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2000 Chevy Express 1500 5.7L Fuel Pump Failure & P0452 Evaporative Emission Code Diagnosis

Model: 2000 Chevy Express 1500 Fault Code: P0452 Posted: 2011-05-10 12:28

Hi everyone, I'm experiencing a recurring issue on my 2000 Chevrolet Express 1500 with the 5.7L engine. Over the past two years, I've replaced the fuel pump twice—both failures appear to be linked to elevated fuel tank pressure. The vehicle is now displaying OBD-II diagnostic code P0452: Evaporative Emission Control System Pressure Sensor Low Input. During a recent long drive through Wyoming, I noticed a strong gasoline odor and had to stop immediately. When I removed the fuel cap, gas fumes erupted violently—lasting about six minutes—and it felt like a geyser. My mechanic replaced the pump but couldn't identify the root cause. Now I'm considering tackling this myself. I'd like to know: What specific components should I inspect? Where is the evaporative canister located in this model? Is there a known vent valve or hose that could be clogged, especially under high ambient temperatures (above 85°F)? I've observed significant pressure buildup in the tank when it's hot—sometimes even bubbling—which makes me suspect an evaporation system failure. Any guidance on diagnosing and fixing this would be greatly appreciated. P.S.: The issue seems to worsen above 85°F, and fuel efficiency has dropped from around 12 MPG to just 9–10 MPG recently.

Related fault codes
P0452
Comments (4)
Anonymous 2011-05-10 17:29

The most likely culprit is a clogged vent valve or obstructed hoses that release pressure during refueling. Refer to your Haynes manual for the exact location—typically behind the fuel tank, near the evaporative canister. While P0452 indicates an evaporation system issue, it's unlikely this directly causes your repeated fuel pump failures. Those are more likely due to poor-quality replacement pumps or faulty connections at the pump itself.

Anonymous 2011-05-10 19:27

Thanks for the insight—appreciate it! I'm going to start with checking the vent valve and canister system this weekend, then move on to fuel pressure and compression testing if needed.

Anonymous 2011-09-15 13:52

I've recently picked up three additional codes: P0158 (O2 Sensor Circuit High), P0404 (EGR Valve Stuck Open), and P0304 (Cylinder #4 misfire). I'm currently testing fuel pressure, cylinder compression, and overall engine performance. The gasoline smell has been persistent for some time now, and my mileage has dropped to 9–10 MPG. I'll update with results once I've completed the diagnostics—any feedback is welcome! Thanks, Beany

Anonymous 2011-09-15 16:46

Just a quick note: consider starting a new thread for your additional codes and engine performance issues—it might get better attention than hijacking this existing one, especially since the original issue here focuses on evaporation system pressure.