Results 1 to 6 of 6

Thread: Slow crank and low voltage

  1. #1
    Join Date
    Apr 2017
    Location
    Marylad
    Posts
    1

    Cool Slow crank and low voltage

    I have a1994 6.5 diesel blazer new batries(I had the batteries load tested and they read excellent) new alternator I have been noticing my voltage guage reads 9.5 before I start the truck and the starter cranks like it. Immediately after starting the guage goes to 14.5 for a bit and it levels off right at 14 as expected after about 30 seconds. This happens weather the truck has been sitting for 1 min 1 hour or 1 month. I am thinking possible ground issue or possible bad connection at positive starter connection. I'm hoping this a common problem for the volt guage to read low before start and see slow cranking only for the voltage to go back up with the alternator charging. Please save me some time with your knowledge diesel page users.

  2. #2
    Join Date
    Feb 2014
    Location
    NC
    Posts
    32

    Default

    The low voltage is the glow plugs warming up. When you turn the key wait for the voltage to go up then turn key to start.
    Last edited by snarl; 04-29-2017 at 19:11. Reason: spelling

  3. #3
    Join Date
    Feb 2003
    Location
    Grand Rapids MN 55744
    Posts
    1,648

    Default

    Howdy
    Welcome to TDP!
    Probably the most common issue with the charging/starting on this vintage of truck is CABLES and CONNECTIONS. If you do a search on this forum you will find tons of information about this subject.
    The biggest problems are poor cable condition, meaning interior corrosion that cant be seen and the factory end connectors and ground connections.

    Do a search and pick the remedy that best suits you. It seems that everyone has a slightly different way to fix this problem and most of the ones posted are effective.
    1996 Chvy 3500 CCDWLB 6.5 Heathed, NO vac, marine injctrs, ARB bumper, BIG pipe, 3" lift, bright lights, bypass oil system.
    1986 Chvy 6.2 M1009 blazer RAM AIR, Headers, Custom interior
    2001 Chinook RV, V10 gas
    1974 John Deere 1530 diesel tractor
    1993 John Deere 455 Diesel lawn mower
    1967 GTO, 1989 Honda Transalp
    2009 VW Jetta TDI, flashed and piped, 6speed, fun car!
    1998 6.5 suburban, stock, daughter's
    1993 6.5 3500 CCSWLB GM8, Heathed, big exhaust, gauges, Son's

    1984 6.2 ATS turbo 3500, SCDWLB - Son's
    3 kids, 1 wife, 1 dog
    Gunsmith, Tactics Instructor, Fabricator USMC 87-93 Semper Fi!

  4. #4
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,283

    Default

    What Snarl said ....

    If the truck has the factory type side terminal cables they are notorious for issues after a few years.

    Even the crimped ends of the ground cables where they bolt to the block can go sour.

    The positive crossover cable that ties the two batteries together is another trouble spot.

    The 94 has a long cable on the RH side the connects to the positive terminal and then runs back to the firewall junction block.

    This cable provides all the chassis power.

    A combination of poor connections within the crimps of all the various battery cables is likely the issue with the slow cranking.

    New "OEM" cables are no better than parts house replacements.

    The best fix is to remove the side terminal ends and solder on copper eyes.

    Corrosion starts deep in the cables and the crimps are usually not soldered.

    I have fought this fight before and ended up replacing the cables with fine strand welding cable and soldering on all the eyes.

    The small run the feeds the chassis junction block also needs to have an eye soldered on the battery end.

    The grounds are every bit as important, both at the battery and the engine block ends.

    Make sure to connect the grounds that go from the battery neg terminal to the sheet metal as well.

    Once these items have been addressed things should be fine.
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  5. #5
    Join Date
    Dec 2009
    Location
    In the North
    Posts
    700

    Default

    seems perfectly normal to me,. 9+ Volts when the glow cycle is on is about right,.
    If it's starting ok, i say drive on!
    1999 chev suburban C2500
    300,000 mi

  6. #6
    Join Date
    May 2014
    Location
    us, ga
    Posts
    166

    Default

    Make sure the grounds are clean at the passenger rear stud, and the ground strap on one of the starter bolts to the frame. I actually run an additional ground from a starter bolt back to the battery.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •