Beware-Very Good Distance to Empty - New Wolfy TLDR: 62.9 fillup on 60 litre tank

[Sydneykid]

As the return fuel cools down in the fuel tank the condensation will form.
Running always almost on empty is not good and the above is only one of the reasons, Gary.

How does the water vapour (to be condensed) get into the fuel that is returned from the engine? It's a sealed system, for example the fuel pressure regulator is isolated from the atmosphere by the diaphragm. It's pretty simple, if there were any openings for water vapour to get in then the fuel would get out. In general returned fuel from the engine bay is warmer than the ambient temperature, logical since it's been in the hot engine bay. We measure fuel temp in the long distance race cars so I'm pretty familiar with fuel temp climb as the tank empties. The return of the fuel actually increases the temperature of the fuel in the tank, and as the tank empties (ie; there is less fuel in the tank in comparison to what is being returned) the temperature increase is greater. As an aside that's why we run fuel temp compensation as well as air temp in the race cars, and in the Porsches we run fuel coolers. As a result running less fuel in the tank would result in less condensation, if there was any water vapour there to condense.

Obviously the fuel tank needs to take in air to replace the fuel as it is used but that is filtered by the carbon (charcoal) canister to eliminate any water vapour getting sucked into the tank.

I wasn't suggesting "running always almost on empty", what I was suggesting was that running the tank to almost empty regularly was a good thing. Sediment doesn't build up and water (mostly from the servo) doesn't accumulate at the bottom of tank.

Back in the days of sintered bronze filters even a tiny drop of water was bad news, but these days a minuscule amount of water in the fuel is not an issue as the high pressure in the fuel filter mixes it as it passes though. Obviously a large amount of water is always an issue.


Cheers
Gary

[Sydneykid]

Plus the fuel pump isnt sentient. It doesn’t know to exclude water when sucking in liquid.
I’d rather an engine running on a supply of 15+l fuel to 100ml water, than 3l fuel and still having 100ml water. Think about a horrible cordial/alcohol that you need to drink out of politeness/a dare. You dilute the hell out of it with water/coke!
Just coz it’s heavier doesn’t mean it doesn’t get splashed about and ‘mixed’ with the fuel. Same story with old tanks and crud build up.
I personally don’t care that much about it, but to say it is a non-issue isn’t correct.

Exactly, that's why you want to use up the water before it accumulates, using your example don't let it accumulate to 100 mls over 10 tanks, suck it up at 10ml per tank. Because one day you are going to have to use all the fuel in the tank and you'll get the big dose all at once.

Cheers
Gary

[mrfresh]

Managed just under 850Kms full to zero, same Allspace 162 with just me (no passengers or luggage), Eco mode for most of it along the Hume (Mel to SYD outer fringes), I figure that's about as good as it gets.