Help with fuel!

forgotmyname

Older metal tanks used to rust and letting the fuel get too low could cause the sediment to be dislodged when you refill.

With modern cars and plastic tanks there isnt much chance of that.

And modern filters are better designed to handle the task. Run the tank down before your next fuel filter change.

Any muck gets trapped in there and you have a nice clean tank and filter.

giraffe69

You might mistime it and run your petrol very low but given you get a warning on most moderncars(mine comes on at about 60 miles) why would you want to cut it as fine as possible? I believe running it to vapour can cause a problem with the CAT. It can certainly cause a problem with nerves.

fivetide

Paradigm wrote: »

I've been told this many, many times but still don't understand the reasoning behind it.

Surely, any "crud" at the bottom of the tank will get sucked up anyway whether the tank is 1/4, 1/2 or full 'cos that's where the fuel pickup is.

True. The previous comment is absolute guff.

5t.

Hammyman

fivetide wrote: »

True. The previous comment is absolute guff.

5t.

The crud settles in the tank. The fuel pickup is not at the bottom of the tank. What happens when the fuel gets really low is the sloshing about disperses the crud and because there isn't a lot of liquid, it mixes in really well.

The tanks petrol stations use are not made of plastic. They are made of metal. And they react the same as old metal petrol tanks do. The fuel you put into your tank is not particle free. As a lorry driver filling up a quite new wagon fitted with alloy tanks I have seen traces of black dirt on the foam of the diesel in the tank as I've been filling up. If the tank is alloy, the dirt can only come from one place. And if there isn't dirt in fuel, how come cars with plastic fuel tanks pack up from blocked filters?


So as to me talking rubbish. Next time you're at the beach try the following experiment. Get some fine wet sand and put it in a bucket - not enough sand to cover the whole bottom though, maybe 1/4 of it. Fill the bucket halfway. Tilt the bucket from side to side. You'll see the sand move slowly a bit but on the whole it will stay together. Now take out the water until there is only an inch above the sand. Now tilt the bucket from side to side as before. You will notice the sand moves far more and starts to disperse into the water....

fivetide

Hammyman wrote: »

The crud settles in the tank. The fuel pickup is not at the bottom of the tank.

If that's the case - how do you empty the tank?

5t.

Edit to add - Subaru even have a nice graphic of the thing http://drive2.subaru.com/Sum03_FuelSystem.htm

the fuel system pumps from one side to another too. I'm also sure the fuel tank cam that Top Gear used when they did the london to edinburgh and back challenge in an Audi A8 showed the fuel sloshing at the bottom of the tank.

That sloshing was the issue before I think. made for uneven pick up and knocked bits off old tanks but newer, flat tanks don't get it. Also, most modern cars have a fuel filter for exactly that reason.

here's a good post showing just what you were talking about:

http://www.bimmerforums.co.uk/forum/f18/2002-e46-318i-n42-replaced-fuel-filter-and-t98597/

If something gets in there it gets in there. Stirring up sediment is not really an issue (IMHO)

5t.

iolanthe07

Never mind the crud, running out of petrol can seriously damage the catalytic converter (according to my car handbook).

cardinalbiggles

Hammyman wrote: »

The tanks petrol stations use are not made of plastic. They are made of metal.

Guff again, most are fibreglass although they are being slowly replaced with metal tanks as fibreglass is dissolved by the higher ethanol content being added to fuels now.