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Fuel pump delays to turn on

Discussion in 'GM Powertrain' started by silverado00, Aug 1, 2010.

  1. silverado00

    silverado00 New Member

    I have a 2000 chevy silverado 5.3l and a couple days ago it wouldnt start, I got it figured out that its the fuel pump. truck runs great while running but sometimes i have to turn key on and off like 3 times before i hear fuel pump kick on then i start it and its ready to go. i replaced fuel pump 50k ago. What do you think???
  2. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    I think that it sounds more like something in the fuel pump wiring than the fuel pump itself. It's been a while since I've looked at the fuel pump circuit wiring diagram, but I think I'd probably start at the fuel pump relay and see if, on those occasions when the pump doesn't immediately kick on, the relay is closing or not.
  3. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    X2.. Definately seems more like a wiring problem.
  4. silverado00

    silverado00 New Member

    i changed out relay no luck. When i turn the key offf and on 3 times real quick it works like a charm every time. I was having ignition problems before and had it replaced. when it locked up, Maybe the ignition is causing a problem. again.. Cause on the 3rd turn it always works consistenly.
  5. MrShorty

    MrShorty Epic Member Staff Member 5+ Years 1000 Posts

    Now that you've changed the relay, we'll assume the relay itself is ok. Have you checked to see if the relay is closing? Is the PCM sending the command to the relay to close? Where you say you've had ignition switch troubles before, and the PCM (which is responsible for commanding the fuel pump relay to close) gets its power through a circuit controlled by the ignition switch, I would be tempted to check to see if the PCM is getting power.

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