Step 4: Final Testing & Results

After all repairs were completed, we went through a final round of voltage drop testing. The results:

• Old fuel pump fuse (before fix): 7V drop
• New inline fuel pump fuse (after fix): 0.25V drop
• Other fuse readings: Between 0.005V – 0.18V (perfect)
• Car starts immediately when cold—no more excessive cranking!

We took the car for a test drive, and as expected, there was no burning smell. The fuel system and electrical circuits are now working as they should.

Conclusion: A Reliable Fix for Voltage Drop Issues

By identifying and addressing the bad fuse connections and weak battery terminals, we completely resolved the electrical issues in this classic 911 SC. The burning smell is gone, the hard-starting issue is fixed, and voltage drops are within spec.

This process shows how voltage drop testing is the key to diagnosing electrical problems the right way—instead of guessing and throwing parts at the car. Now, this Porsche is back on the road, running as it should!

Next Steps: We’ll continue monitoring the electrical system, but with these repairs, the car is solid. If you’re dealing with similar issues, always start with voltage drop testing—it can save you time, money, and frustration.

Stay tuned for more classic car diagnostics and fixes!