Running on empty runs risk of trouble
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I did the honourable thing recently and nominated myself as the sober driver after a family celebration. Watching six adults argue over and work out seating arrangements and then getting themselves comfortable in a 7-seater petrol SUV was hilarious enough, but it was the first big test the Mitsubishi Outlander passed with flying colours.
Its second challenge was getting me to the nearest gas station before it ran out of petrol as the low level fuel warning light had illuminated almost immediately after our reasonably long journey had even started.
It’s amazing how alcohol loosens the tongues and how all of a sudden people become experts on a number of different subjects. In this case, the great debate within the cabin was just how far would the Outlander go with the warning light on before it ran out of fuel, and what were the dangers of running the tank so low on a regular basis.
Lots of discussion but no real answers later, I was left alone with $40 in my hand after a quick whip around from the passengers followed by waves of good luck, and I headed home feeling confident I was going to reach a refuelling station without too many problems.
The exact distance a vehicle will travel with the fuel warning light on is impossible to state as there are a number of different factors that need to be taken into account. Excessive weight and challenging terrain are obvious downsides and conditions that do not make for economical driving. On the positive side, drivers normally switch to economy mode automatically when they have that warning light staring them in the face, and will try to stretch the fuel consumption as far as possible.
As a general rule of thumb, drivers can count on getting between around 50 to 60 kilometres from the moment the warning light comes on until they reach a gas station. But like me I’m sure there are plenty of readers who have achieved a lot more. I remember carrying out a fuel consumption trial a couple of years ago where the vehicle had to run out of fuel completely to complete the test.
The Pukekohe race track was booked to complete the test run. The car circled the track happily for some time and travelled over 100 kilometres with the warning light on before stuttering to a stop.
But running the tank low on a regular basis is not a practice the industry or manufacturers would recommend. Fuel should be added well before the gauge hits that empty mark but I’m sure most of us have been caught short on occasions and driven with the warning light on for a limited distance with no issues.
Fuel tank design these days means some vehicles will run until almost the last drop of fuel has been used without any noticeable engine performance issues. However, some of the owners handbooks I have glanced over when researching this subject, suggest catalytic convertors (part of the emission system) can suffer damage if the fuel level gets to a point where engine misfiring is noticed. That I would suspect is for vehicles that have tanks where fuel can swirl around, and when levels are low,leaving the pump pickuppoint gasping for fuel that isn’t available.
When we talk in general terms on subjects like this, we need to take into account the different types of fuel pumps used and their location. For example, some of the older fleet have mechanical or electric pumps installed separate from the tank, while the trend in recent years has been to fit electric pumps inside the fuel tank itself and submerged with the fuel. In this situation the fuel helps keep the pump temperatures down to help protect the pump and extend its life. When fuel levels are consistently kept low however,there is a real chance of the pump overheating due to a lack of surrounding fuel.
The industry can tell stories of unusual and premature electric fuel pump failures where the pump has been located inside the tank. When owners have been questioned on their refuelling habits they often readily admit to continuously running their vehicles with very low fuel levels.
Restarting a petrol engine after it has run out of fuel is not normally a problem. It’s more the inconvenience it creates plus the risk of causing a major road hold up or even an accident especially in heavy traffic (on the Auckland Harbour Bridge for example) that drivers should fear most.
Diesel engines are another matter completely. Bleeding the fuel system is usually required before the engine will restart while,according to one owner’s manual I read, even cranking the engine over for long periods in an attempt to get the engine to fire should also be avoided.
The best practice is to keep the fuel levels above the quarter empty mark to help stay out of possible trouble. If you do get caught out and the warning light comes on, then get to a refuelling station as quickly as possible. Yes, you do have some breathing room to stop the immediate panic. Just don’t make it a regular habit, as it may come back to hurt you in more ways than one.
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