Running On Fumes
We've all done it. The low-fuel warning light comes on, but instead of stopping at the nearest gas station, we decide there's probably enough left to get home. After all, what's the harm in squeezing a few more miles out of the tank? As it turns out, regularly driving on fumes can cause problems that go well beyond the inconvenience of running out of gas.
Your Fuel Pump Needs Gas
Most modern gasoline-powered cars use an electric fuel pump located inside the fuel tank. Gasoline flowing through the pump helps cool and lubricate its internal components. When fuel levels become extremely low, particularly during sharp turns or hard acceleration, the pump may temporarily draw air instead of gasoline. Repeated fuel starvation can contribute to premature pump wear.
Does Gasoline Keep It Cool?
You've probably heard that keeping your tank full prevents the fuel pump from overheating. There's some truth to that, but the explanation is often exaggerated. Many in-tank pumps rely primarily on fuel passing through them for cooling, rather than simply being submerged in gasoline. A low tank isn't automatically damaging, but repeatedly running the pump dry certainly isn't good for it.
What About Tank Sediment?
Another popular warning claims that driving with an almost empty tank causes your engine to suck up dirt and sediment that has accumulated at the bottom. However, fuel pumps generally draw gasoline from near the bottom of the tank anyway. Modern vehicles also have fuel-pump strainers and filtration systems. Contaminated fuel can cause problems, but low fuel levels don't suddenly make settled debris enter the engine.
Your Engine Could Stall
The most immediate danger is running out of gasoline while driving. As fuel pressure drops, your engine may hesitate, misfire, lose power, or shut off completely. Although steering and braking generally remain possible, power assistance may be reduced or lost. That can be especially dangerous on highways, during turns, or in heavy traffic where an unexpected loss of power leaves little room to react.
Can It Damage Other Components?
Fuel starvation can also affect engine operation. When gasoline delivery becomes inconsistent, the engine may run poorly or misfire. Repeated misfires can potentially damage the catalytic converter, especially if unburned fuel reaches the exhaust. However, occasionally driving with the warning light illuminated doesn't mean you're automatically damaging the converter or other expensive components.
How Much Gas Is Left?
The low-fuel warning light doesn't mean your tank is completely empty. Many vehicles have enough gasoline remaining for approximately 30 to 50 miles of driving, although the actual distance varies considerably. Your vehicle's fuel economy, tank capacity, and manufacturer settings all matter. Check your owner's manual rather than assuming every vehicle has the same reserve.
Don’t Trust The Range Display
Modern cars often display an estimated number of miles until empty. Unfortunately, that number isn't a guarantee. AAA testing found that distance-to-empty estimates can vary significantly depending on driving conditions. Stop-and-go traffic, hills, cold weather, and aggressive acceleration can all reduce your remaining range. A display showing 20 miles doesn't necessarily mean you'll make it another 20 miles.
Is A Quarter Tank Enough?
AAA recommends refueling when your gauge reaches approximately one-quarter of a tank. That's a sensible guideline rather than a precise mechanical threshold. It provides a buffer against unexpected traffic delays, detours, or closed gas stations while reducing the likelihood of running the fuel pump dry. You don't need to keep the tank completely full to protect your car.
What If You Run Out?
If your engine begins losing power, activate your hazard lights and steer toward a safe stopping place. Don't repeatedly crank the engine after it runs out of gasoline. Once you've added fuel, follow your owner's manual's restarting instructions. Some vehicles may require several attempts to restore fuel pressure, while diesel engines can require a more involved priming procedure.
The Bottom Line
Occasionally letting your fuel gauge approach empty probably won't destroy your car. The bigger concern is making it a regular habit, particularly if you repeatedly run the tank so low that the fuel pump draws air. Keeping at least a quarter tank provides inexpensive insurance against mechanical problems and roadside emergencies. The few minutes saved by skipping a gas station simply aren't worth the gamble.
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