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Eric, Automotive Repair Shop Manager
Category: Chevy
Satisfied Customers: 32102
Experience:  20+ yrs. experience as repair shop manager and technician.
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2000 Chevy Blazer: vortec..intermittent..maf sensor..po171..too lean).

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Hello, I have a 2000 Chevy Blazer with 4.3L Vortec Eng. Here's the problem(s): The Check Eng light is intermittent with a codes PO101 (MAF sensor) & PO171 (Sys. too lean). Also the fuel pump is making a very high pitched sound and the truck hesitates on acceleration with the engine cold. Could all these problem be related to the fuel pump? --- Thanx in Advance,Customer



While the lean code can be caused by a faulty MAF sensor and/or weak fuel pump, a MAF sensor code wont be caused by a weak or faulty fuel pump.


Lean codes are generally caused by a vacuum leak, weak fuel pressure, intake air leak, faulty or dirty MAF sensor, or intake manifold leak.


MAF codes are generally set by a faulty MAF sensor, vacuum leak, faulty PCV valve, open or short in MAF sensor wiring harness or connector.


First, check for vacuum leaks, including the intake manifold and throttle body. Spray around base of intake manifold with carb cleaner while engine is idling. If idle changes, replace intake manifold gasket.


If no leaks, then perform the following tests to determine whether MAF sensor is bad, or a wiring issue:



Click to open and download> Fuel pressure test


Eric and other Chevy Specialists are ready to help you
Customer: replied 8 years ago.
Thanx Eric,
I know what to do now... time to get to work! Wink --- Peace,Customerbr />