Fuel Supply Issues:
* Fuel Pump Failure: The most common culprit is a failing fuel pump. It might not be supplying enough pressure or might be completely inoperative.
* Fuel Pump Relay: The fuel pump relay might be faulty, preventing the pump from receiving power.
* Fuel Filter Clogging: A clogged fuel filter can restrict fuel flow.
* Fuel Lines: Fuel lines can become clogged, damaged, or leak, interrupting fuel flow.
* Fuel Tank Problems: Issues with the fuel tank, like a clogged vent or a faulty sending unit, can affect fuel delivery.
Carburetor Issues:
* Clogged Fuel Inlet: The carburetor's fuel inlet can become clogged, preventing fuel from entering.
* Float Level Problems: A problem with the float level can lead to an empty bowl, stopping fuel flow.
* Diaphragm Issues: The carburetor diaphragm can tear or become damaged, preventing fuel from being drawn from the bowl.
Other Possibilities:
* Electrical Issues: Problems with wiring or connections can disrupt the flow of electricity to the fuel pump or other related components.
* Vacuum Issues: A vacuum leak can disrupt the operation of the carburetor.
How to Troubleshoot:
1. Check for Fuel Pressure: Using a fuel pressure gauge, test for adequate fuel pressure at the fuel rail.
2. Inspect the Fuel Pump: Look for signs of damage, corrosion, or leaks. If possible, test the pump directly to ensure it's functioning.
3. Check the Fuel Filter: Replace the fuel filter if it's dirty or clogged.
4. Examine Fuel Lines: Look for leaks, damage, or blockages in the fuel lines.
5. Inspect the Carburetor: Check for clogs or damage to the fuel inlet, float, and diaphragm.
6. Check for Vacuum Leaks: Use a vacuum gauge to check for leaks in the vacuum system.
7. Diagnose Electrical Problems: Use a multimeter to test for voltage at the fuel pump and other components.
Important Notes:
* Working with fuel systems requires caution. Always disconnect the battery before working on electrical components.
* If you are not comfortable working on your vehicle, it's best to take it to a qualified mechanic.
* For specific troubleshooting steps, consult a repair manual for your 1987 Cadillac Seville.
Remember, a proper diagnosis requires a systematic approach and the use of appropriate tools. Good luck!
