Codes P0171 and P0174?

VERAMATT

MEMBER
2003 CHEVROLET SILVERADO
4.3L
V6
2WD
MANUAL
275,000 MILES

Codes p0171 and p0174 until I reach 110km/h. Then it starts to lose power and won't climb even the slightest hill. Downshift to 4th, throttle to the floor, still losing speed. Clear the codes (code reader stays plugged in) and engine power is restored but only for 1 or 2 seconds if I keep my foot to the floor. Longer if now downhill and little throttle is used. Now p0131, p0137, p0151, p0157, p0171, p0174 all at once. Haven't been over 130kmh (couldn't when I wanted to) with this truck since I owned it.

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
47,643 POSTS

The P0171 and P0174 trouble codes on a 2003 Chevrolet Silverado indicate that both banks of the engine are running too lean. The main reason for this to happen is low fuel pressure, which is common on these trucks, here is a guide to help us confirm the issue and you can rent a fuel pressure gauge from the local auto parts store for free or cheap.

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

and this guide may help as well:

https://www.2carpros.com/articles/engine-has-low-power-output

Fuel pressure - 55 to 62 PSI.

Here is how to change out the fuel pump if the pressure is low. Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

Images (Click to make bigger)