Buying 1990 GMC suburban..need help!

Discussion in 'General Chevy & GM Tech Questions' started by warwagon, Aug 7, 2008.

  1. warwagon

    warwagon New Member

    I'm finally getting close to buying the Suburban I wanted for some time now. The old "tank style box" 1990.

    The current owner says the main problem with it right now is , when its cold(sitting all night ) it starts and runs fine . when its hot, it starts and runs fine.

    However, if its anywhere inbetween, as cooling off from hot, or not completely warmed up, it wont start and a fuel smell is coming from the motor as if its flooding etc.

    What could possibly be causing this to happen? What can i test to see what it my be?

    I'm looking forward to getting this beast!!!!!

    Thanks for any help you can give.

  2. ct9a

    ct9a Epic Member 5+ Years 1000 Posts

    Bad injector(s) maybe? Vacuum leak somewhere?
  3. warwagon

    warwagon New Member

    80% of time runs great

    The owner says it runs fine 80% of the time. Its just that brief window that it wont start and smells of fuel, like it flooding. Other then that, runs great.

    Is there any sensors that would tell the fuel system to pump fuel in or???
  4. collinsperformance

    collinsperformance Epic Member 5+ Years 500 Posts

    run a scanner or jump the term and see if there are any codes then look at those issues.....mike
  5. warwagon

    warwagon New Member


    I know on my Dodge diesel, I can get the codes by turning the ignition 3x off and on and they are on the odometer...How do I get the codes off of the GMC???

    Thanks. Ed
  6. ct9a

    ct9a Epic Member 5+ Years 1000 Posts

    The ALDL (looks like a multi pinned female plug) sticking out the bottom of the dash on the driver's side. Get a paper clip and jump the A terminal to B terminal (top row all the way to the right and top row right next to it) and turn the ignition on. The SES light will start blinking at you, read the codes and look them up.
  7. voodoo 350

    voodoo 350 New Member

    a bad t.p.s sensor can cause that to happen. they are spring actuated and if the unit is bad heat can effect it. my father in law had the same truck with the same problem and thats what it was but as suggested read the codes first. the ses light will flash out the codes to you if you jump the terminals desceribed above. althought the code does not always pinpoint the cause.
  8. warwagon

    warwagon New Member

    Found the problem

    The seller was baffled by the problem and it happened to him when it was cold the day before I came over...

    It would not start cold and he checked the spark and found none...He changed the ignition back to stock and the problem went away.

    Apparently the aftermarket "MSD" ignition(coil) system was intermittently not putting out spark.

    I have not had any problems at all. She runs like a top even with 230k on the clock.

    Thanks everyone for your help. Now I just have to find a good source of parts for it, dress up stuff, dash mats etc.
  9. Mike's '90 suburban

    Mike's '90 suburban New Member

    I buy items from L.M.C. truck parts. Their on the web. This company carries a wide variety of what you're looking for.

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