1988 c1500 ignition issue

Discussion in 'Chevy C/K Truck Forum' started by mig8830, Sep 1, 2013.

  1. mig8830

    mig8830 New Member

    Hello everyone this is my first thread on this forum.
    Ive been searching and searching and searching some more...
    But ive not been able to find an answer.
    Ive had an issue with not spark or fuel to my 4.3l tbi. At first i was the fuel pump, i replaced it and it ran
    A couple of days and then it died again, i wasnt getting a sinal from the distributor to he ecu so i replaced the distributor (all new module, cap, and rotor) it ran fine again for a couple of days. Then it died again. So ive checked all my grounds and all my hot wires and everything checked out. Still nothing, so i got frustrated and left it for a coulle of weeks. Then friday i decided let me see if i could get my truck started. Sure it enough. Fired right up. Drove it up and down the driveway to see how it would do umder load and it was fine. I backed into the road to drive it around and it diead again.
    So ive been looking at it with my dad today...

    We discovered that the plug with the 2 wires that go from the ign coil to the ign module when we had a tester light from the positive to the hot wire it would start, like nothing ever happened. Take the tester light off and it died again. Same deal when we put ground to the other wire. We had the modue and coil checked and they both tested good.
    My question is what could this possiy be? Its lnly between there that the problem seems to lie, and its just 2 sime wires there. Would i do any harm to anything splicing a wire from the battery to the hot wire and leaving it there? Or does anyone have any idea what exactly could be causing this?

    Sory for thelong story i was just trying to be as detailed as possible seeing that ive not found a single person online who has had this kind of problem.
    By the way all my sensors were replaced, i rebuilt the tbi unit and got new injectors on it. Ive replaced the ecu 3 times hinking it may have been that. Any input would be GREATLY appreciated.
    Thanks in advance,
    Miguel
     
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    I dont believe Ive ever heard a problem quite like this.
    Given your findings and test results I suspect you have a bad ground at the distributer or the ecu, I dont remember the module having a ground.
     
  3. mig8830

    mig8830 New Member

    thanks for the quick reply

    i thought that as well but all the grounds to the ecu are good, i even added a ground from the body of the ecu to the body of the truck and its still the same deal. The module is grounded directly to the distributor through the metal plate on the bottom of it. I guess i can try grounding the distributor to see if that will help?

    I mainly want to know if it will harm anything by splicing in a wire from the battery to the wire between the distributor and coil?
     
  4. 261618_Noname_1879.jpg
    Did you check the fuel pump relay and oil pressure sender switch? I recently had a problem with fuel delivery and the relay and oil pressure switch were both bad.

    Something else: Does your truck have a tachometer? Try disconnecting the tach lead, as it shorting could create an internittent spark problem.

    One more idea: Go to this site and follow the instructions to check the codes on your truck. http://www.troublecodes.net/gm/

    Hope it helps....
     
  5. mig8830

    mig8830 New Member

    Thanks for reply. The fuel pump relay is good, the fuel pump is priming and pumping fuel to the tb.
    Ill check the oil pressure switch. If the oil pressure switch was bad would the engine start at all? Because i can get the engine started if i put 12v to the wire between the coil and dizzy.
    I dont have a tach and i made sure that the wire was seperater from the other one.

    You think it could possibly at all be the wires themselves that are bad? I checked and the replacement wires cost $155 at gm! The painless one costs $30 though. But it makes me think maybe there is something special or specific about those 2 wires?
     
  6. Grady

    Grady Member

    In the old days, a wire from the + terminal on the battery to the distributor side of the coil was called a "hot wire". It bypasses everything by putting power to the ignition. It's like putting the key in and turning it to "on". Something on yours is exercising it's right to veto. I'd start with the easiest and cheapest. Pull the connector off the temp. sensor and see if it makes any diff. I've had problems with mine - they're cheap and easy to change. I would use alligator clips or some kind of connector for any "hot wire" - you don't want to leave that circuit energized if you aren't driving - if nothing else it will probably drain the battery. I don't know what sort of problems you could be creating by hot wiring it as I haven't had any reason to do that since they started using ECUs. Someone smarter than me may be able to tell you if you might back feed something you shouldn't by doing that. You should try to find what the real problem is as there are only so many possibilities and you have done quite a few already.
     

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