Code P0303

2001 GMC SIERRA
125,000 MILES • 4.3L • V6 • 2WD • AUTOMATIC
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JPHILLIPS120V
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pulling code p0303, replaced distributor and rotor, spark plugs and wires, crankshaft position sensor, fuel pump pressure tested at 55 PSI, replaced 02 sensor on bank 1 number 2. What else can I check?
Jan 22, 2021 at 8:29 PM
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SEVAG P
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Hello,

You have misfire at cylinder 3 refer to fault code p0303,that spark can be the problem, injector or low compression in that cylinder.

use our guide how to repair misfire.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Check for injector pulse.

https://www.2carpros.com/articles/how-to-test-a-fuel-injector

Check ignition spark at cylinder 3.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

If you have good blue spark and the injector is good, then you must check the compression of that cylinder and compare with others.

https://www.2carpros.com/articles/how-to-test-engine-compression

Let us know what happens with you.

Thank you.
Jan 23, 2021 at 9:30 AM