Here's a breakdown of potential problems and how to check them:
1. Check the Fuel Pump Relay:
* Location: Consult your car's repair manual for the exact location of the fuel pump relay. It's often in a fuse box under the hood or inside the car's cabin.
* Testing: Swap the fuel pump relay with a known good relay of the same amperage (a relay for something else like the horn or wipers, if they're similar). If the car starts after the swap, the original relay is faulty.
2. Check the Fuel Pump Fuse:
* Location: Similar to the relay, find the fuel pump fuse in a fuse box. Your owner's manual will tell you its location and amperage.
* Testing: Visually inspect the fuse for a blown element (a broken wire inside). Replace if necessary with a fuse of the correct amperage.
3. Check the Fuel Pump's Power Supply:
* Access the Fuel Pump: This usually requires dropping the fuel tank (a more involved process, best left to experienced mechanics unless you're comfortable working under the car and with fuel). You might be able to access it through an access panel under the car as well, dependent upon the model.
* Testing: With the key turned to "ON" (but not cranking the engine), use a multimeter to check for power at the fuel pump's wiring connector. You should have battery voltage (12V). If not, trace the wiring back towards the fuse box and relay to find the break in the circuit.
4. Check the Fuel Pump Inertia Switch (sometimes called a Crash Sensor):
* Location: This is a safety device that cuts power to the fuel pump in a collision to prevent fires. It's often located under the dash or in the engine compartment.
* Testing: Usually has a small button that needs to be pressed to reset it. Try pressing it.
5. Check the Fuel Filter:
* Location: Located somewhere in the fuel line. Your repair manual will show you where it's located.
* Testing: A clogged fuel filter restricts fuel flow. Replace it if it looks dirty or damaged.
6. Check the Fuel Pressure:
* Testing: This requires a fuel pressure gauge. You'll need to connect it to the fuel system's test port (location varies by model year). The pressure should be within the specifications listed in your repair manual. Low pressure indicates a problem with the fuel pump, filter, or fuel pressure regulator.
7. Check the Fuel Pump Itself:
* Testing (Advanced): If all else fails, the fuel pump itself could be faulty. As mentioned earlier, this involves dropping the fuel tank, which is complex and risky if not done correctly. This is usually best handled by a professional.
Important Considerations:
* Repair Manual: A repair manual specific to your 1990 Pontiac Le Mans is invaluable. It will provide diagrams, specifications, and step-by-step instructions.
* Professional Help: If you're not comfortable working on your car's fuel system, take it to a qualified mechanic. Working with fuel is dangerous and improper handling could lead to injury or fire.
By systematically checking these items, you should be able to pinpoint the cause of the fuel delivery problem. Remember to always prioritize safety when working on your vehicle's fuel system.
