Fuel gauge weirdness

The other day I popped into irving, left the car running, and filled the tank till it stopped. 13.4 gallons, IIRC. To me that says "filled up."

And yet, when I got in the car, I had just over a half filled tank according to the fuel meter. Turned the car off an on, reseated the gas cap, nothing. An hour later, it popped up a notch to three quarters of a tank.

Anyone see anything like this? Car's only got 3k so I'm not worried, it's obviously still very much in the warranty period, but what the hell?

Happened to me once as well when I left the car running. It eventually corrected itself.

You filled you it up while the vehicle was running?

i think its illegal to fill up the car while its running in canada (ontario) anyway

Yeah same here in Nova Scotia lol

Good 'ol NH..."Live Free or Die".

Besides the fact it's illegal mostly everywhere I was alway told it's not good for the car. It's a good way to get a CEL because the sensors will detect the loss of vacuum that happens with the cap on.

it's a diesel. filling it up while running is part of the fun. only an issue for gassers. did it with my 96 passat tdi all the time with zero issues. that said, i'm not surprised all the emissions crap has an issue with it, so i'll discontinue the practice with this one. it eventually (three days later) went up to a full tank. kind of fun to watch.

usualsuspektt said:

Besides the fact it's illegal mostly everywhere I was alway told it's not good for the car. It's a good way to get a CEL because the sensors will detect the loss of vacuum that happens with the cap on.

Click to expand...

My understanding is that the gas cap gets checked by the ECU if several things are met - engine warmed up and driving at 55-65 MPH for 10 minutes and the tank has to be less than 3/4 full. My Aveo had a CEL for gas cap and it finally went on after a 12 minute freeway trip. Screwed cap on and went out after another 12 minute freeway trip. That being said I still don't fill up my gas cars while running.

If I am at a gas station I don't leave the diesel cars running while filling up for fear of gas fumes getting sucked into my engine - however, that is probably not probable I still don't risk it.

you're diesel vw isn't an aveo, nice to compare the two though

I wasn't comparing. I was explaining how the tank check works on a gas car. Just used my gasser as an example of how it works. Also, maybe I shouldn't say my understanding - I should have been more concrete. Those ARE the parameters of when the tank gets checked by ECU.

yes, those are concrete things for your aveo's ECU, yet they don't apply to you're TDI's ECU, and I didn't see where you were stating the difference.

It is not Aveo specific but gas car specific. I am sure there are differences when there is a specific gas cap light - but I have a feeling the same parameters apply.

Anyways, way off topic - I shouldn't have even brought gasoline into the mix.

I would like to find out how it works on the TDI since it does have a fuel cap light in dash. Maybe when I get to 3/4 tank I'll loosen cap and see what happens.