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Discussion Starter #1
Anyone have this issue? It started 3 fillups ago - usually when I fill up the car, the tank goes all the way pretty much above the Full Line. Starting the last 3 fill ups, it's a tick under - probably 1-1.5 gallons short of where it used to fill to. No changes made. Any ideas?
 

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Does the situation mean that you can't get any more fuel into the gas tank even though it should hold more? How do you know that it should be possible to get more fuel into the tank - from the dash fuel gauge? Is it that the filler nozzle shuts off before the tank is full when I did not do so previously? Does the gas already in the tank foam and bubble up into the filler neck and cause the filling nozzle to switch off? Or are you going by how many miles you can get from a tank of gas before the low fuel light switches on?

So far with mine nothing has changed since it was new. When the filler nozzle switches off my dash fuel gauge reads Full. It is possible to get s small amount more into the tank after the first nozzle switch off occurs, but that is rather minimal.
 

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Does the situation mean that you can't get any more fuel into the gas tank even though it should hold more? How do you know that it should be possible to get more fuel into the tank - from the dash fuel gauge? Is it that the filler nozzle shuts off before the tank is full when I did not do so previously? Does the gas already in the tank foam and bubble up into the filler neck and cause the filling nozzle to switch off? Or are you going by how many miles you can get from a tank of gas before the low fuel light switches on?

So far with mine nothing has changed since it was new. When the filler nozzle switches off my dash fuel gauge reads Full. It is possible to get s small amount more into the tank after the first nozzle switch off occurs, but that is rather minimal.
this is the first i've ever seen on any of the cars i've owned (9 so far).

i could probably get more fuel in if i tried but i avoid filling more after the hose clicks when i can.

i do not "know" whether it is possible or not, i just know that it's turning off early for each of the last 3 times. i tried restarting the fillup the last time, only went 0.3 gal before clicking off again.

i don't fill up consistently when a light comes on or something, it is more opportunistic in nature. the driving also varies greatly, so obviously it is not based on mileage. here is my fuelly if you want more details about driving: Rav4 V6 (Toyota RAV4) | Fuelly

as far as the fillups, again the only difference is, i fill up, and the needle doesn't go all the way beyond full like it used to. i do not believe it is some kind of user error. perhaps it is filling up all the way, and the needle just doesn't go up to where it used to. or it is not filling up like it used to - hard to say?


: that said, if it were actually filling up normal and the gauge was messed up, the gauge would go down slower - but it does not, it goes down as if it were where it was.
 

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Do you hold the pump lever or out it in "hands free" mode. Next time try hands free and put it on the 2nd to last click. Do you have a check engine light?
 

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Seems to me the only way to get a consistent reading is to wait until the low fuel light comes on and then fill up the same way each time. Our pumps in RI have their automatic latches disabled, maybe by law, so you have to hold the handle the whole time. I hold it all the way in until it clicks off a couple of times and then pull it partially out and click it several more times, often getting almost another gallon in.

On my Accord I reset the A odometer when the light comes on and then drive another 30-50 miles before refueling. One time recently I kept on clicking until I got in one gallon more than the tank is supposed to hold! (And yes I know that's supposedly an expensive & disastrous scenario.)
 

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this is the first i've ever seen on any of the cars i've owned (9 so far).

i could probably get more fuel in if i tried but i avoid filling more after the hose clicks when i can.

i do not "know" whether it is possible or not, i just know that it's turning off early for each of the last 3 times. i tried restarting the fillup the last time, only went 0.3 gal before clicking off again.

i don't fill up consistently when a light comes on or something, it is more opportunistic in nature. the driving also varies greatly, so obviously it is not based on mileage. here is my fuelly if you want more details about driving: Rav4 V6 (Toyota RAV4) | Fuelly

as far as the fillups, again the only difference is, i fill up, and the needle doesn't go all the way beyond full like it used to. i do not believe it is some kind of user error. perhaps it is filling up all the way, and the needle just doesn't go up to where it used to. or it is not filling up like it used to - hard to say?


: that said, if it were actually filling up normal and the gauge was messed up, the gauge would go down slower - but it does not, it goes down as if it were where it was.
Interesting that when you last reported trying to add fuel to the tank after the filler nozzle had switched off you were able to get 0.3 gallons more into the tank. With my RAV, the amount which can be added after nozzle switch-off is much less.

Checking your Fuelly mileage, it doesn't vary significantly. Do you always use the same brand of gas? Does the situation occur if you use a different brand of gas, or if you always use the same brand and go to the same gas station and use a different pump each time? Or do you always use the same brand of gasoline, the same station, and the same pump as much as you can? As you mentioned the apparent problem is unusual since you haven't experienced it with your other vehicles, and neither have I with my other vehicles.
 

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Discussion Starter #7
Interesting that when you last reported trying to add fuel to the tank after the filler nozzle had switched off you were able to get 0.3 gallons more into the tank. With my RAV, the amount which can be added after nozzle switch-off is much less.

Checking your Fuelly mileage, it doesn't vary significantly. Do you always use the same brand of gas? Does the situation occur if you use a different brand of gas, or if you always use the same brand and go to the same gas station and use a different pump each time? Or do you always use the same brand of gasoline, the same station, and the same pump as much as you can? As you mentioned the apparent problem is unusual since you haven't experienced it with your other vehicles, and neither have I with my other vehicles.


Almost always the same brand, sometimes Shell but mostly BP. Same station & same pump. Of the "low fills," 2 of the 3 were at the same station and pump I always use.


Oddly enough though, I filled up yesterday and it went back to all the way full, after 3 consecutive fillups. The same BP pump, no changes. Well, one change - I "shook" myself inside the car early on as the car was filling up, just to make sure everything was level. Filled up like normal all the way up though, so I guess it's all good now..
 

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Discussion Starter #8
bumping this - after one time of going back "all the way" full, above F, the car has again been only filling up to slightly below F. The fuel gauge starts to drop as soon as you start driving after that, whereas before, it hovered above F until like 40-50 mi or so, at which point it starts going down (as most cars do).




Any ideas on this? Definitely odd and it's underfilling by at least 1 gallon, if not 2, which is frustrating to say the least.


A few ideas:


1) gas tank breather tube/vent tube clogged
2) refueling control valve to evap canister (may be the same thing?)
3) charcoal/evap canister itself (?)
 

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Discussion Starter #9
 

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With the information provided so far, we can't tell if your tank is holding less that it did before, or your gauge doesn't rise as high as before.

STEP #1
If your tank hasn't been made any smaller as the result of a collision or backing over a rock which dented the tank, then it's a safe conclusion the tank has the same capacity that it always did.

STEP #2
It may be possible that the pump shuts off early due to the way you hold the nozzle, or the pressure and flow rate from the pump. So at least one time you need to top off the tank ( after the auto shutoff) to ensure the tank is really filled to capacity. Since you did that already, and it resulted in a very small amount of extra fuel being added, I think it is safe to assume the tank is being filled to it's factory capacity of 15.9 gallons.

STEP #3
So that narrows down your complaint to "the gas gauge is dropping quicker than it did before".

Maybe it really is dropping faster due to an engine problem burning fuel faster. Simply calculating your fuel economy with a calculator Miles/gallons will show if the fuel really is being burned quicker. This calculation is not dependent on having a working gauge at all.

If your fuel economy is normal then it looks like the gauge has changed it's characteristics. You have already raised the question "why doesn't the needle go as high as it did before, and why does it drop faster". The answer to that question is not important. The correct question is your gauge reading accurately now, and will it prevent you from running out of fuel.

I suggest that you drive until the low fuel warning comes on and then refuel. The tank has a 15.9 gallon capacity and the light should come on with about 10%-15% remaining (1.6 to 2.4 gallons). When you fill your tank, make note of how much fuel it will take. If it takes 13.5-14.3 gallons then your gauge is accurate and you can rest assured you will be warned before running out of fuel. You just need to stop worrying about the way things used to be.

If you run out of fuel before the light comes on, or you have a larger reserve than 13.5-14.3 gallons, then your gauge is faulty.

TLDR
1)Your tank IS being filled to the full capacity of 15.9 gallons
2) Your engine may be burning fuel faster than before. This is easily proven with a calculator.
3) Your gauge is inaccurate. Easily proven by checking how much fuel can be added after warning light comes on.

Any ideas on this? Definitely odd and it's underfilling by at least 1 gallon, if not 2, which is frustrating to say the least.
I don't know how you determined this by looking at your gauge!!!!!!!
 

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Discussion Starter #11
thanks for the detailed post. it doesn't have to be either the tank is physically smaller or the gauge is off/doesn't rise like it used to - the 3rd, subtle option is that the tank is not filling as much as it physically used to.


I am more detail oriented than most, so I appreciate your points and will address step by step:


1) no physical damage to the tank, though that theoretically should not change where the gauge is unless the floater was somehow impacted by the damage - unlikely since it is at the top somewhere. If the tank were damaged, the gauge should still go to where it used to (above F), but physically take less gas. Regardless, no physical damage.


2) I always let the pump go by itself, whichever station I'm at. always make sure the pump's hose is not tangled/not resisting the position it's in when it goes into the tank. I almost always use the same station, and same pump itself. I've tried different pumps since this began, however. The assumption you make (safe to assume the tank is being filled to it's factory capacity of 15.9 gallons) is not necessarily true. The basis of my discussion is trying to find out reasons why that assumption may NOT be true - for example, what I'm looking into at the moment, which is a clogged evap hose line.


3) Fuel consumption has stayed the same, as measured by my Fuelly. Rav4 V6 (Toyota RAV4) | Fuelly Obviously it varies based on the kind of driving I do, but on the whole it has been performing as normal. From my previous tracking, historically my car hits the Empty LIGHT at 12.5 gallons used. It hits the Empty LINE (at my eye/line of sight) at 13.5. The total tank is 15.9, and I usually fill up anywhere from 10 to 14 gallons, usually somewhere in the middle. My comment on the gauge "falling faster" wasn't an clear statement on my part - it is falling at the same pace, but starting from a different spot. Right after you fill, normally, the gauge on most cars is above the F line, and doesn't start moving until about 1.5 gallons used. This is true for my Corolla, Mini, Evo, parent's Outback & Camry, and used to be true for the Rav4. Once it starts moving however, it moves at a regular pace, relative to your consumption. For my Rav4 now, instead of starting above the F and staying until 1.5 gallons used, it starts decreasing right away. It is decreasing at the same pace, just starting from a different spot. Hope that was a little clearer.


I'll fill up as soon as the light comes on and see how far it is from 12.5. If it's significant, then I should expect for whatever reason that the tank physically isn't being filled as much as it used to. #1 suspect at this point is the evap canister hose perhaps being partially clogged - one way to potentially test this also is to fill up at the hose's slowest fill setting, which gives more time for things to vent and the gas level to settle/be less volatile. I mentioned one instance in the midst of this where the fuel gauge did actually go up to where it normally did - and I did do something differently at that time - I physically shook the car as the gas was filling. I am still assuming that was random/insignificant, but I may try again and see if the result is the same.


Finally, I am getting a notion, rightly or wrongly, of a slightly patronizing tone - not necessarily from RickL, but in general, regarding this matter. Obviously most internet Joe's are not well-versed in how car mechanics work, and while I can't rebuild an engine, I do the maintenance on all 4 of my cars and race 2 of them nearly every weekend during the season. I am extremely detail oriented and keep track of all the stats, trends, behaviors, noises, etc. on all my cars. My point is, I'm not an idiot, I pay attention, and when I say the gauge isn't rising to what it used to after a fill-up, it is doing exactly that. The behavior is abnormal to how it used to fill up. There should be a reason/cause for the change, as well as a fix/solution. Cars don't just randomly behave differently without a specific cause.
 

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Discussion Starter #12
and I determined it is underfilling by 1-2 gallons because in the past, the fuel gauge went past F after a fill up, and did not move until about 40-50 miles (1-2 gallons burned off, then floater starts to move where the gauge reads normally). Now, it fills under the F line, and moves right away after driving. Jeez, is this really that difficult to understand? Or are you guys not paying attention to your gauges?


If I were filling the same amount of fuel as before, but the gauge was simply staying under the F line (for some unknown reason), then the gauge would decrease at a slower pace, because there is more fuel being consumed in a smaller area on the gauge.


i.e., next time you fill - you should notice, as I have with ALL my cars, that the tank is filled past what the gauge considers "full," i.e., above the "F" line. The needle on the fuel gauge won't actually move until after you've burned off about 1-2 gallons of gas. Let's stop and confirm there - this is true for nearly all cars I've driven, including the Rav4 prior to this issue.


Next, try filling the tank 2 gallons short of where you think it should be. It will be somewhere under F. From that spot, it doesn't sit until 1-2 gallons of gas have been burnt off - it decreases as it normally would, because the floater is in a spot the gauge reads regularly.


In other words, if you filled up, got in the car and started it, and saw that the fuel gauge was sitting at only 3/4ths full, wouldn't you roughly know the car was underfilled by about 4-6 gallons? In a similar way, I know my car is underfilled by 1-2 gallons. Yes, it assumes that the gauge reads correctly. However, 1) that is a fairly safe assumption to make (gauges rarely fail half way), and 2) there are other signs the gauge is reading correctly, such as the rate at which it decreases as fuel is consumed. I will do further testing based on past consumption history and how much the car fills up at certain points on the gauge, to verify.

Let me know if I'm not being clear in any of this.
 

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Quit trying to fool the pump switch-off.
Over-filling can mess-up your evac system.
.
 

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Discussion Starter #14
Quit trying to fool the pump switch-off.
Over-filling can mess-up your evac system.
.


when did I try to fool the pump switch-off? I'm trying to find out why the pump switch-off is happening early, not overfill & soak the charcoal. Unless you are referring to me shaking the car - I did that mid fill, not as it was going to the top. I never restart the pump after it's finished, except in very rare circumstances, such as this past once, trying to find out why the tank is not being filled all the way
 

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From the video it appears that there are some gasoline vapor-loving wasps in the U.S. South! Ordinarily I would have expected that they would be repelled. How did they manage to get into the plumbing?


Let's hope that your partial gasoline filling problem is so easily resolved!
 

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From the video it appears that there are some gasoline vapor-loving wasps in the U.S. South! Ordinarily I would have expected that they would be repelled. How did they manage to get into the plumbing?


Let's hope that your partial gasoline filling problem is so easily resolved!


I believe that is an open ended tube for venting. I'll take a look if I get a chance over the weekend. I'm not totally familiar with the system in general, but given the way pumps work, something is causing the pump to think the tank is full when it isn't. The closest thing I've found related to that is clogging/issues with the vent hose and/or charcoal canister. More likely the former, an issue with the latter would throw a CEL
 

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From the video it appears that there are some gasoline vapor-loving wasps in the U.S. South! Ordinarily I would have expected that they would be repelled. How did they manage to get into the plumbing?
Yeah, when I watched the video and he pulled that open-ended hose out, I said "dirt daubers!" because I have seen their work many times before. One time I grabbed my cheater pipe from the garage only to find it plugged up with dirt on both ends!!
 

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Yeah, when I watched the video and he pulled that open-ended hose out, I said "dirt daubers!" because I have seen their work many times before. One time I grabbed my cheater pipe from the garage only to find it plugged up with dirt on both ends!!

Well, with all of that I'm glad that I don't live in the South! Here, daubers confine their mischief to building mud nests under house eaves. But I would like to have your much less expensive gasoline and diesel! :wink
 

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Finally, I am getting a notion, rightly or wrongly, of a slightly patronizing tone - not necessarily from RickL, but in general, regarding this matter. Obviously most internet Joe's are not well-versed in how car mechanics work, and while I can't rebuild an engine, I do the maintenance on all 4 of my cars and race 2 of them .
I apologize if I gave you that impression. Rest assured that I did not spend 20 minutes typing up a list of items for you to consider, just to make you look stupid. Since I don't race either of my cars on a track, I guess I could be considered an Internet Joe, although I do perform maintenance on each of them.

In an effort to help explain what might be causing your recent problems I provided a list of items, which were all legitimate reasons or questions, that would help explain what you are experiencing. After seeing the video you posted it became a little more clear to me what possible cause you have been primarily focusing on.

In this first diagram (sorry about the quality) it is easy to see how the tank would not be filled to maximum if the flow through the canister was restricted.



In the 2nd diagram (taken right from the RAV4 service manual) you can see that a blocked vent to the canister should not stop the tank from filling. The air pressure should be relieved through the hose that runs from the topmost area of the tank, to the opening of the filler neck. As long as the pump nozzle is not placed in a position to block this vent!.



So this is just another thing to consider, along with my earlier list of considerations. (if you care to entertain the possibilities).

The diagram also raises the question "How can the canister be damaged by overfilling?" The diagram shows the presence of both a "float valve" and a "fuel cutoff valve" which should prevent liquid gas from getting into the canister. There does appear to be a "canister filter", but that appears to be outside the "filler tube", and permanently exposed to the atmosphere. I suspect the filter is part of the leak detection system.
 
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