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Why you shouldn't let your fuel tank run too low

Did you just drive past that servo, and then nervously stare at your fuel gauge? It happens to the best of us and then the internal dialogue begins: “She’ll be right, I’ll make to the end of the highway before needing more”. And then, moments later: “Oh, man. It’s going down so quickly. This fuel gauge is a goddamn liar”. But the important fact is: I shouldn’t do this. And neither should you. Here is why you shouldn’t run your fuel tank down.


Fuel cools and lubricates the pump

This is the main reason, beyond any other. Running a fuel pump without fuel is like running an engine without coolant and oil. It’s a systematically bad idea. If you want your pump to live a long, ensure it’s always well submerged in fuel: The fuel actually cools the electric pump as it passes through, like coolant in your engine. It also lubricates the pump, reducing wear and tear significantly.


You might pick up some extra crud

When you’re fuel level runs low, your fuel is going to be sloshing around a bit more and splashing as you go around corners. What you’re doing is aggravating any crud or particles sitting in your tank, which will no-doubt be there on any vehicle with a few kays on the clock.


Air in your fuel system is bad

This goes without saying, obviously. Fuel tank and pump designs are made to keep the pump sucking down only the finest in fuels, without any air getting in there. But in the real world, it doesn’t always work out that way. Keep the air, by keeping a decent amount of fuel in the tank.

Only very old vehicles will have an inline pump or lift pump somewhere other than in the tank, just about every 4WD in recent memory will have an in-tank pump. The problem is that the pump might be really hard to access. Do you have to drop the tank completely to access the pump, or is there an access hole somewhere in the car? If you’ve got accessories like drawers or a fridge in the back, it’s worth checking if these get in the way.


Measuring your mileage

Want to figure out how much you’re getting from a tank? Don’t try and get every last metre before fuelling up; There’s a better way of going about it. What I do is fill up my car, either to the first click, or when I can physically see the fuel in the filler. This way, I know exactly how full the tank is. Reset your odometer, and drive off. Then, when your 4WD is somewhere between 1/2 and a 1/4 full, do the same thing.

But, instead of saying ‘I get XXX kms to my tank’, see how many litres it took to refill the tank to the same level. Then, you can accurately calculate your litres per hundred kilometres, or kilometres per litre, or furlongs per flagon, or whatever.


This article was originally published on Mr.4x4.

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