* Evaporative Emission (EVAP) System (if equipped): While less likely on a 1961 car, a partially blocked or malfunctioning EVAP system could prevent proper venting of the fuel tank. This is less probable since EVAP systems weren't as common then, but it's still possible something is clogging the vent lines.
* Clogged Fuel Tank Vent Line: This is the most common culprit. The vent line allows air to escape the tank as fuel enters, equalizing pressure. If it's clogged with debris, rust, or condensation, pressure builds, causing gas to overflow. This line typically runs from the tank to outside the car, often near the filler neck.
* Blocked Filler Neck: Check if the filler neck itself is obstructed. Something may be blocking the passage of air.
* Fuel Tank Pressure: A severely rusted or damaged fuel tank might create internal restrictions and impede proper venting. This is more likely given the age of the vehicle.
What you should do:
1. Safety First: Do *not* continue to slowly trickle fuel. This is a fire hazard. Stop filling the tank immediately.
2. Inspect the Filler Neck: Carefully examine the filler neck for any visible obstructions. A flashlight and possibly a small mirror might help.
3. Locate the Fuel Tank Vent Line: Try to locate the vent line. This usually involves some searching and potentially looking under the car. A repair manual or online forum specific to your 1961 Ford Falcon will be helpful here.
4. Clear the Vent Line (If Found): If you locate the vent line, attempt to clear it. You may be able to gently blow air through it (from the tank end, if safe to do so), or try a thin, flexible wire or pipe cleaner. *Be extremely careful not to damage the line*.
5. Check the Fuel Tank: If you suspect the tank is heavily rusted or damaged internally, you may need to replace it. This is a significant job.
6. Professional Help: If you cannot locate the vent line or clear it yourself, take the car to a mechanic specializing in classic cars. They have the experience and tools to diagnose and fix this problem safely.
Important Considerations:
* Fire Hazard: Working on a fuel system presents a significant fire risk. Always work in a well-ventilated area, away from open flames and sparks. Consider using non-sparking tools.
* Repair Manual: Obtain a repair manual specific to your 1961 Ford Falcon. This will provide diagrams and instructions to help you locate and repair the vent line.
Ignoring this problem is dangerous. Continuing to fill the tank in this way significantly increases the risk of a fuel spill and fire. Address this immediately.
