Very Poor Fuel Economy, Speedometer bouncing all over or not working at all

Discussion in 'GM Powertrain' started by Gigantor, Nov 3, 2012.

  1. Gigantor

    Gigantor New Member

    Hello Forum,

    1994 Suburban, K2500 7.4 454 146,xxx miles

    I am having 2 different issues. First, I am getting very bad fuel economy. 7 to 9 miles per gal. I am looking to upgrade my fuel system. I am wondering if there is an aftermarket system that can go on my truck or is it better if I switch to a carb system. Then I would have to change over a lot of electronics.

    Second, my speedo is all over the place. 2 speed sensors have been replaced already, by the dealership. For this problem I am stumped.
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    when was the last tune up? plugs, wires, cap rotor, fuel and air filters? The speedo issue could be a bad stepper motor in the instrument cluster.
  3. Gigantor

    Gigantor New Member

    I did a complete tune up 5 months ago. Today I noticed the speedo also does not work when its cold outside, Go figure.
    I was looking at the Holley Commander 950. as an upgrade.

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