[asmr]

I am posting this question since I believe it's of a technical nature. Request the moderators to move it to an appropriate forum if this is not the right place.

On to the issue: In the last 10 months/ 17 refills of my Taigun's petrol tank, I have faced exactly 3 instances where the pump nozzle was defective and it did not execute an auto-cutoff. In both cases, there was some spillage of petrol, obviously.

When I visit the pumps for refill, I make it a point to ask and confirm with the attendant folks whether the auto-cutoff in the nozzle is functional or not. Yet the cutoff didn't work in 3 instances where they confirmed in the affirmative and I was left arguing with the attendants as to why they said otherwise + why would I have to pay for the spillage. To no avail, of course.

So, a few questions:

1. I have read here, and elsewhere, that this filling to the brim will cause petrol (liquid) to get in to the vapor recovery (did I get that right?) system and may also impact the fuel pump functionality. Anything that I should be concerned about?
2. Is there any sort of corrective action that can be taken if in case an fill-to-brim happens?
3. Will filling the petrol to the brim cause mileage to be lower in the initial 50kms run or so? This is something I observed. Correlation is not causation but wanted to put this question to others here.
4. Is there a way to check that the auto-cutoff is working properly BEFORE they start pumping fuel in to the tank?

Thanks!
asmr

[CarNerd]

Why do you want to fill the tank to the brim? Just find out your car's tank capacity and fill around 5 - 10 litres less. Over filling is a bad idea. I found a video that explains it:

https://youtu.be/jPiiqcDxDxY

[asmr]

Originally Posted by CarNerd

Why do you want to fill the tank to the brim?

Maybe my post was not clear enough. I DON'T want to fill the tank to the brim (or top off, as said in the video you linked, very useful by the way), just until the auto-cutoff. That is different from the brim, right?

It just happened 3 times at different pumps. My questions are more on what I can do to avoid that + on whether doing that has negative impacts on the car's fuel intake system.

[narayans80]

Not cutting off at auto-cutoff is new. While I usually top-up, I've always seen the dispenser cutting off every time, petrol or diesel.

Do you supervise your car's fuelling?
Does the pump attendant lock the dispenser or manually presses and fills like in case of 2-wheelers?
Extension of above question, does the dispenser also fill for 2-wheelers?

As a general rule of thumb, never experiment with pumps. Stick to one or two at most and always supervise refueling regardless.

[cs_rajesh]

Originally Posted by asmr

Yet the cutoff didn't work in 3 instances where they confirmed in the affirmative

I have faced this in certain pumps and when I enquired with the pump attendant, he said that certain kind of "indian make" fuel dispensers fail to "auto cut off" especially when the attendant is setting the fuel filling on 1st step (that fills the fuel in slow speed). If the same fuel dispenser is set to 2nd step or 3rd step which dispenses fuel at higher speeds, then the "auto cut off" works.
By step, I mean the point where you fix the fuel dispensing or discharge flow speed.

This problem is not seen in pumps that use a "foreign make" fuel dispenser, such as what you find in Shell Fuel pumps.

[asmr]

Originally Posted by narayans80

Do you supervise your car's fuelling?
Does the pump attendant lock the dispenser or manually presses and fills like in case of 2-wheelers?
Extension of above question, does the dispenser also fill for 2-wheelers?

As a general rule of thumb, never experiment with pumps. Stick to one or two at most and always supervise refueling regardless.

I used to go to just one BPCL pump exclusively with my Santro. But after I got my Taigun, I have been experimenting with different ones in my area to see and decide which ones are reliable. I had even posted last year around December that XP95 was not available in those pumps and so I had to roam around a bit to get Speed 97 & XP100.

After reading all the stories here on Team BHP related to fuel station scams, when refueling, I am always out of the car, near the tank's hatch, watching the meter and the dispenser. That's how I was able to stop the refueling without too much spillage. Every time I have refueled, it was always with a locked dispenser. I specifically tell the attendants not to touch the dispenser once the refueling is started.

I don't think it is the same dispenser for 2 wheelers too since, except for one instance, I have filled only the super premium and/or higher octane fuels this far. Very less number of 2 wheeler go for those, but can't say for sure. But the 2 times (it was not 3, like I mentioned in my first post in this thread) this auto cutoff failure happened, both were at different IOCL outlets when filling XP95.

Originally Posted by cs_rajesh

I have faced this in certain pumps and when I enquired with the pump attendant, he said that certain kind of "indian make" fuel dispensers fail to "auto cut off" especially when the attendant is setting the fuel filling on 1st step (that fills the fuel in slow speed)... "foreign make" fuel dispenser, such as what you find in Shell Fuel pumps.

If I understood the nozzle mechanism (via YouTube University, of course), it shouldn't matter what speed the fuel is dispensed. Not saying that it can't happen at all, but I would be surprised if the engineering that went in to the dispenser was that deficient. As soon the internal sensor detects air pressure changing in the nozzle, it should cut off.

The Indian vs Foreign make thing, I am now left to wonder how do we even go about filtering the already small list of reliable petrol pumps based that criteria.

[Artyom]

Originally Posted by asmr

My questions are more on what I can do to avoid that + on whether doing that has negative impacts on the car's fuel intake system.

Something you can try is before the filling starts clearly instruct the attendant to stop at cut-off. If the issue is with the dispensing nozzle like the one you mentioned the attendant will be aware of it and will inform you in advance.At that point you can either move to a different fuel pump or change the filling kiosk at the same filling station.

[lonetraveller89]

Originally Posted by asmr

I have read here, and elsewhere, that this filling to the brim will cause petrol (liquid) to get in to the vapor recovery (did I get that right?) system and may also impact the fuel pump functionality. Anything that I should be concerned about?

Not a cause for concern if it happens just once or (in your case) twice. But if this keeps happening, there’s a risk of over-saturating or clogging up your EVAP canister. You might get a check engine light due to a faulty purge EVAP code. But the car should still run fine.

Is there any sort of corrective action that can be taken if in case an fill-to-brim happens?

Just drive? Pay attention to the fuel gauge. Driving it enough will use up the surplus fuel and evaporate/ purge the canisters. I’ve read that some models have a vapor release valve near the mouth of the fuel tank.

Will filling the petrol to the brim cause mileage to be lower in the initial 50kms run or so? This is something I observed. Correlation is not causation but wanted to put this question to others here.

Not sure about that. Filling up to the brim is usually done with the intent to squeeze out a few more kms. Hopefully somebody else can comment on this.

Is there a way to check that the auto-cutoff is working properly BEFORE they start pumping fuel in to the tank?

Well, you’re already doing all that you can by getting out to monitor the process & asking them about the nozzles in advance. In case of doubt, just fill it up to a volume that’s lesser to that which causes the auto cut-off. In this way, you can avoid overfilling and also rate the pump based on the quality of nozzles they use.

[IndigoXLGrandDi]

I have been filling Diesel in our Elite i20 Asta even after auto-cutoff ocurrs since the car was new (from Mar 2015). The car has run 2,58,000+ kms.

I am able to fill 8-10 litres of Diesel every time after the Auto-cutoff.


Am I doing wrong?

[cs_rajesh]

Originally Posted by IndigoXLGrandDi

I have been filling Diesel in our Elite i20 Asta even after auto-cutoff ocurrs since the car was new (from Mar 2015). The car has run 2,58,000+ kms.

I am able to fill 8-10 litres of Diesel every time after the Auto-cutoff.


Am I doing wrong?

I wouldn't say wrong, but manufacturers advise not to fill beyond cutoff. But you would normally think, if you can fill 8-10 liters after cut off then there is so much air space available which is excessive for normal operations and therefore, one can "top-up" after auto cut off. I do feel so and, i fill till the birm and so far have not faced problems.

My cars Elite i20 diesel and Innova Crysta Diesel.