Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Desperate help needed for TBI problem!!!!

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by John B, May 11, 2002.

  1. John B

    John B Registered Member

    Joined:
    May 29, 2000
    Posts:
    6
    Likes Received:
    0
    Location:
    Tacoma, WA USA
    To make a long story short my '87 5.7L TBI motor will not start after it has ran for a few miles.

    Here's the details:
    While driving home from work it just suddenly died on the hiway. I towed it home and observed no spark while cranking. I replaced coil, ignition module cap and rotor. Car runs for a few miles then dies again. Towed home again! I replace fuel filter, swap in new computer and swap out fuel pump relay. Same deal! Runs for a few miles (about 15 minutes) then dies and refuses to start! Just keeps cranking

    I check for spark and there is none while cranking. I observe the TBI and no fuel is being dumped. The fuel pump is working (I disconnect the fuel filter and while cranking, it pours!).

    What's the deal?!!!!!!!!!!!!!!!!! I just checked the voltage at the coil and at the injectors and now notice somefuel but the injectors are only getting 9 volts while cranking as is the coil only geting 9 volts. With the ignition in the "on" position, both coil and injectors see 12+ volts. Is the ignition switch on the column hosed somehow?

    HELP!!!!!!!!!!!!!!!!!!!!!!!!
     
  2. mpascino

    mpascino 1/2 ton status

    Joined:
    Jan 1, 2001
    Posts:
    557
    Likes Received:
    0
    Location:
    Connecticut
    Sounds like you have a pickup coil problem in the distributor. After a while the connections inside break. When you changed the ignition mod, you might have moved the wire around enough to make it run again for a little bit. The pick up coil would cause you not to have fuel or spark. They are only like 15 bucks if I remember right. Worth a shot, or try swapping distributors with someone if you can.
    Good luck,
    Mike
     
  3. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    Have you checked the trobule codes? What kind of codes come up. The computer will store trouble codes and not turn on the check engine light.
    For instance: The pick up coil as mentioned above will usually throw a code 42 if bad and may not turn on the "check engine" light
     
  4. John B

    John B Registered Member

    Joined:
    May 29, 2000
    Posts:
    6
    Likes Received:
    0
    Location:
    Tacoma, WA USA
    Well, I replaced the coil pick-up and no change :>(
     
  5. John B

    John B Registered Member

    Joined:
    May 29, 2000
    Posts:
    6
    Likes Received:
    0
    Location:
    Tacoma, WA USA
    Guess I'll get a code reader at Walmart for $20 now and try
     
  6. smack

    smack 1/2 ton status

    Joined:
    Feb 24, 2000
    Posts:
    277
    Likes Received:
    0
    Location:
    Colorado
    I know you said you replaced the module but I had that exact problem and that's exactly what it was. Maybe it's possible that your new module is defective or wasn't installed with the conductive coating??
     
  7. Blazer_Boy

    Blazer_Boy 1/2 ton status

    Joined:
    Dec 16, 2000
    Posts:
    1,669
    Likes Received:
    0
    Location:
    Sioux City, IA, USA
    Nah, save your cash. The ALDL (assembly line diagnostic link) doesn't need a scanner to give you the trouble codes. Look for that plug below the brake release, thats the ALDL. Take a paper clip and jump the two ports in the upper right hand corner. Do this with the igntion off, then turn it on when its jumped. The check engine light will blink out morse code at you. It will also blink the code three times for you. The first code will alway be 12, one blink, pause, two fast blinks. Try that and spend the $20 on something useful.

    It could be something stupid, I think TBI have a brain that kills the fire if you don't have enough oil pressure. That could be out of wack.
     
  8. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    Yeah dont spend the money for a cheapo code reader. Just jumper it out as BB said. If you want to get a scanner get an Auto-X ray scanner. They cost about 150 but they tell you about everything you need to know( voltage, operating paramaters ect) about the various controlls and sensors.

    But for starts just Jumper it out and bring up the codes.
    If you dont have a code chart here's a link:<a target="_blank" href=http://www.batauto.com/GM/86-88_578.htm> TBI Trouble Codes</a>
    Get the trouble code and I'm sure somone here can help.
    Note! if you have disconnected the battery or power to the ECM all the codes will be erased.
     
  9. TopOff

    TopOff 1/2 ton status

    Joined:
    Jan 16, 2002
    Posts:
    1,760
    Likes Received:
    0
    Location:
    Folsom, ca
    If the computer doesn't see ignition being triggered the injectors won't fire.

    Good luck.
     
  10. John B

    John B Registered Member

    Joined:
    May 29, 2000
    Posts:
    6
    Likes Received:
    0
    Location:
    Tacoma, WA USA
    Mystery solved! I re-traced everything I did and noted that the vehicle wouldn't start at all after replacing the coil pick-up. I pulled the distributor again and put the old coil pick-up back in......BINGO!!! It started! I took back the brand new Borg Warner unit that I had just installed and put in another new one.....now it runs like a champ! I just didn't thinnk I would have to pull the disributor and tear it apart 3 times to get it running right! Thanks all for the help!
     

Share This Page