Code P0171?

Hi,

If there are no vacuum leaks, the next thing to check is the fuel pressure. If the pump is weak, it can cause a lean fuel mixture.

Here is a link that explains how in general to check pressure:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If you look below, I attached the manufactures directions for testing specific to this vehicle. The directions include the pressure specifications.

You will need a fuel pressure gauge. Often times, a parts store will lend one to you if needed.

Let me know if this helps, if you have other questions, and what you find.

Take care,

joe

See pics below.