Here's the dirty little secret about your diesel: the stock lift pump in your tank was built to the absolute bare minimum it could be and still leave the factory. It's not designed to feed a tuned engine, it's not designed to filter water and air worth a damn, and...

Let's not sugarcoat it: there's a relatively cheap part bolted to your late-model diesel that's quietly waiting to detonate a $12,000 repair. It's the Bosch CP4.2 high-pressure fuel pump, and when it grenades, it doesn't ask permission — it machine-guns metal shrapnel through your entire fuel system and leaves you...