Single Mother Here...please help!!!

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Scarbreaux, May 29, 2010.

  1. Scarbreaux

    Scarbreaux New Member

    I could really use input as to what the problem could be regarding my '02 Flex Fuel Suburban. Over the last year I have been having issues with it shutting off on me while driving. I wait about 20 seconds and it will start right back up. It acts as though the fuel supply is being cut off. I have had the fuel filter changed twice in the last year and it has helped. However it started doing the same thing earlier this week, my commute home is about 70 miles and it shut off about 10-12 times and each time with each time it took even longer before it would start. I had the fuel filter changed Wednesday but 2 days later and its doing the same thing.

    I was told that I have 2 fuel filters....true or false. If true where are they both located?

    Would a bad Catalytic Converter cause it to act this way?

    Any insight would be much appreciated.
  2. phoebeisis

    phoebeisis Epic Member 5+ Years 1000 Posts

    You came to the right place.

    In general -rule of thumb-
    3 reasons a motor quits running

    1)Too little fuel-good bet in your case
    2)No spark- possible,
    3) Too little compression- no way in your case

    1) Too little fuel, can mean plugged filter,and someone here will chime in about the location of second filter.It can also mean a bad fuel pump, or problems with the electrical stuff that makes the pump, pump.It could also mean you somehow got some "bad gas" which usually means water in gas.Possible-maybe try to add lots of the additive that dissolves water in fuel-STP and others make it.
    I wouldn't refill your tank with good gas-not just yet.You might have to drop-remove- your tank and more fuel in it makes that harder-one gallon weighs 6 lbs or so-40 gallons 250 lbs or so.

    2)The no spark-there are some things-anti theft devices in ignition and such that suddenly cut the spark-possible, but I think the no fuel is most likely.

    After you find out about the second filter, you need to find out what your fuel pressure is. You will need a mechanic with a tool to measure this.

    Anyone out there-where is the second filter?
    1 person likes this.
  3. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    If it was a catastric failure of something you would have a computer code stored as why the computer shut the truck off and most liikely the truck wouldnt start again until the computer was checked for why it shut the truck off. So a fuel pressure issue would most likely be the culprit, it could also be the fuel pump too but that is more of a start up issue, once the truck is running they tend to keep doing there job.

    If there is a cat issue the truck will have the check engine light/service engine soon light on as the O2 sensor behind the cat is there specifically for that to monitor the cat.
    Last edited: May 29, 2010
    1 person likes this.
  4. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    When you attempt to restart what exactly happens?
    Does the engine turn over?
    Do you get the proper dash lights?

    First you need to determine if this is an electrical problem or a fuel supply problem, checking the fuel pressure and determining that the fuel pump stays continuosly running would be the first steps.

    If the fuel pump doesnt stay running then its either an electrical or possibly computer issue, if the pump stays running but you have a pressure hiccup then it's a pump problem.
    When the filters were changed did anyone pry them open to see if it was clogged?
    You may need to drop the fuel tank to check that the fuel pick-up hasnt gotten loose and isnt blocking the pump from sucking in fuel, if you do need to drop the tank I'd recommend replacing the pump anyways to eliminate the possibility of a bad pump.
  5. Naptime

    Naptime Rockstar 100 Posts

    I've read many accounts or fuel pumps working intermittently prior to failure.
    Also need to check the fuel regulator. Both are common problems.
  6. Scarbreaux

    Scarbreaux New Member

    Thanks Charlie. Your response is truly appreciated. As for as the bad gas goes, I truly don't think that is the case considering this is an on going issue not just a one time thing. Thanks again.
  7. Scarbreaux

    Scarbreaux New Member

    My check engine light does come on from time to time but it does not stay on continuously. And I do not recall it ever coming on during the time that I am having this issue.
  8. Scarbreaux

    Scarbreaux New Member

    I can stop at a stop light, apply gas to take off and it will die as though out of gas. Most often it happens while traveling at a higher rate of speed. I can be going down the I-49 and have it shut off at 75mph. If you try to start it immediately it will not. It sounds as though it is out of gas. However I can wait 15-20 seconds and it will start right up. At times I can go 40 miles before it happens again and sometimes I don't make it 4 miles. Previously changing the fuel filter has been a temporary fix (4-6months). However this time is different, within 2 days it is happening again.

    And yes I do get all of my lights...immediately, even when it wont start the lights will still be on.
  9. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    A guess would be the fuel pump is failing.
    Does it ever miss at idle, RPMs drop then return while at a steady speed, or feel like it has reduced power?
    Normally a blocked fuel filter, especially on an injected engine wont clear it self up, if it's blocked it stays blocked and the problem persists until the filter is changed, ie if it died due to no or low fuel flow it wouldnt restart. Unfortunately for a problem like yours the easiest and usually first fix is to change the fuel filter and oddly enough this sometimes fixes the problem for a while.
    The next step would be to get the pump checked, like I posted earlier first by checking the pressure, then possibly a leak down test of the fuel system.
  10. 2COR517

    2COR517 Epic Member 5+ Years 1000 Posts

    Often times the failure of the fuel pump in these vehicles is caused by the connection at the top of the sending unit. The pins were simply too small for the continuous current draw of the pump. Due to the undersize connection, they heat up. The heating and cooling causes expansion and contraction of the connectors. The expansion and contraction causes movement, ultimately causing the connection to start arcing. The generates even more heat. Needless to say, this is a viscous cycle. As the connections corrode, they cause a voltage drop, which forces the pump to work even harder to try and maintain fuel pressure. If the pump isn't able to maintain pressure, that can cause detonation under load, and overall poor performance. It's very possible that the connection is heating up, opening up, the fuel pump loses power, and the engine dies. Now that there is no current flowing to the pump, the connection cools, and conductivity is restored. Which is why the pump will run and the truck will re-start after a few minutes.

    I learned most of this from a longtime mechanic friend after the pump died in my Tahoe. When I pulled the unit, sure enough one pin was corroded and burnt. I have pics on the other computer, I will post them when I get a chance.

    Ideally you can find a mechanic that will let you "borrow" a fuel pressure gauge. If you can monitor pressure as you are driving, you can check the gauge if the engine dies. I suspect you will see it has dropped drastically, indicating a fuel pump failure.

    Assuming you need a new fuel pump, I would purchase a Delphi from a GM dealer. It should come with a new pigtail. When I bought mine for the Tahoe, the new upgraded electrical pins were "massive" compared to the old ones LOL.

    Good luck.

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