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Starter Question

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by ErikH, Sep 18, 2001.

  1. ErikH

    ErikH 1/2 ton status

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    I have no idea how old my starter or alternator is, and I'm wondering which would lead to starting troubles.

    I replaced the battery just recently, and experienced no starting issues for the week following. But now it seems the K5 has trouble starting (slowly turns as if the battery is weak), especially later in the day. It's not overly warm, so I heat shouldn't be an issue, but maybe a weakened starter is more sensitive.

    Can anybody shed light on the issue before I go out and replace both my alternator and starter?
     
  2. arq

    arq 1/2 ton status

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    GROUNDing, make sure you have ground wires from the battery to the engine block and the battery to the chassis.

    also make sure your terminals are CLEAN and TIGHT. This is another cause of starting problems.

    then there are defective batteries from factory. you can take it back to where you bought it and they should be able to test it.

    lastly your starter may be going bad.

    ARQ.

    1-72 4x4 CST Blazer
    2-71 4x4 CST Blazer
     
  3. 77GMC15

    77GMC15 1/2 ton status

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    First i would check connections and grounding like arq suggested. I would then have the alternater tested because its always been free for me and not too hard to get on and off. A bad one will drain the battery out; so get it tested and if its not bad take the battery in to be tested. Then if its still going on i would get the starter and silenoid tested. If all that still isnt it, check out the battery cables for any burns.

    The road is calling you.......ignore it!
     
  4. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    I'd suggest investing in a voltmeter. Keep it in your Blazer with you. When this happens, first just check your battery voltage. Is it 12.4 volts or higher?
    If battery voltage is at least 12.4 volts then your charging system and battery should be good.

    One test to see if your cranking system is to blame is to test the voltage drop on the ground side. Without disconnecting anything,
    Put the voltmeter (+ lead to the starter mounting bolt), and (the - lead to the - battery post). get someone to crank the engine for a second just to get a reading. There should be no more than .5 volt drop.
    If there is more than .5 drop, there's excessive resistance somewhere in the cranking circuit preventing enough current flow.
    (if it's greater than .5 volt drop, then test the voltage drop on the insulated + side... between the positive battery post and the positive starter post. Again take this reading while someone cranks the engine for a second. this shouldn't be more then a .5 volt drop.)
    Last you can check the voltage drop across the starter selenoid. This reading while someone else is cranking the engine should be at least 9.5 volts.
    This will help you narrow it down to whether its the starter, the + cables, or the - cables.

    Rule of thumb specs for starter voltage drops (while cranking engine)
    Connections .1volt max
    Cables .1 volt/ per foot ' max.
    Selenoid .5 volt max.
    Insulated circuit .5 volt max.
    Ground circuit .5 volts max.
    Starter motor 9 volts min.

    Hope this can help.
     
  5. ErikH

    ErikH 1/2 ton status

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    Thanks for all the help...

    Since the starter is easy enough to remove, I took it out and had it tested... and it failed. I replaced it and now it starts like a champ. Coincidentally, I found that my alternator wiring was bad and it was poorly charging the battery. Fixed that too. So all is good now with the starting system.

    Now I just have to figure out what's wrong with my ignition/carb, and why I have a horrible idle.
     

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