Did I overfill the gas tank?

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George7941

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My truck has a 34 US gallon/ 128.7l tank. I filled it up yesterday and it took 129.7l before the station filler nozzle shut off (the first time).

I had eased up on the nozzle trigger towards the end and was pumping at about a litre every 8 seconds. Would this low flow have caused the nozzle not to shut off normally?

I had only gone about a hundred kms after the LO fuel light came on and I have gone over 150 kms after LO previously, thus I have reason to think the tank was not totally empty.
 
I agree with the pump lied theory.

It's not in the best financial interest of the gas station to have their pumps calibrated to be generous.

You caught them this time....don't use that pump any more!
 
A few years ago, I swear I am not making this up, there was a news clip about some station where they had software that would keep the pump accurate at specific intervals such as 1, 2, 2.5, 3, 5, and 10 gallons, but if you purchased other amounts it would short you. The ides was to look clean to any one testing the accuracy of the pump, but still cheat the people when it could for bigger profit.

Computers are a tool. And like any other tools, they can be used for good or bad things.
 
My Subie has a 16.9 gal tank, but the fuel gage needs to be pegged low to get anywhere close to that. I normally fill'er up as soon as the light comes on at ~ 1/8 tank, and never have to add more than 13 gal. Even when right on E (which I'm more inclined to do on a long road trip,) the most I've added is a little over 15 gal.

So, how much do YOU normally add for the condition you listed? Every gage is different, so there's really no way for us to tell you whether or not you over-filled. One sure fire sign that you did, is overflowing - it seems obvious, but a normal fillup includes filling the tank completely and a portion of the filler neck, so too much more would be quickly noticed.
 
Pump issue seems most likely.

I've never come close to max capacity when filling. If I got within 1 gal of capacity during fueling, that meant I went a looong time with the light on. They like to give people a reserve.

e.g. - Sister's 4runner states 18.5g capacity. Road trip, running with light on, gauge BELOW E for a bit - took 16.7g. Brother and Dad thought we were pushing it too far, I almost bet them it would stop by 16.5 - I would have barely lost.
 
I always fill up at this large Canadian Tire gas station because it is close to my house and I have a Canadian Tire credit card that gives me 10c off a litre. With the large gas tank I seldom find myself running low on gas on the road. I think it is a corporately owned store, so there is less incentive for any one individual to shortchange the customers.

Under similar circumstances my truck has always taken about 120 to 122 litres at the same station, judging by how far I drove after the LO fuel light came on.

Perhaps this one time this pump was out of calibration. I will certainly be keeping a close watch on my fillups.
 
Originally Posted By: gathermewool
One sure fire sign that you did, is overflowing - it seems obvious, but a normal fillup includes filling the tank completely and a portion of the filler neck, so too much more would be quickly noticed.


It isn't that obvious to me. On the diesel trucks I work on the filler neck is on the side of the tank and, by design, the tank cannot be filled up 100%. There is air space left at the top to take care of expansion in volume due to temperature changes. Perhaps light duty tanks will also have the air space on top, even when the filler neck is full.
 
Originally Posted By: zerosoma
I always pump a little extra gas in to the nearest dollar. I wouldn't sweat it man.


It is nothing to sweat about but his issue is why did the pump stop at 1L more than the stated capacity according to the manufacturer.

My guess is it's a calibration issue. I would suggest using another pump for the next fill up.
 
Originally Posted By: zerosoma
I always pump a little extra gas in to the nearest dollar. I wouldn't sweat it man.

Doesn't this foul the charcoal canister over time, if you're really overfilling and the excess fuel gets dumped in the canister?
 
Last edited:
Originally Posted By: Towncivilian

Doesn't this foul the charcoal canister over time, if you're really overfilling and the excess fuel gets dumped in the canister?


The rule is that when the nozzle "clicks off" automatically you SHOULD NOT ATTEMPT TO ADD MORE GAS.

You are correct with many vehicles you will get raw gas into the charcoal canister and once it is contaminated it cannot be reversed the only solution is to replace it and the cost of replacement canisters is expensive for most models and also result in a check engine light that will cause you to fail emissions tests.
 
Originally Posted By: antiqueshell
Originally Posted By: Towncivilian

Doesn't this foul the charcoal canister over time, if you're really overfilling and the excess fuel gets dumped in the canister?


The rule is that when the nozzle "clicks off" automatically you SHOULD NOT ATTEMPT TO ADD MORE GAS.

You are correct with many vehicles you will get raw gas into the charcoal canister and once it is contaminated it cannot be reversed the only solution is to replace it and the cost of replacement canisters is expensive for most models and also result in a check engine light that will cause you to fail emissions tests.
Thanks!
 
Originally Posted By: George7941
...I had eased up on the nozzle trigger towards the end and was pumping at about a litre every 8 seconds. Would this low flow have caused the nozzle not to shut off normally?...


Yes, I worked at a service station a long time ago, so I'm familiar with how the dispensing nozzles behave. I don't believe the auto-shutoff mechanism has changed substantially over the years. If you reduce the flow to a very low rate, the auto-shutoff doesn't activate, and in fact you can pump gas until it just overflows the fill on the car.
 
Ok, from now on I will just ease up a bit towards the end of the fillup and not ease up too much. The miles I get from this fillup might tell me if in fact I overfilled.
 
Originally Posted By: George7941
Ok, from now on I will just ease up a bit towards the end of the fillup and not ease up too much. The miles I get from this fillup might tell me if in fact I overfilled.


No need to "ease up" when filling up at all. The auto shut off on the nozzle is designed with users keeping the gas flow high. Or if you have the option in your area to keep the pump operating with out having your hand on it, select a detent on the nozzle handle and let it be until it shuts off automatically.
 
Unless you like getting evaporative emission CEL like O0440 or P0446 etc later in the life of the car, stop trying to get the last gallon of gas in the tank.
 
I wasn't trying to squeeze in extra gas into the tank because I know that can hurt the evaporative emissions system. I merely eased up on the trigger to prevent splashback. I always stop when the nozzle clicks off the first time.
 
Originally Posted By: JimPghPA
Computers are a tool. And like any other tools, they can be used for good or bad things.



LOL! PEOPLE are tools. That is all.
 
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