Suburban Diesel Fuel Pump Issues: Warning Signs & Help

I had a similar issue with my 2021 Tahoe diesel. Let me share my experience, as I have some basic knowledge about diesel fuel systems. The symptoms you describe match what I experienced, rough idle, hard starts, and increased fuel consumption. Initially thought it was the fuel injectors, but turned out the fuel pump wasn't delivering proper pressure due to a faulty wiring connection. Got it fixed last month, the repair involved replacing a damaged connector and rewiring the fuel pump assembly. Total cost was 95 for the electrical repair, which was much better than replacing the entire fuel pump. Before you proceed with repairs, would be helpful to know: What error codes are you getting? Have you noticed any metallic sounds from the fuel tank area? Is the issue worse when the fuel level is low? has any fuel system maintenance been done recently? Testing fuel pressure would be the next logical step to properly diagnose if it's a pump failure or electrical issue. A proper diagnosis can save you from unnecessary parts replacement.

Finally got the diagnostic results back after the pressure test. The fuel pump is putting out inconsistent pressure readings, dropping well below spec under load. Tech confirmed it's not just a wiring issue like yours. Already had a recent service at 32402 KM, including a fuel system cleaning, so we ruled out contamination. Looks like I'm facing a full fuel pump replacement. The car performance really tanked after these symptoms showed up. Started getting P0087 and P0193 codes which also point to fuel delivery problems. Good tip about the fuel level test, definitely noticed it gets worse when under half tank. Guess I'll have to bite the bullet on the repair costs. At least caught it before it could damage the fuel injectors.

Thanks for the follow-up on the diagnostic results. Sorry to hear you're facing a full pump replacement, but it's good you caught it early. When I had my Tahoe's electrical issue, I was lucky, but fuel pump failures are pretty common on these models once they start showing pressure inconsistencies. Looking at your error codes and symptoms, especially the P0087 and P0193, you're definitely making the right call going for the replacement. These are classic indicators of fuel delivery problems that I've seen discussed in several automotive diagnosis forums. The inconsistent pressure readings under load are a dead giveaway, there's really no band-aid fix for that. The fact that your symptoms worsen below half tank actually makes perfect sense with faulty pump behavior. When my fuel delivery issues were happening, I also noticed similar behavior, though mine turned out to be that wiring problem. One tip from my experience with these diesels, while they're doing the pump replacement, might be worth having them inspect the fuel injectors just to be safe. Prolonged exposure to irregular fuel pressure can sometimes affect injector performance, even if they're not showing obvious signs yet.

Thanks for that detailed breakdown. The uneven fuel pressure readings really confirm what I was suspecting. It's frustrating to deal with fuel pump issues on such a new vehicle, but at least now I know exactly what I'm dealing with. I'll definitely take your advice about getting the injectors checked during the repair. Makes sense to be proactive since the fuel delivery has been inconsistent. The mechanic quoted about 8 hours labor plus parts for the complete fuel pump assembly replacement. Expensive fix, but beats having cascading problems from running it with bad fuel pressure. Hoping this solves all the issues, the rough running and stalling have made the truck pretty much undriveable. I've been avoiding long trips since the car performance is so unpredictable. Really appreciate the input about checking the injectors too. Will update once the work is done in case anyone else runs into similar fuel system problems with these newer diesels.