Here's a breakdown of more likely causes, starting with the most common:
* Weak Battery: Even if the battery seems okay, it might not have enough juice to consistently crank the engine. Have the battery and charging system tested at an auto parts store. This is the cheapest and easiest thing to check first.
* Faulty Starter: A failing starter motor can sometimes crank weakly or intermittently. This is a common reason for the "almost starts" symptom.
* Bad Connections: Corroded or loose battery cables, starter cable connections, or even ground straps can impede the flow of electricity and prevent the engine from cranking properly. Check all these connections for cleanliness and tightness.
* Fuel Pump (Your Question): A failing fuel pump might not deliver enough fuel pressure to start the engine, resulting in weak cranking or no start. This is less likely if the engine *almost* starts. If the pump was completely dead, you'd likely hear nothing beyond the normal cranking sounds. However, a pump that's weak or intermittently failing could produce this symptom. A fuel pressure test is needed to confirm.
* Crank Position Sensor (CPS): This sensor tells the computer the position of the crankshaft. A faulty CPS will prevent the engine from starting.
* Cam Position Sensor (CMP): Similar to the CPS, a faulty CMP prevents the engine from starting.
* Ignition System Issues: Problems with the ignition coil, ignition module, or spark plugs can prevent the engine from firing even if it cranks.
How to Proceed:
1. Battery and Charging System Test: This is the most crucial first step. Get it tested professionally.
2. Check Battery Cables and Connections: Look for corrosion and loose connections. Clean and tighten them if necessary.
3. Listen Carefully During Cranking: Does the engine sound weak, or is there a clicking sound? This can help pinpoint the problem.
4. Fuel Pressure Test: If the battery and connections are good, a fuel pressure test can determine if the fuel pump is delivering sufficient pressure. This usually requires a fuel pressure gauge.
5. Professional Diagnosis: If you can't identify the problem yourself after these steps, take the car to a qualified mechanic for proper diagnosis. They have the tools and expertise to identify the issue quickly and efficiently. Trying to troubleshoot advanced ignition system issues without the proper tools can be time-consuming and frustrating.
In short, while a weak fuel pump *could* be the cause, it's not the most likely culprit given the "almost turns over" description. Start with the simpler, cheaper checks (battery and connections) before moving on to more complex diagnostics.
