Fuel System:
* Low fuel: Check the fuel level. Seems obvious, but it's the easiest thing to check first.
* Fuel filter: A clogged fuel filter will restrict fuel flow. Replace it if necessary.
* Fuel pump: The lift pump (supplies fuel to the injection pump) might be failing. Listen for it to hum when the key is turned on. A weak or no hum suggests a problem. The high-pressure injection pump itself could also be failing.
* Water in fuel: Water in the fuel can cause numerous problems, from clogged filters to corrosion. Drain the fuel/water separator.
* Fuel lines: Check for leaks or blockages in the fuel lines.
* Fuel injectors: Faulty injectors can prevent proper fuel delivery. This usually requires professional diagnosis.
Electrical System:
* Battery: Test the battery voltage. A weak or dead battery is a common cause of no-start.
* Battery cables: Check for corrosion or loose connections on the battery terminals and cables.
* Starter: A faulty starter motor will prevent the engine from cranking. Have it tested.
* Alternator: While not directly a no-start issue, a bad alternator won't charge the battery, causing future starting problems.
* Wiring: Check for any damaged or corroded wiring, especially around the starter and fuel system components.
* PCM (Powertrain Control Module): A faulty PCM can prevent the engine from starting. This requires professional diagnosis with a scan tool.
* Ignition switch: A faulty ignition switch might not be sending power to the starter.
Engine:
* Glow plugs (for cold starts): If the engine is cold, failing glow plugs can prevent starting. Test them with a multimeter. This is more common in cold weather.
* Compression: Low compression in one or more cylinders will prevent starting. This requires a compression test.
* Timing: Although less likely, a timing issue (if the engine has a timing belt) could prevent starting.
* Crankshaft position sensor (CKP sensor): This sensor tells the PCM the position of the crankshaft; a faulty sensor can prevent starting.
Troubleshooting Steps:
1. Check the obvious: Fuel level, battery voltage, and obvious loose connections.
2. Listen for the fuel pump: Turn the key to the "on" position (don't crank) and listen for the fuel pump to hum.
3. Check the glow plug indicator light: If it doesn't come on (or stays on too long), there could be a glow plug or relay issue.
4. Attempt to crank the engine: Does it crank slowly, quickly, or not at all? This will help narrow down the possibilities.
5. Use a code reader/scan tool: A scan tool can read diagnostic trouble codes (DTCs) stored in the PCM, providing valuable clues.
Important Note: Diagnosing a no-start condition can be complex. If you're not comfortable working on your vehicle's electrical and fuel systems, it's best to take it to a qualified mechanic, especially one familiar with Cummins diesel engines. Improperly diagnosing and repairing a diesel can lead to costly damage.
