Fuel problem

Discussion in 'General Tahoe/Yukon/Escalade Discussion Forum' started by Classicman69, Sep 4, 2019.

  1. Classicman69

    Classicman69 New Member

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    Sep 3, 2019
    My name is Robert I have a 04 tahoe 2wd,it has new altenator and new battery and full tank of gas.it shut off on me 5 times last week but now it's doing it alot more.im am getting P0171and P0174 running to lean.when the motor shuts off it starts up right away,sometimes it'll run smooth and sometimes rough.i can have it parked idling for a very long time and I won't die.in the morning I can drive it for about half a mile before it dies,then after that it'll run for about 45 seconds then die and keeps repeating that cycle.O2 sensor short term fuel trim bank 1 sensor 2 is reading 99.2% and the voltage fluctuates from 100volt to 820volt and bank 2 sensor 2 is reading 99.2% and the voltage fluctuates from 100volts to 820 volts.long term fuel trim bank 1 and bank 2 are at 25%.my question is will these O2 sensors cause my fuel pump to turn off?I haven't done a pressure test on fuel rail but I'll be doing that later on today and I will post my findings.
  2. raiderron

    raiderron Full Access Member

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    Nov 8, 2014
    First thing I thought of was the fuel pump. If you can then attach a long enough hose to the fuel rail and worm the gauge out under the hood and tape to windshield and watch fuel pressure while driving in the same scenarios you stated. I have never heard of any O2 sensor shutting down a fuel pump. The sensor is reading exhaust and even if the system was bad enough where you eventually clogged a muffler the fuel pump will continue to pump fuel.