How to troubleshoot fuel delivery issues on a 1968 Ford Mustang GT Fastback (Bullitt)?

Experiencing fuel delivery issues in your 1968 Ford Mustang GT Fastback (Bullitt) can be a common problem that manifests as difficulty starting the engine, poor acceleration, or even engine stalling. These symptoms can be frustrating, but understanding how to properly diagnose and address the issue can get your classic muscle car back on the road. Here is how to solve this issue:

Step 1: Inspect the Fuel Tank and Lines

Start by inspecting the fuel tank and lines for any visible signs of damage or leaks. The fuel tank is located at the rear of the car. Check for rust or corrosion, particularly around the seams where the tank connects to the fuel lines. Look for any wet spots or the smell of gasoline, which would indicate a leak.

Step 2: Check the Fuel Pump

Locate the fuel pump, which is typically mounted on the engine block on the passenger side. The fuel pump on a 1968 Mustang is a mechanical type with a round, slightly domed appearance. Inspect for any leaks around the gasket or fittings. To test the fuel pump's operation, disconnect the fuel line from the carburetor and place it into a small container. Crank the engine and observe if fuel is being pumped out. If not, the fuel pump might be faulty and need replacing.

Step 3: Examine the Fuel Filter

Find the fuel filter, usually located along the fuel line between the tank and the carburetor. On the Mustang, it's typically a small metal or plastic canister. Remove the fuel filter and check if it’s clogged. You can do this by blowing through the inlet side; if air does not flow freely, the filter is blocked and should be replaced.

Step 4: Inspect the Carburetor

The carburetor, located on top of the engine, is the part that mixes fuel with air before it enters the combustion chamber. If the fuel pump and filter are working correctly, the issue might lie within the carburetor. Remove the air cleaner to access the carburetor, which looks like a metal block with a series of rods and levers. Check for fuel in the carburetor bowl by removing the top cover. If the bowl is empty or fuel levels are low, there might be an obstruction in the fuel line or needle valve within the carburetor.

Step 5: Verify Fuel Pressure

Using a fuel pressure gauge, test the fuel pressure at the carburetor inlet. Attach the gauge to the fuel line and crank the engine. For a 1968 Mustang, the fuel pressure should typically read between 4 to 7 PSI. If the pressure is too low, it could indicate a weak fuel pump or clogged fuel lines.

Step 6: Inspect the Fuel Sending Unit

The fuel sending unit, located inside the fuel tank, is responsible for measuring the amount of fuel and sending that information to the fuel gauge. To check it, you’ll need to access the top of the fuel tank where the unit is mounted. Disconnect the electrical connections and the fuel line, then remove the sending unit. Inspect for any visible damage or corrosion on the float and connections.

Step 7: Test Electrical Connections

For the electric components involved in fuel delivery, such as the sending unit and any electric fuel pumps (if your Mustang has been retrofitted), verify that all wiring is intact and connections are clean and secure. Look for frayed wires or corroded connectors that could interrupt the electrical supply.

By following these steps, you should be able to diagnose and solve most fuel delivery issues in your 1968 Ford Mustang GT Fastback (Bullitt). Restoring the proper fuel flow not only ensures your car runs smoothly but also preserves the integrity and performance of this classic vehicle.