Dirty 30

iTrader: (97)

My friend has a 2003 Silverado SS AWD bone stock with only a K&N OE replacement filter (stock tune as well). Its throwing a code P0101, P0171, and P0174. I logged it and sometimes it gets knock retard and sometimes it doesnt. I cleaned out the MAFS with MAFS cleaner but still runs the same. the CATS where replaced about 1 month ago as well but didnt help any. I also sprayed some carb cleaner around the vacuum connections and around the intake ports to check for vacuum leaks but didnt surge or anything.

I also checked the fuel pressure and at idle its 44 psi. At part throttle, it goes up to 50 psi. At wide open throttle, it shoots up to 56 psi and no more. When I turn it off, the fuel pressure goes down to 0 psi in about 2 minutes. I replaced the fuel pressure regulator on the fuel rails but still the same. I also replaced the fuel filter just in case.
Any help is appreciated!
-Jesse


(included are 2 logs)

GMCtrk

iTrader: (27)

03 should still be the return system right? If so, you should be seeing 55 psi at idle. If it's returnless it should be a constant 58-60 psi.

Dirty 30

iTrader: (97)

yes, its return style fuel rail.

GMCtrk

iTrader: (27)

Well it sounds like you need a new fuel pump. I'd stop driving the truck and replace it. It's not pretty when it goes out on the street like mine did. Truck just flat out died while driving.

Dirty 30

iTrader: (97)

Hmm... Would that cause P0101 to pop up?

GMCtrk

iTrader: (27)

that KN filter if it's oiled might be throwing oil onto the MAF

Dirty 30

iTrader: (97)

The filter is dry and I already cleaned the MAFS.

Truckshop

iTrader: (17)

looks like the pump is weak. you can get a p0101 if it stalls.

Dirty 30

iTrader: (97)

Do these return style trucks have another fuel pressure regulator in the gas tank?

Would a weak fuel pump cause the fuel pressure to go down to 0 after turning the truck off for 2 mins?

Again, thanks for the help guys! I read thru atleast 20 old threads and everyone seemed to check the same stuff like I did but at the end, no one reported back what the problem was for them.

Dirty 30

iTrader: (97)

When i reset the fuel trims at idle (they were at +25%), the truck runs very lean and hesitates. I left the fuel trim learn OFF and closed loop OFF and it runs lean as well.