Question about 2003 GMC Sierra 1500

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2003 GMC heavy half with 6L. Fuel pump problem

2003 GMC heavy half with 6L. Engine has a long crank time so I thought it was maybe the check valve on fuel pump. Let it sit for about an hour, pushed in the shreadder on fuel rail and no fuel came out. So that leads me to believe it IS the check valve on pump, Can you clean that valve at all like running sea foam through system or injector cleaner? Don't want to buy a new pump!!

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  • 3 more comments 
  • sanger131654 May 17, 2010

    riceski was great! But the problem still is there but his advice helped!

  • sanger131654 May 17, 2010

    Problem still there. Ran sea foam through and it still don't wanna start after awhile of sitting.. Any other ideas

  • sanger131654 May 17, 2010

    Here is how bad my luck is. I just bought the truck about a month ago with no warrenty. But it is wierd because i let it sit all night this weekend and sunday morning i went to start it and i forgot i had to prime the pump ( turn the key and let sit for a few seconds to prime line) and i turned the key to start and it didn't miss a beat! Started right up. But later that day after it was sitting, i pushed in the shreader valve and no gas came out. SO! i guess the sea foam is not working. Could this be a filter issue?? Or if it IS the pump check valve, do they make a cheep inline type valve i can throw in for now until i get the money to fix??



    Thanks

  • sanger131654 May 17, 2010

    Is there a way i could take the pump out and back flush the pump? To see if i could un jam it?

  • sanger131654 May 18, 2010

    Is it like a steel ball or is it a one way flapper? Would pounding softly on the pump while its still in the tank work? ( only asking cause if it's a ball that lifts up, hitting the thing might drop it...)

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  • GMC Master
  • 1,851 Answers

Yes - Seafoam used properly can alleviate the problem. Seafoam used wrongly can do more harm than good so follow the instructions. While you at it - take down the vin number and call the dealer nearest you and ask about RECALLS - this can save you a lot of headache. Matter of fact call two dealers - just to be sure.
Best of it

Posted on May 13, 2010

  • 3 more comments 
  • sanger131654 May 13, 2010

    Well it treats 8-25 gal. Im at about 3/4. Will that be ok if i add the whole pint?

  • Gary Rice
    Gary Rice May 13, 2010

    YES - that is fine - just don't do anymore.
    Keep me posted as to how it comes out.
    Please rate me helpful - it really makes a difference.
    Thanks
    Gary


  • Gary Rice
    Gary Rice May 17, 2010

    Thanks for the good words - Now back to the problem. There are several things that
    come to mind. When is the last time you had a tune up - changed the fuel filter - air filter and plugs? There are
    many more electrical things that can go wrong and not be caught in an analysis from where I sit. SO- -
    I am suggesting you get a GOOD fire extinguisher and run the truck for about 3 minutes - then shut it off and try
    the fuel line pressure. Try to keep all fuel away from exhaust but even if a little gets on there it isn't the end
    of the world but it is way better to be safe. If you do this [ I do recommend you take it to a professional unless
    you are super comfortable] then check the fuel pressure right after shut down. If it is up - way up - replace
    fuel pump and filter. Sadly this is about all you can do at this point.
    Please keep me posted.
    Gary



  • Gary Rice
    Gary Rice May 17, 2010

    Due to the computer there is little to do but to live with it for now. You might try priming it with ether or WD40 as a starting fluid.
    I do wish you the best but with the computer in the mix your restricted as to what you can add or remove and still have a functioning truck.

    Gary


  • Gary Rice
    Gary Rice May 17, 2010

    Yes you sure can - pull it and at least inspect.

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