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-   -   Diagnosing P0171 system lean (https://chevroletforum.com/forum/venture-29/diagnosing-p0171-system-lean-115079/)

milehighxr Dec 16, 2023 1:42 PM

Diagnosing P0171 system lean
 
As I am diagnosing system lean, the manual is directing me to use a code reader to command the fuel pump on so I can do fuel pressure testing.

The code reader I have does not have this ability, so much for the discount code reader that was dirt cheap when I bought it...
So the question is, is there any way on this green earth that I can hot wire the fuel pump to run so I can do this testing? Most shops around here charge $130/hr+ for all labor. I think I can get a code reader that will turn things on and off for $300, maybe less. I spent $100 on the one I have now, and it uses the PC as the software, plus data logging, and live streams.

I have to pass smog nazis in 2 months, and the check engine light needs to be out with no codes stored or pending.

mountainmanjoe Dec 16, 2023 4:21 PM

put a gauge on the test port. Then turn the key to run position to turn on the pump and pressurize the system. monitor the pressure over 15 minutes.

Photon440 Jan 11, 2024 2:26 PM

Did you get your problem sorted? Like mountainmanjoe said, you don't need a fancy device to turn on the fuel pump; the ignition key will do that. You'll likely want the engine running anyway so you can test whether or not the pressure increases when you remove the vacuum hose from the fuel pump modulator.


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