How many miles left on "empty"?

[Chilli1]

Has anyone ever measured the number of miles left when the fuel gauge ticks over to empty with a 1.2 HTP?

 

I'm trying to almost empty the tank... almost!

[xman]

Do you feel lucky? 

[Smartie117]

I had mine into 0 the other day for about 10 miles but I was sitting on the edge of my seat to here the unhealthy chug as they run out! 

[Chilli1]

23 hours ago, xman said:

Do you feel lucky? 

 

Nope!

[Chilli1]

18 hours ago, Smartie117 said:

I had mine into 0 the other day for about 10 miles but I was sitting on the edge of my seat to here the unhealthy chug as they run out! 

 

I've had it on zero for a few miles before but I've always wondered what the true limit is.

[Ootohere]

Would depend on your speed and how steep a hill you start climbing.

[GreenOcty1]

When it hits Zero, you know it's being cautious just not 'how' cautious.

Brim the tank, subtract the litre count you've just put in (+2 for pipe) from the tank capacity - (If you get a zero or negative figure call that a lucky escape)

Use the result to calculate miles left from your average mpg (4.546 litres = 1 imperial Gallon)

 

But it's not a nice job to purge a fuel system that's been clogged with tank bottom crud.

Much safer to use the warning light for it's intended purpose when there's still a gallon or so sloshing about.

[Breezy_Pete]

2 minutes ago, GreenOcty1 said:

But it's not a nice job to purge a fuel system that's been clogged with tank bottom crud

You know that the fuel pump sucks fuel from the bottom of the tank all the time irrespective of how much fuel there is in the tank, right?

[GreenOcty1]

1 minute ago, Wino said:

You know that the fuel pump sucks fuel from the bottom of the tank all the time irrespective of how much fuel there is in the tank, right?

Yes,

As the tank empties the actual flow rate across the very bottom increases and starts to move debris.

The feed pipe is sucking from a 3 dimensional volume, as the level lowers below the radius of the pipe, more fuel begins to enter from the sides not immediately ahead of the inlet (clear fluid).

Also the sloshing will wash any crud about. 

So basically its the last half litre leaving the tank that causes the problem, driving with a normal fuel level pulls the same crud in at a much lower rate and the filter takes care of it.

[Breezy_Pete]

5 minutes ago, GreenOcty1 said:

As the tank empties the actual flow rate across the very bottom increases and starts to move debris

 

You don't think that any such debris would be hurled about wholesale as you go round corners/brake/accelerate?

Just doesn't make any sense.

 

[Ootohere]

GreenOcty1,

Look in modern tanks that are not buckets of rust and see just what debris there is in the bottom. Or not as the case id often,

Thank goodness for filters, and those that change fuel filters, even if the Service Desk staff says they are Life long Filters.

 

Remember in UK winters the Winter Spec Fuel is arriving in the next few weeks, and keep fuel tanks full as much as possible and try reducing the condensation on the fuel tank walls.

Inside the tank that is.

Edited 3 October, 2018 by Offski

[GreenOcty1]

5 minutes ago, Wino said:

 

You don't think that any such debris would be hurled about wholesale as you go round corners/brake/accelerate?

Just doesn't make any sense.

 

It does get moved about, and is normally pulled through the system in a very small ratio to the fuel. It's just the sudden arrival of more than usual that causes problems.

One of the few benefits to hooligan driving is the crud not getting a chance to settle so running out is less likely to involve a blockage.

 

Offski has a point though, more of an old car issue, and these days with far fewer fuel stations about the amount of crud getting transferred into cars is much more evenly spread due the station tank contents being cycled so often the crud there doesn't have time to settle.

Donkeys years ago getting a fill up from a forecourt that was due its first delivery in weeks and never cleaned since dot could easily add more than your fair share of nasty stuff. you only needed one or two such visits a year to result in a blockage when running short. I'm just erring on the cautious side. my '80s scooby would clog its fuel filter in only 30k without running the thing low deliberately.