bad fuel pump cause p0171 and p0174?

[xz96]

So I scammed my truck today, got two code0171 and p0174.
Did some research, found out some common possible cause:
Dirty maf sensor
Vacuum leak
Manifold intake sensor

But my fuel pump went bad and it was replaced 10 days ago.. Could a bad fuel pump caused the code? I had about 600miles on the new fuel pump.

My mpg is fine, about 20 on highway. Truck runs fine as well..I don't know if the mechanic reset the code after he replaced fuel pump, my guess is he didn't.

Does code disappear by itself after repair?

I know how to clean maf sensor but how do I check vacuum leaks?

 

[xz96]

Hmmm I just found answers from this thread:http://www.explorerforum.com/forums/showthread.php?t=262711

If anyone is having same problem

 

[koda2000]

Hmmm I just found answers from this thread:http://www.explorerforum.com/forums/showthread.php?t=262711

If anyone is having same problem

i've read where others have reported this. i guess if your filter is really clogged (and they can get really clogged if not changed regularly) this could happen. it's an easy thing to try first, but if that doesn't solve the problem those codes usually indicate a vacuum leaks (hoses and/or intake manifold gaskets or even the PCV grommet or brake booster). those codes indicate too much air and not enough fuel in the engine's combustion.

 

[xz96]

i've read where others have reported this. i guess if your filter is really clogged (and they can get really clogged if not changed regularly) this could happen. it's an easy thing to try first, but if that doesn't solve the problem those codes usually indicate a vacuum leaks (hoses and/or intake manifold gaskets or even the PCV grommet or brake booster). those codes indicate too much air and not enough fuel in the engine's combustion.

Filter was replaced like 6 month ago. I used another obd2 device, it's weird that no code was found.. Do you know what's the normal range for short term fuel trim and long term fuel trim? My stft is from -6 to 5.. Ltft is from 7 to 13..i ll go to AutoZone to try their obd device..