Biggest ever fill up?

[volvorocks]

Originally Posted by I-S

What's the most you've ever got into the 70 litre tank of the V70/S80?

I got 72.27 litres, costing £104 in the other day...

Mine was similar around the £104/5 mark. Also got in around £140 once when the strike was on - ONLY due to necessity when the prices went to £9 a gallon plus in certain areas due to shortage.

Regards

[tt82]

Mine was 66.67 Litres!

[Macabre]

Out of interest, what is the ideal number of litres to keep in the tank all the time? I routinely will fill up when the red light comes on. Is this taking it too far? The time before last I filled up with 67 litres before it clicked, so it was pretty much empty. Usually the trip computer says 80 miles left when the light comes on.

[tt82]

I always try and fill up at the 1/4 mark on the fuel guage. Generally this means putting about 60 Litres in. As others have said, this stops all the dirt being sucked through and also helps the fuel act as a coolant to the fuel pump.

[Rettopian]

Take your point entirely about sediment, water, condensation etc. They certainly exist and will be in most fuel tanks.

However - I remain sceptical - not about how harmful it is if it gets to those important little places, but how often it happens to get there in reality. Yes - there will be sediment & water - inevitable - but that's why the fuel filter & its associated water trap are there to deal with isn't it? If there's that much sediment surely the filter will simply clog up & prevent stuff getting to the pump in the first place?

Also whenever we fill up a consequence must be that we'll stir up all that lovely sediment/rust/water then just drive off, thereby increasing the chances of it getting sucked into fuel lines etc. We don't sit there at the pump for two hours waiting for everything to settle.

I think (hope?!) we get can get a bit paranoid about things from time to time.

[MartinK]

My best is 70.86 litres. That was when the car had done under 10,000 miles (I was getting ~37mpg).

As the vehicle's got older, MPG has improved as well.

As above, I tend to re-fill early. Most of my miles are on the M6, M74 & A9, and fuel stops on these roads can all be expensive, so I fill up on Shell/BP near home to make sure I have enough for the journey.

I do see an improvement in MPG when using BP Ultimate or Shell VPower..

[clivea]

Originally Posted by GrantA

There is a danger in "emptying" your tank as the last dregs will slosh about in the tank and stir up the sediment which in turn will pass through your fuel pump and or the fuel filter. Apart from blocking the filter prematurely some fuel pumps depend on the fuel passing through the pump to keep them cool, if the fuel is laden with sediment it will not do the pump any good and could, in extreme cases, cause the fuel pump to overheat with catastrophic results.

I know you said you have done over 300k miles and on each car you have emptied the tank routinely before filling it to the brim, all I can say is you have been very lucky not to have had any problems. If fuel lies in a tank for any period of time condensation will form as the temperature changes especially in the UK. You also cannot guarantee that the petrol or diesel that you are getting when you fill up is totally condensation and sediment free. Water is heavier than petrol and diesel so that condensation (water) will drop to the bottom of the tank and cause some corrosion unless the fuel tank is lined or made of a non-ferrous material. The corrosion will continue to occur and mix with the sediment already there until the fuel tank is cleaned out. This corrosion, if allowed to get really bad, will destroy a fuel pump whether diesel or petrol. In the Military we used to have a routine to drain off any water and sediment from the fuel filter and if you have water in the filter then it is also in the fuel tank.

But don't take my word for it ask any Mechanic or Technician or even go on the Internet and Google "should I let my fuel tank empty before filling up?". Lastly if you ever completely run out of fuel good luck with trying to prime the fuel system on a modern car.........

Your right on this one. When I lived in Canada we routinely dosed the fuel with an additive during winter in order to take out any water. However the engines were petrol. Think it was ethanol that we used.

[GrantA]

Originally Posted by Rettopian

Take your point entirely about sediment, water, condensation etc. They certainly exist and will be in most fuel tanks.

However - I remain sceptical - not about how harmful it is if it gets to those important little places, but how often it happens to get there in reality. Yes - there will be sediment & water - inevitable - but that's why the fuel filter & its associated water trap are there to deal with isn't it? If there's that much sediment surely the filter will simply clog up & prevent stuff getting to the pump in the first place?

Also whenever we fill up a consequence must be that we'll stir up all that lovely sediment/rust/water then just drive off, thereby increasing the chances of it getting sucked into fuel lines etc. We don't sit there at the pump for two hours waiting for everything to settle.

I think (hope?!) we get can get a bit paranoid about things from time to time.

Many fuel pumps are fitted into the fuel tank, I believe that is the case with most Volvos but I stand to be corrected. If your fuel pump is fitted into the tank it will not have the benefit of the filter stopping the crud/sediment/whatever passing through it so there is nothing to prevent the pump getting damaged although I do admit it appears to be a rare occurrence these days. Even my 36 year old Porsche had the fuel pump directly connected to the tank at the front and the filter was in the back, the advice with the Porsche was "never let the fuel level get so low as to allow the pump to lose suction as the fuel cools the pump as it passes through". The other point about letting your fuel tank "empty" before filling it up is there is a possibility of introducing air into the fuel system, yes it may self prime but why take the risk, let the tank empty once to see what it holds by all means but, like others I never let my tank drop below ¼.

[Rettopian]

So if they put the pump in the tank, presumably the pickups will be at the bottom of the tank too?

I can't imagine the idea of crud being sucked into the think would have escaped notice - so what engineering solution have they put in place to prevent ingestion of sediments etc.?

[GrantA]

Originally Posted by Rettopian

So if they put the pump in the tank, presumably the pickups will be at the bottom of the tank too?

I can't imagine the idea of crud being sucked into the think would have escaped notice - so what engineering solution have they put in place to prevent ingestion of sediments etc.?

I have no idea what specific vehicles have fitted but I do believe there is normally a coarse filter at the bottom of the tank/pump and this "filters" out the larger sediment particles, the rest passes through the pump to the fuel filter. So the pump will be subjected to sediment passing through it especially if the stuff in the bottom of the tank is stirred up. As the filter on the bottom of the pump is normally only a plastic screed type filter any sediment trapped there will most likely drop back into the tank when the engine is switched off.

I also believe that petrol/diesel delivery pumps (in garages) have a system of filters to ensure that the fuel you get from the pump will be as clean as they can make it. However, as I said before, if you have a metal (steel) fuel tank and there is any moisture at the bottom of the tank rusting will occur, it may not be evident for years but it will be there.

Fuel filters are fitted into vehicles to prevent sediment (dirt) getting into the engine fuel injection system which has very fine clearance and could be damaged without the filtering process.