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  1. #1

    Default starting is rough, have to depress peddle slightly then shudder start

    hey all,

    my 97 yukon 5.7L suddenly starts acting up on start-up. always fired 100% now hit and miss as if throttle position sensor is not there. if i hear the fuel pump fire up then it usually is ok but seems like no idle kickup for start. press peddle slightly and usually with a snort and buck it will come to life. got home and pulled fuel pump relay and it was quite warm. any help would be great, thanks. p.s. when i checked auto parts for relays, surprisingly, they all listed continuous duty as NO. WHAT? a 3 hour drive seems like continuous to me

  2. #2

    Default

    Like you, I think a continuous duty relay should be used as the pump relay.........but, that would cost more.

    The intermittent duty cycle relay is cheaper and will normally last until the warranty runs out.

    It's warm, because it was being operated....that means, the relay coil is still good; however, it does not mean the contacts are any good. If the contacts are bad, the pump will not get power.

    Try a new relay (they're not expensive), and if you still have fuel delivery problems, it might be the pump, or perhaps the wiring.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  3. #3

    Default

    I think i might have lost part of the ecm? Is that possible? It all started while going down the highway at 60mph and the sel and abs brake light flashed rapidly and engine felt like it died, then smoothed out again and the sel and park brake lights were no longer on.(they should be on because of o2 sensor code and park brake is set to 1 click to keep headlights off). since that episode the idle wont kick up for start unless the engine is stone cold. no stored codes, as if it shorted out and cleared itself out. all the lights on dash will light up with key on as usual, but not while running. help anyone?

    - - - Updated - - -

    Quote Originally Posted by renegade1957 View Post
    I think i might have lost part of the ecm? Is that possible? It all started while going down the highway at 60mph and the sel and abs brake light flashed rapidly and engine felt like it died, then smoothed out again and the sel and park brake lights were no longer on.(they should be on because of o2 sensor code and park brake is set to 1 click to keep headlights off). since that episode the idle wont kick up for start unless the engine is stone cold. no stored codes, as if it shorted out and cleared itself out. all the lights on dash will light up with key on as usual, but not while running. help anyone?
    While under the hood, testing the temp sensor trying to get an ohm reading, with key off, i suddenly see sparks, smoke, and arcing sounds from lower engine passenger side!!!! wow! grabbed a wrench, pulled off the pos batt cable and climbed under to investigate this new issue. there is a heat shield on the starter that had rubbed its way through the starter cable and was shorting to the shield. I now realize that this is the culprit for these issues i have been having. explains the intermittent static i was getting on the radio too. I now believe that the ecm was getting stray voltage on the ground side and could not sort it out. May have partially fried the ecm, but it starts great now. I believe i was about a half hour from having a GMC bonfire in my driveway!! Next time you are under your truck, might be prudent to check this area out.

  4. #4

    Default

    How is it running now? Did you let it cycle a few times and/or check the battery to make certain that it's functioning?

    P.S. Reading a large block to text is pretty hard, especially when the most important information is stuck in the middle of a 10-line block of text. You'll get more responses if you break down your brick of text into smaller paragraphs. #justsaying.

    While under the hood, testing the temp sensor trying to get an ohm reading, with key off, i suddenly see sparks, smoke, and arcing sounds from lower engine passenger side!!!! wow! grabbed a wrench, pulled off the pos batt cable and climbed under to investigate this new issue.

    there is a heat shield on the starter that had rubbed its way through the starter cable and was shorting to the shield
    .

    I now realize that this is the culprit for these issues i have been having. explains the intermittent static i was getting on the radio too. I now believe that the ecm was getting stray voltage on the ground side and could not sort it out. May have partially fried the ecm, but it starts great now.

    I believe i was about a half hour from having a GMC bonfire in my driveway!! Next time you are under your truck, might be prudent to check this area out.

    Steve
    10 Chevy Traverse LT AWD
    02 Chevy Trailblazer LS (110K+ miles - loaded except for 4WD - WRECKED!)
    99 Chevy Cavalier LS (105K+ miles - commuter car)
    78 Chevy Suburban Silverado (454, 3/4 ton)
    62 GMC 3/4 ton Pickup (350 police interceptor)

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  5. #5

    Default

    What I would do is id check the fuel filter and also after i did that i would run some injector cleaner through it and see if that changes it and if it doesnt id go look at the fuel pump
    1994 GMC Yukon, 2 door, Victory Red
    Garage Link: http://www.gmtruckclub.com/forum/sho...1994-GMC-Yukon

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