hi everyone im new here just trying to get my wifes truck running right.... 2002 silverado 4.8 short cab and bed 114,xxx miles clean truck full tune up and service 1,000 miles ago new cats and o2 sensors 9,000 miles ago ...... reacently it had codes for bank 1 and 2 lean we changed ; mass air flow (maf), fuel pressure regulator, gas cap, and cleaned the throttle body............ and still the first start of the day only its hard starting and randomly the check engine light comes on with P0171 AND P0174 LEAN BANK 1 AND 2 any help would be awesome might it be the air idle control (aic)??

 

Was the fuel filter changed? If so may be time for a fuel pressure test.

 

Leaking intake gaskets - before you start up the truck (a cold start) prepare a garden hose near the truck and get it flowing. Start up the truck and pour water onto the area between the plastic intake and cylinder heads. If the truck stumbles and missfires, and blows white smoke from the tail pipe, you have hands down leaking intake gaskets causing a vacuum leak cold start lean condition.

 

thanks guys yes fuel filter was changed ill check fuel press. at the rail this weekend.......... ill check for vacuum leaks as well

 

ok i tested fuel press. and for vacuum leaks looks like its fuel pump time max press. was only 45psi and leaked down as soon as the truck was off i called around and the local parts store has 2 types one says its
With Evaporative Emissions
With Tag Code: TCF
Flow Rate (gph): 25 gph
the other is

Fits GM Tag Codes: TCU
One (4 Pin) Electrical Connector
Without Evaporative Emissions
Flow Rate (gph): 20 gph
how do i find out whitch one i need they look the same

 

It will be the number of plastic nipples on the top of the pump. I'd say most likely your truck has evaporitive emissions. Another way to tell is to call up a GM dealer with your VIN and get a part number for their pump, and ask them.

And if it were me, if I were to change out the pump, I'd only put a GM pump in there. If I'm going to go through all that work, might as well use a quality pump.

 

x2 on the GM pump. Might carry a lifetime warranty?