AAACK! - '97 Burb, 5.7L suddenly "No Start"

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Applegeek, Dec 27, 2008.

  1. Applegeek

    Applegeek New Member

    OK guys, I could use some ideas here.

    My '97 Suburban, 5.7L, auto, K2500 has gone "No Start" on me. It was running 100% perfectly fine, no indication of any trouble, no DTC's, no nothing.

    I parked in my driveway Xmas day. It has been running in this terrible Washington weather, through cold and snow like a champ.

    I go to start it up yesterday morning, and it won't start. I keep trying for a bit, nothing. Motor turns over and acts like its _almost_ going to catch, but it never gets running. Since I could hear the starter beginning to slow down, I put the battery charger on overnight and let 'er charge up 100%.

    This morning, I go out and re-test. The starter cranks the engine quite nicely, it sounds like it normally does on startup. But the engine will not start. I squirted in a shot of starting fluid and re-tried, and I got a backfire, but no start.

    SO: I pulled the injector harness and put on a probe light. Yes, injectors getting power. Yes, fuel pump is running. Yes I checked the spark plug for spark, yes there is spark.

    But all I can get out of this is an occasional backfire....

    NOTE: Occasionally the starter motor will suddenly slow down like it gets stopped in its tracks - almost like the engine is firing at the wrong time. That's why I was suspecting something wrong with the backfire.

    Any ideas where to look?? Is it possibly crank or cam sensor??
     
  2. retired

    retired Rockstar 100 Posts

    Crank sensor most likely
     
  3. ChevyTech

    ChevyTech Rockstar

    I would agree, sounds like the crank sensor sensed it's last crank. I had a situation where the ICM went bad all of a sudden too. I would start with the Crank first though.
     
  4. JMoney02

    JMoney02 Epic Member 5+ Years 500 Posts

    Crank Sensor.......

    Jeff
     
  5. Applegeek

    Applegeek New Member

    OK, local NAPA store actually has one in stock... I'll post results later today.
     
  6. Applegeek

    Applegeek New Member

    Dnag: No go...OK, what is bare minimum for engine run?

    What is the bare minimum for engine "run"...I replaced the crank sensor but "No Go" (I have a backup spare now).

    Battery is charged. Engine cranks fine but will not catch. Every once in a while it wants to fire and the starter motor really struggles for a split- second, then it resumes cranking.

    1. Fuel pressure is 62 to 64psi, by my gauge.

    2. Spark is there. I plug on a spark plug and spark...spark...spark while it cranks.

    3. Test light on injector connector will flash while engine cranks.

    4. New crank sensor installed. No change.

    5. A squirt of starting fluid down the thottle will result in a backfire when the engine is cranked. Without starting fluid it will occasionally fire off a small backfire.

    6. Oil pressure rises up to near normal while cranking.

    7. The spark plugs, wires, rotor etc. are fairly new, about 2-1/2 months old.

    8. No DTC's, no error light, no earlier indication of any type of trouble at all.

    9. I do have a backup spare computer for this truck...I swapped it in, but that made no difference at all.

    Its almost like the spark is just happening at the wrong dammed time, but how is that possible? The distributor hasn't been touched.

    OK, guys...What am I missing here?...Will a bad Cam sensor cause this problem?? It seems like I've never heard of one of those going bad.

    What should I look at next?

    I am all ears here....
     
  7. Applegeek

    Applegeek New Member

    Hmmm...another scan tool also shows no error codes...

    A second scan tool confirms no error codes. According to the computer, everything is hunky-dory. If all I had to do was drive around with the starter motor cranking the engine, everything would be great!
     
  8. DemoMatt3

    DemoMatt3 Member

    regulator? is it flooded, hold it to the floor and crank for a while, see if you get a bit more out of it. Cranking my get faster, trys to start. I've had it happen to mine, once you get it started again it keeps going, and no problems. check to see if your regulator is leaking
     
  9. Applegeek

    Applegeek New Member

    Ahh...maybe this is a clue...

    Pulled the distributor cap off. Checked the distributor for any wobble - it seems tight. The rotor is tight on its shaft, and except for a little gear play it seems OK.

    NOW: I hit the starter to see if the ritir is turning...yep it turns OK...and then BAM! A backfire up the throttle body. Now what's going on there? The distributor cap isn't even on? Is this normal for enough energy to flow through the cap itself to get to a spark plug wire? Or something else??
     
  10. JMoney02

    JMoney02 Epic Member 5+ Years 500 Posts

    No its not normal, the caps NOT On, like you stated. Inside the distributer, is there a module on the base? Check to see if there is, then check to see if the any wires are borke. All the rest of the Dist. posts seem in tolerence....You getting fire from another source? Probably the ICM for the distributer, it gets the IGN TIMING SIG, I believe on this year it still has it? Need a manual for that year do you have one?

    Jeff
     
    Last edited: Dec 30, 2008

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