1. Fuel Pump Issues:
* Problem: Older fuel pumps, especially those that are mechanically driven (common in '71 Mustangs), can be damaged by running dry. The pump might have seized or suffered internal damage from running without lubrication provided by the fuel itself.
* Troubleshooting: Listen carefully for the fuel pump's whirring sound when you turn the ignition key to the "on" position (but *before* cranking). If you don't hear it, the pump might be the culprit. You'll likely need a mechanic or a fuel pump replacement.
2. Fuel Filter Clogging:
* Problem: When the tank runs dry, debris that has settled at the bottom can be sucked into the fuel filter, clogging it.
* Troubleshooting: If the fuel pump is working, the next suspect is the fuel filter. Locate the fuel filter (consult your owner's manual), and check if fuel is flowing through it. Replacing the filter is relatively inexpensive and easy if you're mechanically inclined.
3. Carburetor Issues (if applicable):
* Problem: If your Mustang has a carburetor, running out of gas can lead to it becoming dry and needing to be primed. This can also cause the carburetor to become starved of fuel and require some time to re-prime.
* Troubleshooting: This often involves manually pumping the accelerator pedal a few times to prime the carburetor. If this does not work, it may need cleaning or servicing.
4. Electronic Fuel Injection (EFI) Issues (less likely for a '71 but possible with modifications):
* Problem: If you have an aftermarket EFI system, it might have sensors or components that are sensitive to fuel starvation.
* Troubleshooting: This will require more advanced diagnostic tools and expertise.
5. Ignition System:
* Problem: Although unrelated to running out of gas, sometimes the act of trying to crank a car repeatedly when it doesn't start can drain the battery, impacting the ignition system.
* Troubleshooting: Check the battery voltage. Jump-starting the car might be necessary.
What to do:
1. Refuel: Make absolutely sure you've added enough gas.
2. Listen for the Fuel Pump: Check for the whirring sound as described above.
3. Check the Fuel Filter: Inspect and/or replace if necessary.
4. Prime the Carburetor (if applicable): Pump the accelerator pedal a few times.
5. Jump Start: Consider jump-starting your car if the battery is weak.
If none of these steps work, you'll likely need to call a mechanic. A '71 Mustang might require specialized knowledge for troubleshooting, especially with fuel system problems. Don't continue cranking the engine repeatedly if it won't start – it could cause further damage.
