1. Check the fuel lines: Ensure that the fuel lines are not kinked or obstructed, and that they are properly connected to the fuel tank and the engine. Make sure that the fuel filter is clean and free of obstructions.
2. Check the fuel pump: You should hear a humming or buzzing noise when the fuel pump kicks in as you turn on the ignition. If you don't hear this, check your fuel pump relay, and verify that the electrical connections at the fuel pump are clean and secure.
3. Bleed the fuel lines: If air has entered the fuel lines, you will need to bleed them to remove the air and allow fuel to flow properly.
4. Check the fuel injector system: Check for any leaks or damage in the fuel injector lines, and make sure the fuel injectors are functioning properly.
5. Check the glow plug system: Since it's a diesel, the glow plugs should be in working condition for a successful cold start. Ensure they are getting enough power and that they're not faulty.
