How to troubleshoot fuel delivery issues on a 1970 Plymouth Hemi 'Cuda?

Troubleshooting fuel delivery issues on a 1970 Plymouth Hemi 'Cuda can be a meticulous but rewarding task. If your 'Cuda is experiencing difficulties such as sputtering, stalling, or failing to start, these could all indicate problems with the fuel delivery system. Here is how to solve this issue.

Step 1: Verify Fuel Level

First and foremost, ensure that your 1970 Plymouth Hemi 'Cuda has enough fuel in the tank. Open the fuel filler cap, which is located on the driver’s side rear quarter panel. It's a round metal cap and may require a key to unlock. Check the fuel gauge on the dashboard as well to confirm.

Step 2: Inspect the Fuel Pump

Locate the mechanical fuel pump, which is typically mounted on the engine block towards the front of the vehicle. It is a small, cylindrical metal device with fuel lines running to it. Examine it for any signs of leakage or damage. To test its function, you can use a fuel pressure gauge. Disconnect the fuel line from the carburetor and connect the gauge to the line. Crank the engine and check the pressure reading; it should be within the manufacturer's specifications.

Step 3: Check Fuel Lines and Filters

Inspect the fuel lines running from the fuel tank to the carburetor for any signs of cracks, leaks, or blockages. The lines are usually metal or rubber and run along the frame of the vehicle. The fuel filter, often found along the fuel line near the tank or the pump, is a small, cylindrical canister that can get clogged. Replace the filter if it appears dirty or clogged.

Step 4: Examine the Carburetor

The carburetor is located on top of the engine, mounted to the intake manifold, and it has several linkage rods and fuel lines connected to it. Remove the air filter housing to get a clear view. Check inside the carburetor for any dirt, debris, or signs of fuel starvation. You can also perform a basic functionality check by having an assistant pump the gas pedal while you look down into the carburetor; you should see fuel squirting into the throat of the carburetor, indicating the pump is working.

Step 5: Evaluate the Fuel Tank and Sending Unit

If the problem persists, you may need to check the condition of the fuel tank and the sending unit inside it. The fuel tank is located at the rear of the vehicle. You may need to drain and drop the tank to inspect it thoroughly. Look for signs of rust, sediment, or other contaminants that could be obstructing fuel delivery. The sending unit, which includes a float and a fuel pickup tube, should be checked for proper operation and cleanliness.

Step 6: Check for Vapor Lock

Vapor lock can occur when fuel vaporizes in the fuel line due to high temperatures, preventing liquid fuel from reaching the carburetor. Ensure that fuel lines are routed away from hot engine parts and properly insulated if necessary. Installing a heat shield or rerouting the lines can sometimes solve this issue.

By following these steps, you should be able to systematically diagnose and resolve fuel delivery issues on your 1970 Plymouth Hemi 'Cuda, ensuring it runs smoothly and reliably.