The Booger That Broke the Beast

Using instrumentation to drive the fix

One day, my truck just… stopped pulling. It idled fine, but pressing the gas actually made it weaker. Something was definitely wrong with my engine

Fortunately, I’d installed a wideband O₂ sensor. The Air-Fuel ratio at idle was the same as always, but leaned out to 26:1+ as you pressed the pedal. Also, If you floor it, it only ran on a few cylinders but read 16:1 (14.7:1 is a normal reading)

Seems like the secondary jets are still operational, and the idle circuit is the only thing holding the engine up. This points to something clogging the main jet

I limped the truck home, either feathering the throttle or flooring it with no in-between, and tore into the carb. As I disassembled it, I found the culprit:

I'm not sure what that is, but it shouldn't be in there! After cleaning it out and reinstalling the carb it's pulling strong again!

Lesson learned: Instrumentation is critical for data driven decisions. It’s the difference between panic and precision.