99 suburban fuel pump

Discussion in 'Shop Talk' started by centexguy, Dec 15, 2006.

  1. centexguy

    centexguy Well-Known Member

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    I have a new mechanical problem. My 99 suburban is dieing at very random intervils. It will run fairly well for weeks or months then completely die suddenly like you shut off the ignition. The fuel pump has been making a high pitched whine for some time. I have noticed that when you floor the gas
    it shudders like its not putting out enough fuel pressure.( it showed about 50psi at highway speed with a gauge) The truck shows no codes no check engine. I have replaced recently;fuel filter, plugs, wires, dist cap, rotor, pickup coil. It could possibly be the fuel pump relay or the ignition module. :shrug: anyone have any other ideas? The fp is $265+ and I know a module is pricey as well.
     
  2. Herb

    Herb Well-Known Member

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    If you are getting 50 psi, I would say the fuel pump isn't the problem.
     

  3. cfabe

    cfabe Well-Known Member

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    Do you maintain pressure at full throttle?
     
  4. fixer1958

    fixer1958 None of the Above

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    Check the spec on FP pressure. A Vortec has to be within the margin to run
    +or- whatever it is. 50 psi sounds a little low to me. The bushings in those can sometimes get hot and quit and be ok after it cools. Whining is a good indicator. The only other major malfunction I can think of is the distributor itself.
     
  5. mightybooboo

    mightybooboo Well-Known Member

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    Either way,that FP is telling you its time is up.

    Here you go....Is this you?
    ----------------------------------------------------------------------
    The GM Vortec CSFI (central sequential fuel injection) system requires 60 to 66 psi of fuel pressure, so you'd expect to see roughly 6 to 8 amps of current flow to run the pump. Significantly higher current flow indicates a tired pump.
    ----------------------------------------------------------------------

    BooBoo :gromit:
     
  6. fixer1958

    fixer1958 None of the Above

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    Most any GM SUV or PU fuel pump will make some noise. Mine has been bitching for 2 years and no problems. Worse some days than others. Kind of a monthly cycle. Just hold your head down and hope for the best, it may pass if you know what I mean. Just be aware of telltale signs.
    Missing on hard acce
    eration etc. You have to determine though if it is cry for help.

    There is some correlation between your spouse and your truck sometimes. Give it what it needs and talk to it nice and things usually work out without to many scars that show. It can be kind of hard sometimes to see what the problem is, but once you do your home free.

    I have issues. I know that!
     
  7. tiogacounty

    tiogacounty Well-Known Member

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    Not sure what the issue is, but pump whine in GM's case can be a red herring. I have had three pumps in my '01 Burb. The first one was dead quiet until it puked, the second one was defective from the factory, so it only was in for a few weeks. The last one whines like a dentist's drill, and works fine. I think it's absolute BS that it should make that much noise, but the dealer claims it's working fine and within spec. Between this issue and all the plastic trash that constantly breaks in the interior, I have to say, "like a rock, my -----".
     
  8. moopups

    moopups In Remembrance

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    There is usually an 'impact trip device' located somewhere, its purpose is to shut off the fuel flow if there is a wreck. Check the wiring to it, look for burnt sections. Especially the connectors area. You can normally hear it click when you first turn the key if its located inside the cab.
     
  9. Cabin Fever

    Cabin Fever Life NRA Member since 1976 Supporter

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    The fuel pump in my '99 K1500 has whined since it was brand new. GM fuel pumps always whine. If they don't whine, they're dead!

    My first pump went after about 100,000 miles. I'm on my second pump and the truck has 190.000 miles now. The fuel pumps on GM trucks are a chronic problem (based on the experiences of many friends and acquaintances). Usually they work fine one day and then die and won’t pump at all the next day. I’ve never heard of one “slowly” dying.