1. Check the Fuel Pump:
* Listen for the pump: Turn the key to the "on" position (without starting the engine). You should hear a brief humming sound from the fuel pump (usually located in the fuel tank). If you don't hear it, the pump might be faulty or the fuel pump relay is bad.
* Check the fuel pump relay: Locate the fuel pump relay (consult your owner's manual or a wiring diagram). You can try swapping it with another relay of the same amperage (make sure to note which relay you remove and replace it in the same spot). If the problem goes away, the relay is likely the culprit.
* Check fuel pressure: This requires a fuel pressure gauge. Connect it to the fuel rail (you'll need an adapter). The pressure should be within the specifications listed in your owner's manual (typically around 30-40 psi, but this varies by engine). Low or no pressure indicates a pump, filter, or regulator problem.
2. Inspect the Fuel Filter:
* A clogged fuel filter restricts fuel flow. Locate the filter (often near the fuel pump or along the fuel line) and replace it. This is a relatively inexpensive and easy fix that often resolves fuel delivery issues.
3. Examine the Fuel Injectors:
* Check for power and ground: With the engine off, use a multimeter to check if the injectors are receiving power and ground. A wiring diagram is essential here. You'll need to access the injector connectors. Lack of power or ground indicates a wiring issue.
* Injector pulse test: This requires an oscilloscope or a specialized scan tool capable of monitoring injector pulse width. A faulty injector will either not pulse or pulse incorrectly. This step usually requires more specialized equipment.
4. Investigate the Fuel Pressure Regulator:
* The fuel pressure regulator maintains the correct fuel pressure in the fuel rail. A faulty regulator can cause low fuel pressure or a leak, preventing fuel from reaching the throttle body. It's often located on the fuel rail.
5. Check Fuel Lines and Connections:
* Inspect the fuel lines for cracks, leaks, or kinks. Check all connections for proper seating and tightness. A leak anywhere in the line will prevent fuel from reaching the injectors.
6. Consider the Throttle Position Sensor (TPS):
* Although less likely to be the direct cause of no fuel at the throttle body, a faulty TPS can sometimes prevent the fuel injectors from receiving the signal to open. A scan tool can check the TPS voltage.
7. ECM/PCM Issues:
* In rare cases, a problem with the Engine Control Module (ECM) or Powertrain Control Module (PCM) – the computer – can prevent the fuel injectors from being activated. This is usually diagnosed with a scan tool that can read diagnostic trouble codes (DTCs).
Important Considerations:
* Safety: Work in a well-ventilated area. Gasoline is flammable and its vapors are dangerous.
* Professional Help: If you are not comfortable performing these checks, it's best to take your vehicle to a qualified mechanic. Improperly working on your fuel system can be hazardous.
* Year and Engine: The specifics of your fuel system depend on the exact year and engine of your Cutlass Calais. Consulting a repair manual specific to your vehicle is highly recommended.
By systematically checking these components, you should be able to pinpoint the source of the problem and get your 1991 Oldsmobile Cutlass Calais running again. Remember to always prioritize safety when working on your vehicle.
