* Timing: Even with spark, the timing might be off. The distributor could be slightly out of alignment, or there could be an issue with the crankshaft position sensor (CKP sensor) or camshaft position sensor (CMP sensor). These sensors tell the computer when to fire the spark plugs. An improperly functioning sensor would cause mistiming even if you *see* spark.
* Compression: Low compression in one or more cylinders prevents proper combustion, even with fuel and spark. A compression test is crucial here. Worn piston rings, a blown head gasket, or valve issues can cause low compression.
* Cranking speed: Is the engine cranking over *strongly*? A weak battery, bad starter motor, or corroded battery connections can prevent the engine from turning over fast enough to ignite the air/fuel mixture.
* Ignition Coil: While you say you have spark, a weak or failing ignition coil might provide insufficient spark energy for reliable ignition, especially under load or in hot conditions. A spark tester that checks voltage *and* spark energy would be useful here.
* Fuel Pressure: While you say it's getting fuel, the *pressure* might be insufficient. A fuel pressure gauge is necessary to check this accurately. A weak fuel pump, clogged fuel filter, or regulator problems can all cause low fuel pressure.
Troubleshooting Steps:
1. Battery and Connections: Start by ensuring your battery is fully charged and the terminals are clean and tight. A corroded connection can dramatically reduce cranking power.
2. Compression Test: This is critical. Low compression points to a serious mechanical issue.
3. Fuel Pressure Test: A fuel pressure gauge connected to the fuel rail is needed to check fuel delivery pressure.
4. Timing Check: This is more advanced and may require a timing light and knowledge of your specific engine's timing specifications.
5. Ignition Coil Test: Use a spark tester to check the strength and energy of the spark. A weak spark may appear present but not be strong enough to ignite the fuel/air mix.
6. Check for Codes: Scan the vehicle's OBDII system for any trouble codes. This could give you valuable clues.
Don't overlook:
* Distributor cap and rotor: Cracked or worn components here can affect spark delivery.
* Spark plugs and wires: Worn spark plugs or bad wires can also disrupt ignition. It's relatively cheap to replace these.
If you're not comfortable performing these checks, taking the vehicle to a qualified mechanic is the best course of action. The problem could be something simple or more complex, and a proper diagnosis is essential before spending money on parts that might not solve the problem.
