How low do you go before refuelling?

[Dan_C]

Normally I refuel when its 1/4 tank, with my new Fiesta though its been lower than the 1/4 gauge on the dash, is it bad to wait til the warning light comes on to refuel?

And how many of you refuel to the top? Usually I put in enough to take it to 3/4 tank if doing a lot of driving. If not enough for 1/2 tank full.

[cjay1]

I let it go into the red and at around 30 miles to empty I refill to the top. why refill more than you have to? 

[Luke4efc]

Unless you're always getting stuck in lots of traffic and don't want to get into the red area.

These people who think it sucks up more dirt from the bottom of the tank makes me laugh. How do you think the fuel is sucked up by the pump anyway? I'll give you a clue, it's certainly not the top otherwise the last few litres would never get used.

I go from fuel light to brim tank each time. Only time I could think of not to do that is if you're not planning to use it all within 2 months or so.

[Zico]

I mostly fill the tank the day after the fuel warning light comes on (easier for me to get to the Shell garage on the way into work than on the way home). If I'm close to empty I will put in £5 at the nearest garage to get home and then fill up the next day at Shell.

[Ad@m]

Usually when the light comes on. Depending on what I need the car for, I may fill till the pump goes click or put about 10L if I am not using the car much.

 

[wilto]

I refueled this morning with 12 miles left to go.

I've always refueled like this since I started driving 30 odd years ago, never had a problem and never run out of fuel. I don't think in all that time I've filled my tank to the brim more than a handful of times. It always £10 here, £20 there, ect.

If I'm planning on a long journey I calculated the milage and work out roughly how much fuel I'll use and put in that amount plus an extra fiver or tener. 

Don't know why I'm like this, it's just what I've done since starting to drive. As Luke said I've NEVER had a problem.

53 minutes ago, Luke4efc said:

These people who think it sucks up more dirt from the bottom of the tank makes me laugh. How do you think the fuel is sucked up by the pump anyway? I'll give you a clue, it's certainly not the top otherwise the last few litres would never get used

 

[Stoney871]

Usually at 1/4 tank but will occasionally go to the warning light which on my car leaves approximately 50 miles to empty.

[jace1969]

Mainly when on like a few on here a 1/4 of a tank,no reason just always done it.

[Titanium]

Usually wait until fuel light shows approx 50 miles to go before filling up unless preparation for a long journey or my Tesco 10p off a litre date is about to expire.

[dansallis]

I'm the odd one out then... I fill my car up just as the clock is about to hit 0mi to go! 

Probably a bit risky, but have been doing this 7 years and only run out once (in the middle of the Dales!). 

My commute is pretty routine though, 30 miles each way, almost exactly the same driving speeds and traffic every day (because of the time I drive).

[iantt]

i fill when on 0 miles left also , then im ok for at least 3 weeks commute

[Bobr]

I fill up as soon as the car tells me I'm low.   Can't see any reason to run out of fuel.

[Phil21185]

10 hours ago, Luke4efc said:

 

These people who think it sucks up more dirt from the bottom of the tank makes me laugh. How do you think the fuel is sucked up by the pump anyway? I'll give you a clue, it's certainly not the top otherwise the last few litres would never get used.

That may be the case, but the crap in the tank is heavier than the fuel and will sit on the bottom of the tank.

If you are pumping fuel which is in a tank of say, 95% fuel and 5% sediment, ie a nearly full tank, the chance of sediment to fuel 'sucked up' is obviously much lower.

When nearly empty, that ratio of sediment to fuel in the tank goes up, so the chance of sediment entering the fuel system also increases.

Could it also be that fuel splashing down into an empty tank on top of any crap that's there will stir it up into the fuel more than if there's some fuel already in there?

I encourage you to take the fuel filter off your car and replace it with a section of straight-through pipe and see what happens 

I've just had to have the filter on mine changed after loss of power and a low fuel pressure warning code. What happened earlier that day? I ran the tank down to 20 miles to go before filling up.

Co-inkydink?

[TomsFocus]

I let mine run down into the red every time and then brim it.  Try not to let it get below the 25 miles marker but if it's a couple of days until I get paid then it happens occasionally.

There isn't any sediment in modern fuel tanks, they're plastic not metal, I've broken several cars for parts and always removed as much fuel as possible from the tanks because I'm that tight.  Even at 12 years and 100k there's just a very thin layer of dirt, more like dust, not even half a mm thick.  Obviously you don't want that in the injectors, and that's why the filter is there, but it's not like you'll suddenly suck half a beach into the fuel lines by running it a bit low.

In your case Phil, you probably sucked some air into the fuel lines.  Or had water in the fuel which was floating on top of the diesel for months.  I seriously doubt it was caused by dirt.

[alexp999]

Only thing I've noticed letting it run right down is that there is a pressure difference (vacuum in the tank I assume?), which can trip the nozzle sensor.

I have to partly insert the nozzle just enough to engage the easy fuel valve and let the air in (or out?) before I can fill up.

I tend to fill up once I'm around 1/8th of a tank, though often forget until the light comes on and it bongs at me. Only once did I get down to 3 miles as I wanted to fill up at a cheaper station I knew I'd be passing.

Also FWIW, if you're the sort of person who only tops up £10 a time (like my Mum, why?), if its really low and you don't put a lot in, it can fail to register. She had this on a 206 and her current Kuga.

I personally dislike filling up, so always fill the car to make it longer between visits.

[Bobr]

I always brim the tank as it gives me a good indication of MPG.

[Crafty14]

I was told it puts more strain on the fuel pump the lower the fuel amount - so always being in the red was bad for the pump. Not sure how much truth is in that - but I always stay above a 1/3 tank anyways.

[MJNewton]

11 hours ago, Phil21185 said:

[...]

Could it also be that fuel splashing down into an empty tank on top of any crap that's there will stir it up into the fuel more than if there's some fuel already in there?

[...]

I can understand the logic behind your theory but I don't think it manifests itself like that in practice. Here's the fuel pump, and most importantly the in-tank pre-filter,  pictured straight after being pulled from my Hyundai Coupe having covered 160k miles over 13 years:

That's a really fine mesh so with modern fuels and plastic tanks there's evidently nothing really to pick up. Note that I *always* ran the tank to nearly empty as I was obsessed with keeping mpg records and wanted to minimise calculation errors wherever possible.

 

[Phil21185]

Interesting. 

Why is there a need to change fuel filters then? They must pick up something and at least in my case, changing it cured my problem...

 

[iantt]

Interesting. 
Why is there a need to change fuel filters then? They must pick up something and at least in my case, changing it cured my problem...
 

Or put itv another way, why is there no inline fuel filters on most petrol cars now?

[Phil21185]

Huh. So is it just diesel that tends to be bitty?

 

[iantt]

It's the injectors that need no bits. Latest gen diesel injectors have holes down to 5 microns I'm told and filters need to filter down to 2 microns. That's small!!!

[Phil21185]

So is it possible to drag rubbish through from running too low in a diesel?

[Phil21185]

1 minute ago, iantt said:

It's the injectors that need no bits. Latest gen diesel injectors have holes down to 5 microns I'm told and filters need to filter down to 2 microns. That's small!!!

So my wife tells me...

[iantt]

In theory the fuel filter should stop any dirt getting to pump and injectors. That's why quite often fuel filters become prematurely blocked requiring change at earlier intervals.