* Fuel pressure: Even with a new pump, there could be a problem with the fuel delivery system. You need to measure the fuel pressure at the fuel rail to confirm that sufficient pressure is reaching the injectors. A fuel pressure gauge is necessary for this. The pressure should be within the specifications listed in your Buick Regal's repair manual.
* Fuel injectors: The injectors might be clogged or faulty, preventing fuel from spraying into the cylinders. This can be checked by a mechanic with specialized tools or by replacing them if you suspect this is the problem.
* Cranking speed: Is the engine cranking slowly? A weak battery, faulty starter, or other starting system problems can prevent the engine from turning over fast enough to ignite the fuel. Test the battery voltage and check the starter motor.
* Ignition system: The ignition system needs to provide a spark to ignite the air/fuel mixture. Check the following:
* Spark plugs: Inspect them for wear, fouling, or damage. Replace them if necessary.
* Spark plug wires: Check for cracks, damage, or loose connections.
* Ignition coil: A faulty coil won't provide sufficient spark.
* Distributor (if applicable): Older models might have a distributor; check its cap, rotor, and internal components. The 1992 Regal might have a distributorless ignition system, but checking the ignition control module is still important.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's position and is critical for ignition timing. A faulty CKP will prevent the engine from starting.
* Air intake system: Check for any obstructions in the air intake system, such as a clogged air filter.
* Computer/ECM: In rare cases, a faulty Engine Control Module (ECM) can cause starting problems. This is more difficult to diagnose and usually requires professional help.
* Security system: If your car has a factory or aftermarket anti-theft system, it could be preventing the engine from starting.
Recommendation: Since you've already replaced the fuel pump, measuring fuel pressure is the next logical step. If that's good, then you'll need to start checking the ignition system components. If you're not comfortable working on the car's electrical system, it's best to take it to a qualified mechanic for diagnosis and repair.
