99 Silverado P0171 / P0174
The other day my mostly stock 99 Silverado set off code P0174. There were no noticable changes in the way it drove and it is not idling rough. I cleared the codes to see if it would come back and the SES light came back on today. This time I got P0171 and P0174. I hooked up my fuel pressure guage and key on engine off it read 53 psi. I know that is a couple psi low from where it should be. With the engine running the fuel pressure dropped to 50 psi. After shutting the engine off it maintained pressure at about 45 for well beyond 5 minutes. I had originally read that a dirty MAF could cause this issue, but with the fuel pressure reading being lower than it should be I was thinking fuel filter or pressure regulator. Any thoughts? Thanks for any help.
Last edited by IORCET; 12-31-2009 at 01:05 PM.