What are some common problems with the fuel system on this model?

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The 1980 BMW 320i E21 model is known for a few common fuel system issues, primarily tied to its **K-Jetronic fuel injection system** (used in early E21 models). Here are the most frequently reported problems:

1. **Fuel Pump Relay Failure**:  
   - The fuel pump relay can degrade over time, leading to intermittent fuel delivery. This often causes hard starting or stalling.

2. **Fuel Pump Issues**:  
   - The electric fuel pump may fail due to age or electrical faults. Testing fuel pressure is a common diagnostic step.

3. **K-Jetronic Fuel Injection Quirks**:  
   - The K-Jetronic system is sensitive to fuel line blockages, clogged nozzles, or improper tuning. Vacuum leaks can also disrupt the air-fuel mixture, causing rough idling.

4. **Fuel Line Corrosion**:  
   - Older rubber fuel lines can crack or rot, leading to leaks. This is especially common in vehicles stored for long periods.

5. **Carburetor Tuning (if modified)**:  
   - While the stock E21 320i uses fuel injection, some modified versions (like the one you’re viewing) might use carburetors, which require precise tuning and are prone to fuel delivery issues if not maintained.

### Recommendations:
- For stock K-Jetronic systems, inspect for vacuum leaks and clean/injector service.
- If the fuel pump relay or pump is faulty, replacement is typically required.
- Classic.com markets for BMW E21 parts are limited, so consider specialized forums or vintage BMW mechanics for repairs.

Let me know if you'd like help finding repair guides or parts!

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