* Weak Spark: While you say you have a spark, "orange" suggests the spark isn't strong enough. This could be due to:
* Ignition Coil: A failing coil won't produce a strong enough spark to ignite the fuel consistently.
* Ignition Module (or Control Module): This component controls the ignition system. A faulty module can lead to weak or inconsistent sparking.
* Spark Plugs and Wires: Worn or damaged spark plugs or wires can hinder spark delivery. Even if they *look* okay, they might be the problem. Check for cracks or corrosion.
* Distributor Cap and Rotor (if applicable): Older vehicles might use a distributor. Check for wear, cracks, or carbon buildup.
* Crankshaft Position Sensor (CKP): This sensor tells the computer the engine's rotational position, crucial for proper timing of the spark. A faulty CKP will prevent starting.
* Cam Position Sensor (CMP): Similar to the CKP, a malfunctioning CMP will disrupt the ignition timing.
* Fuel Injectors: Even with good fuel pressure, injectors could be clogged or failing to deliver fuel properly. You might need to test their operation.
* Computer Issues (PCM/ECM): The Powertrain Control Module (PCM) or Engine Control Module (ECM) could be faulty and preventing proper ignition and fuel delivery, despite good pressure and a seemingly present spark. This is less likely but possible.
* Security System: Does the vehicle have a factory or aftermarket anti-theft system? It might be preventing starting.
Troubleshooting Steps:
1. Verify Spark Strength: Use an inline spark tester to quantitatively measure the spark's strength. A weak spark is often the culprit.
2. Inspect Spark Plugs and Wires: Replace them if they show any signs of wear or damage.
3. Check Ignition Coil: Test the coil's resistance using a multimeter, comparing it to specifications in your vehicle's repair manual.
4. Test CKP and CMP Sensors: Use a multimeter or a scan tool to test their output. These tests require some automotive knowledge.
5. Check Fuel Injectors: Listen for the click of the injectors when the engine is cranking. You can also use a noid light to confirm injector pulse.
6. Scan for Diagnostic Trouble Codes (DTCs): Use an OBD-II scanner to check for any stored trouble codes that might provide clues.
7. Check for Security System Issues: If the vehicle has an alarm system, see if it might be preventing the engine from starting.
If you're not comfortable with these checks, it's best to take the Suburban to a qualified mechanic. They have the tools and expertise to diagnose and fix the problem efficiently. Throwing parts at it randomly is inefficient and costly.
