After running your 2020 Subaru Forester completely out of fuel, simply adding gasoline may not be enough to restart the engine immediately. Air in the fuel system and fuel pump considerations require specific recovery steps.
Why Running Out of Fuel Causes Problems
When the fuel tank runs dry, air enters the fuel lines and fuel pump. Modern fuel pumps are cooled and lubricated by the fuel they sit in - running dry can cause pump damage or overheating. Additionally, air in the fuel lines must be purged before the engine receives proper fuel delivery.
Minimum Fuel Amount
Add at least 2-3 gallons of fuel to ensure the pump pickup is submerged. Smaller amounts may leave the pump uncovered and unable to draw fuel properly. Don't assume a gallon from a gas can will be sufficient.
Fuel System Priming
After adding fuel, turn the key to ON (not start) for about 5 seconds, then OFF. Repeat this cycle 5-6 times. Each cycle allows the fuel pump to run briefly, building pressure and pushing air out of the lines. This priming process is essential after fuel starvation.
Extended Cranking Attempts
After priming, the first start attempt may require extended cranking as the final air works through the system. Crank for about 10 seconds, rest for 30 seconds (to cool the starter), then crank again. The engine may sputter before finally catching as fuel reaches the injectors.
Fuel Pump Damage Assessment
If the Forester still won't start after proper priming and multiple fuel additions, the fuel pump may have been damaged from running dry. A pump that was failing before the fuel runout may have been finished off by the stress. Fuel pressure testing reveals pump health.
Preventing Future Runouts
Avoid running on empty regularly - fuel helps cool the pump, and sediment at the tank bottom can be drawn into the system when fuel level is critically low. Modern fuel gauges have buffer zones, so when the warning light comes on, you usually have more fuel than you think.