* Water in the fuel: This is a very common problem with diesel engines. Water settles in the bottom of the tank and can be drawn into the fuel system, causing poor starting and potentially other issues. The filter may temporarily remove the water, but it will eventually re-accumulate. Consider:
* Fuel tank drain: Does your tank have a drain valve at the bottom? Draining a small amount of fuel can help determine if water is the culprit.
* Fuel system additive: Using a fuel system water remover/treatment additive might help.
* Clogged fuel pickup tube: This tube draws fuel from the tank to the filter. Sediment, rust, or debris can clog it, restricting fuel flow. This is especially likely if the problem reoccurs quickly after a filter change.
* Failing lift pump (fuel pump): The lift pump is responsible for drawing fuel from the tank and delivering it to the engine's high-pressure injection system. A weak or failing lift pump won't provide enough pressure to overcome restrictions elsewhere in the system. This is a prime suspect given your symptoms. Listen carefully for a weak humming sound from the lift pump when you turn the key to the "on" position (before cranking).
* Restricted fuel lines: Similar to the pickup tube, fuel lines can become clogged with debris over time.
* Faulty fuel filter cap: Though less likely, if the fuel filter cap isn't sealing properly, air can enter the system, disrupting fuel flow and causing hard starting.
Troubleshooting Steps:
1. Fuel filter: Make absolutely sure you're using the correct fuel filter. Using the wrong one can lead to issues. Consider using a quality brand filter.
2. Water in the fuel (again): Drain a small amount of fuel from the tank. If you see water, this is a highly probable cause.
3. Lift Pump Test: Have a mechanic or use a fuel pressure gauge to test the lift pump. This will give a definitive answer on whether it's functioning correctly. Low pressure indicates a problem.
4. Visual Inspection: Inspect the fuel lines and pickup tube for any visible damage or blockages. This is a relatively simple, preliminary step.
5. Professional Diagnosis: If the above steps don't identify the problem, taking your truck to a qualified diesel mechanic is the best option. They have the tools and expertise to properly diagnose and repair complex fuel system problems. They might use a scan tool to check for any fuel system-related trouble codes.
Don't keep running the truck with intermittent starting problems. This can cause significant damage to the fuel injectors and other components. A proper diagnosis and repair are essential.
