Filling up to the brim

[Big Damo]

Due to wanting to know exactly how much fuel I'm using each time, I fill up to the top of the filler neck each time. Something happened today which I found a bit strange, and Im wondering if someone can explain.

I filled up and noticed what I presume to be some sort of breather on the left side of the filler neck right up the top.

I hang up the nozzle and notice that the level has dropped out of sight by the time I turn around to screw the cap back on.

I fill up a litte more, and thinking that there may be an air blockage in there (as I filled up with around 30% less full than my economy usually dictates) and I see fuel spewing out of the breather pipe back down into the tank. I fill up again and the same thing happens. I think I managed to squeeze another litre in, but is this normal??? Is this pipe simply a breather pipe? Why then was it spewing fuel out at me when I rocked the car??? The fuel I used was BP ultimate which virtually didn't froth at all.

What would be the best way to consistently fill up to the same level to enable accurate fuel consumption?? Should I just fill up and leave it at that the first time???

[mattz]

That's normal.
When going away on a long trip I will fill to the brim. It can take a while with the frothy diesel. but you could probably get another couple of litres in.

[biggibbo]

Perfectly normal

Once the tank is completely full, the neck fills up, the breather pipe equalises and fills up as well (gravity and all that). What you are seeing is the fuel pushing down the neck into the tank and than expelling fuel and air via the breather. Eventually the breather also fills with fuel.

[adamace]

Exelent question, To add to this who stops at first klick to leave an air gap for expansion in hot weather? what makes the fuell nossle cut out on pumps? who pins the pump handle open for long fills?

[Dunga71]

Ha ha the air gap would be there pretty quick the way my economy was before its last service

[hvac guy]

I shake the car to get out all the air.

[4wd26]

^^^ I do the same if going away on the longer trips, or if doing a calculated fuel economy run.

quickest way to confirm a full tank due to the air lock

[Sky Miner]

I try and lean my buggy to the rite a bit so there's no air trapped in the tanks
when im filling up, i got twin tanks and it take bloody ages to fill to the brim
cuz of the two filler necks joined together
Never had a problem with filling up to the brim.

[Snooozy]

I used to rock the car to fill to the brim, but since I fitted the long range tank it does not get the air lock so no need to shake anymore.

I still fill to the brim every fill as I calculate consumption each time.

As for expansion, I figure by time I get home I have used a bit over a litre & so create expansion room anyway.

[JamoGLXR]

What you are seeing is the fuel pushing down the neck into the tank and than expelling fuel

Expelled, that word is totally under used. What a great word

[Mooons]

What you are seeing is the fuel pushing down the neck into the tank and than expelling fuel

Expelled, that word is totally under used. What a great word

It used to be used a lot back when I was going to school

[Longranger1]

One about BP Ultimate diesel fuel is that it doesn't have the cappuccino effect of regular diesel meaning a proper fill takes less time.

Darned shame we can't get it here.

[salt36]

Don't know what you are talking about

Mine fills up the same every time