Chevy Silverado Lean Codes P0171 And P0174

Question:
About 6 months ago i had problem start the truck, like it ran out of gas,but i was half full. Took the car to my mechanic and he told me it could be one or two things bad - first the fuel pump was bad or two the fuel pressure regulator was bad or both. At this point i had no service engine soon lite on. IT held him to start with the easy and less expensive repair. He said it would be the fuel pressure regulator. 1998 Chevy Silverado 1500 4 - W 5.7 Vortec. Warning lights = check engine soon. Computer codes = P0174 Bank 2, P0171 Bank 1. Repairs made= New fuel pump - replaced fuel pressure regulator (FPR) - cleaned the mass air flow sensor (MAF), replaced fuel filter and o2 sensors.

The next day i picked up the truck and drove it home, about 5 miles i noticed the lite was on, so i went back to the shop to be told we would have to replace the fuel pump. So i had them do that. Pick up the truck drive it home, it is starting great at this time and then the lite comes back on the next day as i am driving to work.i go back,and he gives me a song and dance reason and now is telling me the fuel injector are bad and should be replaced. I ask him could the pressure regulator be install wrong since i did not have the lite issue prior to it's replacement. He got very defensive with me and said no.

Could that be the problem i am having.I have be driving my Chevy truck for the last three months and the lite go off on it's own and comes back on it's own. Sometimes for days staying off and than on for a day or two and than off again. At this point i do not want to pay for another guessing solution and that is what i feel that is happening. I when to a chevy dealer told him the story and he says it is the fuel injectors and it would be about two hundred each to replace them. Before i do that i am now trying to research the problem on my own before i jump in and do the injectors. Thanks for any help.

Answer:
Well, the codes you have are for the Fuel Trim being lean. That means that the fuel mixture does not have quite enough fuel to create the best burn in each cylinder. Too much air will lean out the cylinders and cause the oxygen sensors to read incorrectly.

They will be telling the computer to richen the mixture up but something is keeping it from doing that. Usually, the fuel pump is main cause. Low fuel pressure or lack of volume from a worn out pump is a prime candidate to cause a lean code. A clogged fuel filter is another big one.

With the pump and regulator being new, I would doubt your problem lies with either of those. If you haven't changed your fuel filter, I would start with that since it's pretty easy. The fuel injectors can cause a lean condition when they get dirty or stick from debris or other build up. A fuel injector cleaning might fix you up, and that's an easy one to do, too.

If they do need replaced, it is always best to replace them all at one time, even though it would be expensive.