Identifying the Leak:
* Location: Pinpoint exactly where the leak is originating. Is it from the pump itself, the connections (inlet and outlet lines), or the seals/gaskets? A picture would be incredibly helpful.
* Severity: Is it a slow drip, a steady stream, or pouring out? A slow drip might be manageable for a while, but a significant leak requires immediate attention.
* Fuel Type: Make sure it's actually diesel fuel leaking and not something else.
Possible Causes and Solutions:
* Worn-out Pump: The pump itself may be failing due to age and wear. This often manifests as leaks around the pump body. Replacement is usually necessary.
* Loose or Damaged Connections: Check all fuel lines and clamps connecting to the lift pump. Tighten loose clamps, replace damaged lines, or repair any cracked or broken connections.
* Failed Seals/Gaskets: The pump uses seals and gaskets to prevent leaks. These can degrade over time. Replacement might be possible without replacing the entire pump, depending on the accessibility.
* Cracked Pump Housing: A crack in the pump housing will require replacement of the entire pump.
Troubleshooting and Repair:
1. Safety First: Diesel fuel is flammable. Work in a well-ventilated area, away from open flames or sparks. Wear safety glasses and gloves.
2. Visual Inspection: Carefully examine the pump and surrounding connections for any obvious leaks or damage.
3. Pressure Test (Optional): If you have the tools and knowledge, you can perform a pressure test on the fuel system to pinpoint the exact location of the leak.
4. Repair or Replacement: Based on your findings, you can either repair the pump (replacing seals or gaskets) or replace the entire pump. Replacement is often the more practical solution, especially if the pump is old.
5. Parts: You'll need to find a replacement lift pump for your specific 1991 Dodge diesel model. Parts stores or online retailers specializing in classic Dodge trucks will be good resources.
Important Considerations:
* Year and Engine: Specifying the exact year and engine model (e.g., 12-valve Cummins) will help in finding the correct replacement parts.
* DIY vs. Professional: Replacing a fuel lift pump can be done DIY with the right tools and mechanical skills. However, if you're not comfortable working on your vehicle's fuel system, it's best to take it to a qualified mechanic. A leaking fuel pump can lead to serious running issues if ignored.
Without more information (pictures, type of engine), this is the best general advice I can offer. Provide more details, and I might be able to give more specific guidance.
