Page 2 of 2 FirstFirst 12
Results 16 to 19 of 19

Thread: Starts and dies immediately; runs briefly if MAP hose disconnected

  1. #16
    Super Moderator dave w's Avatar
    Join Date
    Feb 2011
    Posts
    6,264
    Quote Originally Posted by wanderingturtle View Post

    What is telling the PCM to cut fuel?
    The PCM sends ground pulses to the injectors to trigger the injectors on / off. With ignition key on, in either start or run the injectors will have 12 volts.

    dave w

  2. #17
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    43
    Posts
    70
    Can someone tell me what a normal injector base pulse width is for idle on a similar engine? From my logs it appears that it will idle with the bpw above 2 but dies from the lean condition when it is below 2. I am trying to determine if the lean condition is being commanded by the pcm or if it is due to a mechanical or electrical fault.
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

  3. #18
    Fuel Injected!
    Join Date
    Jul 2013
    Location
    Newzealand
    Posts
    483
    I would try swapping the ignition module from the good runner into it or the whole dizzy .it may have good spark and an rpm trace on the ecu but not enough current to make the ecu trigger the injectors properly.i had a test bench that wouldn't fire the injectors but would show rpm in datalogs fine just my rpm trigger circuit wasn't supplying enough grunt to get the ecu to actually fire the injectors.

  4. #19
    Fuel Injected!
    Join Date
    Jul 2016
    Location
    Weatherford, TX
    Age
    43
    Posts
    70
    I fixed it today, and I'm feeling a bit sheepish.IMG_20171021_203151.jpg
    It was a fuse.
    I have few excuses, except that I never questioned a fuse because I thought it wouldn't start or fire the injectors at all if there was a fuse issue.
    I understand that the PCM connects the ground for the injectors to fire them. What is apparent now is that the start circuit and Acceleration Enrichment circuit are apparently parallel to the main injector circuit. Meaning that it can provide fuel for AE and starting without the main injector circuit being functional.
    1994 Chevy G30 Van "Big Blue"
    5.7 TBI, Vortec Heads, Summit Intake, Thorley Short Headers with dual 2.5" exhaust, 4L80E transmission

Similar Threads

  1. 1990 Corvette Starts then dies
    By Turbo Nasty in forum GM EFI Systems
    Replies: 3
    Last Post: 11-21-2016, 03:35 AM
  2. Starts then stalls ......
    By Nasty-Z in forum GM EFI Systems
    Replies: 4
    Last Post: 04-06-2013, 06:18 PM
  3. Help! 90 Chevy Blazer starts runs dies?
    By ChrisBama in forum GM EFI Systems
    Replies: 3
    Last Post: 03-30-2013, 07:02 AM
  4. truck runs for 30 sec then dies help!!!!!!
    By lilhupper in forum GM EFI Systems
    Replies: 50
    Last Post: 03-25-2013, 02:50 AM
  5. Cant get Tunerpro RT to connect once engine starts
    By Fastmax32168 in forum TunerPro Tuning Talk
    Replies: 34
    Last Post: 10-25-2012, 10:19 PM

Bookmarks

Posting Permissions

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