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98 Chevy 5.7 bogging out

Discussion in 'Chevy Trucks' started by Timothy Logan, Mar 20, 2020.

  1. Timothy Logan

    Timothy Logan Junior Member
    Messages: 5

    I have a 1997 chevy 1500 siverado with a 5.7 vortec that has been having a problem for about 6 months now. The truck starts, idles, and revs normally and when accellarating slowly everything works just fine, but once you get past half throttle it falls on its face and acts like it has a clogged fuel filter or bad fuel pump. It actually goes slower than below half throttle. The bogging gets consistently worse the more throttle you give it. I have replaced everything that I could think of, as well as everything many chevy guys have suggested. here is a detailed list of everything replaced in the last 6 months. (Distributor cap, rotor, plugs(twice), plug wires(twice), fuel filter(twice), fuel pump, fuel pressure regulator, both O2 sensors, fuel injectors cleaned).I have also checked the fuel lines for kinks, crimps, and leaks and found none. I have also unbolted the exhaust and run the truck to check the Cat for clogs, but it ran the same. The most confusing part of the whole thing is there is no check engine light on, so i have no way to check it on a computer. My friend looked at the spark plugs and noticed a little brown on them which he said might be caused by it running lean. Any ideas you could give me of what to change or check would be greatly appreciated.
  2. seville009

    seville009 PlowSite.com Addict
    from CNY
    Messages: 1,734

    Even though there’s no check engine light on, should still check for codes (unless the older trucks don’t throw codes without triggering the cel)
    Randall Ave and Avalanche 2500 like this.
  3. Avalanche 2500

    Avalanche 2500 Senior Member
    Messages: 856

    Clean throttle body intake/ mass air sensor w/ appropriate sprays, air filter cabin clogged ?? :drinkup:
  4. CHPL

    CHPL Member
    Messages: 85

    Disconnect the vacuum line to the egr valve and drive it. The solenoid that controls it may be bad.
  5. Randall Ave

    Randall Ave PlowSite Fanatic
    Messages: 10,907

    Did you put a vaccum gauge on it while driving, Clean the mass airflow sensor. You need a good proffesional scanner to check it.
  6. maxwell1027

    maxwell1027 Member
    Messages: 81

    Clogged EGR valve.
  7. OP
    Timothy Logan

    Timothy Logan Junior Member
    Messages: 5

    Fixed even though I had no check engine light on I put on scanner and erased all stored codes it had 8 drove like a champ put scanner back on it and no codes
  8. TJS

    TJS PlowSite.com Addict
    Messages: 1,838

    This happened to me with my 98 Tahoe. I did in fact have a bad fuel pump. Replaced it with some buffalo brand. Worked good for a while. Then when the weather got warmer it did the same thing. Fuel pressure test while driving and what do you know another bad pump. Replaced it with AC/Delco pump (which is not saying much) but it was good for many years after that. Till the backhalf of the frame rotted out.