most filler pipes/hoses now have the vent hose built within the filler hose itself, older designs had the vent hose opening up near the top of the filler pipe, but the vent hose still dumped into the fuel tank, about 2-3 inches from the filler hose inlet at the tank.

This also has the potential to trip the CEL. Odds? Probably 1 in a million (est) cars will end up having to prematurely replace the canister due to overfilling.

Overfilling will soil your pants or shoes, it won't run down the vent tube into the canister, especially when most of those canisters are at the other end of the vehicle and the hoses and/or canisters are above the tank level.

If overfilling ruined the EVAP system then I guess there would be warnings about never parking a vehicle on a slope.

Lesson? Read the entire post before commenting... and don't top off your tank... that extra squirt or 2 is not worth the cost of a new evap canister.

Lesson: Read your cap. The instructions are simple enough to follow.

Canisters get damaged while the car is running, running improperly and a faulty EVAP system, has nothing to do with topping off a fuel tank.

[Krusher]

MIL (Malfunction Indicator Light) = CEL (Check Engine Light) I know it's hard to believe... but it's true. Why do I call it a CEL? Because that's what the domestic industry calls it... that's what I'm used to... oh well, get over it.

Take a charcoal canister and soak it in fuel... it will get.... soaked... Why can the canister get soaked? Ok... I'm going to go a little bit into the system:

For the evap system self-test: Using the engine's vacuum, via the intake, the tank will be brought to a vacuum. If it is unable to pull a vacuum a code will set off the CEL. (Either small or large leak, depending on if the tank can pull a vacuum but not hold it, or not pull a vacuum at all... this can happen by the purge/vacuum valve sticking open/closed (checked by either forcing PIDs and/or plugging the vent per pinpoint tests), the gas cap o-ring not sealing the fill pipe(checking the condition of the cap or doing an actual pressure test on it), or an actual hole in the system(smoke testing... my favorite)) If it is able to pull a vacuum and hold it for a specified period of time it will release the vacuum into the charcoal canisters by sending a 12V signal (or completing the ground, depending on how the system is designed) to the purge valve solenoid which will open the tank to atmosphere. This line is typically vented to the fuel fill area. Now here comes the physics lesson...

Pull a vacuum and then let it go... what happens? 14.7# air will push it's way into the tank. Ever blow onto a liquid? What happens? It moves, doesn't it? Now put your face closer to the liquid and do the same thing (simulating putting more fuel into the tank)... get it close enough and your face will get a little wet... Now do this over the course of 8 years or 80,000 miles (epa mandated emissions warranty). My guess is that your face will be wetter then if you pulled your face away a little bit.

Your charcoal canister is getting the same thing... They are not designed to last forever... they do have a operational life since they are supposed to see a minimal, and engineered, amount of fuel vapor. If you put more liquid into the canister it will shorten it's life... by how much? Unknown to me, but if you're keeping your car don't you not want to spend about $300 for a canister until you really have to?

Although it seems that some people don't think that an eye dropper can fill a bucket one drop at a time...

If overfilling ruined the EVAP system then I guess there would be warnings about never parking a vehicle on a slope.

This is an engineering concern and a fuel tank, if you notice, has been designed to eliminate that concern.

Canisters get damaged while the car is running, running improperly and a faulty EVAP system, has nothing to do with topping off a fuel tank.

Guess what... when you top off the tank and you start the car... I know it's hard to believe, but the car is running... and your evap system will be conducting it's business with more fuel than was engineered to do so until you drive for a while!

Unfortunately I actually dumbed it down so that I didn't have to actually go into the operation of the system and just plainly say that overfilling the tank can cause problems... but since you found it necessary to try and "dumb it down" further by being technical I find it necessary to correct you.

Again, read the full post.

^Good write-up - It's like an episode of Mythbusters.

I find this amusing since the write up was written "Yeah, we'll dumb it way down." Mythbusters uses technical procedures to either prove or disprove a theory. They don't dumb it down...

Waiting for your reply...

[1stToyota]

Originally Posted by Krusher

MIL (Malfunction Indicator Light) = CEL (Check Engine Light) I know it's hard to believe... but it's true. Why do I call it a CEL? Because that's what the domestic industry calls it... that's what I'm used to... oh well, get over it.

You're trying to sound smart, eventho' you confuse the gas cap instructions, so use the modern term.

Take a charcoal canister and soak it in fuel... it will get.... soaked... Why can the canister get soaked? Ok... I'm going to go a little bit into the system:

For the evap system self-test: Using the engine's vacuum, via the intake, the tank will be brought to a vacuum. If it is unable to pull a vacuum a code will set off the CEL. (Either small or large leak, depending on if the tank can pull a vacuum but not hold it, or not pull a vacuum at all... this can happen by the purge/vacuum valve sticking open/closed (checked by either forcing PIDs and/or plugging the vent per pinpoint tests), the gas cap o-ring not sealing the fill pipe(checking the condition of the cap or doing an actual pressure test on it), or an actual hole in the system(smoke testing... my favorite)) If it is able to pull a vacuum and hold it for a specified period of time it will release the vacuum into the charcoal canisters by sending a 12V signal (or completing the ground, depending on how the system is designed) to the purge valve solenoid which will open the tank to atmosphere. This line is typically vented to the fuel fill area. Now here comes the physics lesson...

Vacuum? As in engine running or applying vacuum with hand pump? Doesn't happen while filling tank at gas station.

Pull a vacuum and then let it go... what happens? 14.7# air will push it's way into the tank. Ever blow onto a liquid? What happens? It moves, doesn't it? Now put your face closer to the liquid and do the same thing (simulating putting more fuel into the tank)... get it close enough and your face will get a little wet... Now do this over the course of 8 years or 80,000 miles (epa mandated emissions warranty). My guess is that your face will be wetter then if you pulled your face away a little bit.

Your charcoal canister is getting the same thing... They are not designed to last forever... they do have a operational life since they are supposed to see a minimal, and engineered, amount of fuel vapor. If you put more liquid into the canister it will shorten it's life... by how much? Unknown to me, but if you're keeping your car don't you not want to spend about $300 for a canister until you really have to?

My car is covered bumper-to-bumper for 7 years/75K miles (excluding typical maintenance items, carpet, etc...), but that's beside the point. If topping off tanks = flooded charcoal canisters Toyota and every other manufacturer would be covering about 23,000 (est) warranties everyday...even millions of GM pickups that have their canisters at m/cyl level, located next to the radiator, yes?

Although it seems that some people don't think that an eye dropper can fill a bucket one drop at a time...

It's called evaporation?

This is an engineering concern and a fuel tank, if you notice, has been designed to eliminate that concern.

Flooded canisters was a concern back in 1983 on a carbureted F-150, it's not a concern now. You'll see more converter lockup solenoids go bad than you'll see flooded canisters due to tank topping off.

Guess what... when you top off the tank and you start the car... I know it's hard to believe, but the car is running... and your evap system will be conducting it's business with more fuel than was engineered to do so until you drive for a while!

Yeah, your gas cap and fuel tank sensor will conduct its business so you won't have to panic.

Unfortunately I actually dumbed it down so that I didn't have to actually go into the operation of the system and just plainly say that overfilling the tank can cause problems... but since you found it necessary to try and "dumb it down" further by being technical I find it necessary to correct you.

Like when you dumbed it down with your first reply (your very first posting here?) when you wrote "canister(s)?" ...you confused vacuum reserve tanks as a 2nd charcoal canister?

Again, read the full post.

Read your gas cap again...the MIL concern is about clicking the cap, Toyota doesn't seem to be spooked about tank top-off, just the gas cap's 1-click.

If you're worried about the vapors, don't. Maybe you forgot that fuel vapor from the gas tank is managed by the vehicle's PCM and Canister Purge Valve...I guess if those were defective, then vapors might be a concern...

I find this amusing since the write up was written "Yeah, we'll dumb it way down." Mythbusters uses technical procedures to either prove or disprove a theory. They don't dumb it down...

Waiting for your reply...

Waiting for your only reason to be here. Fetch.