• Tiny
  • seaya97
  • 2002 Chevrolet Avalanche

Engine Performance problem
2002 Chevy Avalanche V8 Four Wheel Drive Automatic 245000 miles

My "New" fuel pump squeals even with 1/2 tank of gas. With the gas cap tight, there is a "Extreme" vacuum created in the fuel tank. The Squeal is reduced when the vacumm is vented through the gas cap and I can can hear alot (I mean Alot of Air) of air rushing into the tank. I changed the cap and have the same problem. Codes that I have seen are (1) bank 1 to Lean (2) bank 2 to lean (3) Random misfire (4) Evap sys.
Should I be looking for a blocked line or EVAP canister?


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have the same problem?
Thursday, January 28th, 2010 AT 5:21 PM

1 Reply

  • Tiny
  • Service Writer
  • Expert
  • 9,254 posts

What code number is the EVAP code?
Not enough fuel is getting to the engine creating the lean and miss codes.

A restricted or blocked evaporative emission (EVAP) vent path is detected by the control module monitoring the fuel tank pressure (FTP) during normal operation. The control module commands the EVAP vent valve OFF, or open, and the EVAP canister purge valve ON, or open. The fuel tank pressure should remain low as vacuum is drawn on the EVAP system. If the vent path is blocked or restricted, the vacuum level will increase and DTC P0446 will set.

There may be a damaged EVAP vent housing, a blockage at the EVAP vent valve inlet, or a pinched vent hose.
IF this condition started right after the pump installation I would be looking for a pinched vent hose.

*A blockage in the vent system will also cause a poor fuel fill problem

Was the fuel filter replaced? If not do it ASAP.

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Thursday, January 28th, 2010 AT 7:52 PM

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