Here's a breakdown of how to troubleshoot this, starting with the most likely culprit:
1. Fuel Pump and Delivery System:
* Listen for the pump: When you turn the key to the "on" position (but not cranking), you should hear the fuel pump prime for a few seconds. If you don't hear it, the pump itself, its relay, or its fuse/circuit breaker could be the problem.
* Check the fuel pressure: This requires a fuel pressure gauge. You need to know the correct fuel pressure specification for your 1984 Cutlass's engine. Low pressure or no pressure after a few hours suggests a pump, pressure regulator, or even a leak in the system. Pressure should be maintained even after the engine cools.
* Inspect the fuel filter: A clogged fuel filter can restrict fuel flow, especially when the fuel has had time to settle. A new filter is cheap and easy to replace.
* Check the fuel lines: Look for any cracks, leaks, or loose connections in the fuel lines.
* Fuel pump relay: Locate the fuel pump relay (consult your owner's manual or an online repair manual). Try swapping it with a known good relay of the same amperage rating (you can find this on the relay itself). A failing relay can exhibit intermittent problems.
2. Computer/Electrical System (Less Likely, but Possible):
* Check the crankshaft position sensor (CKP sensor): A faulty CKP sensor prevents the computer from knowing the engine's position, preventing ignition. This can sometimes be temperature-related, but it would likely cause problems immediately after the engine shuts down, rather than just after a few hours.
* Check other sensors: Other sensors like the coolant temperature sensor (CTS) can affect the fuel delivery strategy. A faulty CTS could give the computer incorrect information, leading to a lean mixture and preventing starting.
* Battery and charging system: A weak battery can cause starting problems, especially after the engine has been off for a while. Test the battery's voltage and make sure the alternator is charging properly.
Troubleshooting Steps:
1. Start with the fuel pump: It's the simplest and most likely culprit. Listen for it priming and then check the fuel pressure if possible.
2. Check the fuel filter: This is an easy, inexpensive step that could solve the problem.
3. Inspect fuel lines visually: Look for leaks or damage.
4. If the fuel system checks out okay, then start investigating the sensors mentioned above (CKP, CTS). This will require more automotive knowledge and testing equipment.
5. Consider a professional diagnosis: If you're not comfortable troubleshooting electrical systems or fuel delivery, take it to a qualified mechanic. They have the tools and experience to diagnose the problem accurately.
Remember safety first. Work in a well-ventilated area, and be aware of fuel system pressure. Always disconnect the negative battery terminal before working on any electrical components. A Haynes or Chilton repair manual specific to your 1984 Oldsmobile Cutlass will be extremely helpful in locating components and understanding the fuel system.
