* Ignition System: This is the most likely culprit if fuel pressure is good. Check these components:
* Distributor Cap and Rotor: Look for cracks, corrosion, or worn contacts. A simple visual inspection is often sufficient.
* Ignition Coil: Test the coil's primary and secondary windings using a multimeter or a dedicated coil tester. A weak coil won't provide sufficient spark.
* Spark Plugs and Wires: Inspect the plugs for fouling, cracks, or excessive wear. Check the wires for cracks, damage, or loose connections. A weak spark in one or more cylinders can prevent starting. Replace them if they're questionable.
* Crankshaft Position Sensor (CKP): This sensor tells the ECM when the engine is turning. A faulty CKP will prevent the ECM from sending a spark signal. A scan tool might reveal a CKP code.
* Camshaft Position Sensor (CMP): Similar to the CKP, a bad CMP sensor prevents proper ignition timing.
* Ignition Control Module (ICM): This component can fail and prevent spark delivery. This is less common but possible.
* ECM (Engine Control Module): A faulty ECM can prevent the engine from starting even with fuel and spark, as it's the brain of the operation. This is a less likely but possible cause. A scan tool may be needed to diagnose ECM issues.
* Security System (if equipped): If the truck has a factory or aftermarket anti-theft system, a malfunctioning system could be preventing the engine from starting.
* Air Intake System: Check for blockages or restrictions in the air intake system (air filter, MAF sensor). While less common, a severe restriction can prevent starting.
* Low Compression: While less likely if it's cranking strongly, low compression in one or more cylinders could prevent starting. A compression test is needed to diagnose this.
Troubleshooting Steps:
1. Visual Inspection: Thoroughly inspect all ignition components for obvious damage.
2. Spark Test: The easiest way is to remove a spark plug, ground it to the engine block, and crank the engine while looking for a strong, blue spark. Repeat for other cylinders. If spark is weak or absent, focus on the ignition system components.
3. Scan Tool: Use a scan tool (OBD1 reader for a 1994 vehicle) to check for diagnostic trouble codes (DTCs). This will often point to the faulty component.
4. Compression Test: If spark is good, a compression test will help determine if there are any internal engine issues.
Start with the easiest and most common causes (spark plugs, wires, distributor cap and rotor) before moving to more complex components (sensors, ECM). If you're not comfortable working on the ignition system yourself, it's best to take it to a qualified mechanic.
