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TPI wont start (Updated 9/4)

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Chris Demartini, Aug 21, 2002.

  1. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color="blue">I posted this over at thirdgen, but mabye someone over here can figure out what I screwed up. I just got done putting a 91 TPI setup on my K5, and it will not pulse the injectors. I get power at both sides of the injectors like your suposed to, and i get power from the injectors to the pins on the ECM. All my fuses are good, and I have spark (fires on brake clean). The distributor, coil, plugs, wires, ECM, and custom PROM are all new (chip was done by Jim's Performance in Maryland). I also have continuity between BD6 and BD7 (injector driver grounds) and the negative battery terminal, but how much resistance should there be in that circuit? If I hook a noid light to an injector, it does not flash when I crank the key. Over at thirdgen, they told me to check for a drp (distributor reference pulse) coming from the ignition module in the distributor, so I tried a known good module and it still wouldnt start. How do I check for a drp when cranking? If I turn the distributor cap with the key on, I can hear the fuel pump coming on for its 2 second priming period, does this mean that the computer is detecting the engine turning? I had it hooked up to a scanner this week, it showed no codes and all the sensors were within range. Should the scanner show an RPM reading when the starter is cranking the engine over? Thanks in advance
     
  2. alec78

    alec78 1/2 ton status

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    Re: TPI wont start

    A "DRP" is also sometimes refered to as a Scratch Test, at least that's what GM calles them in a service manual. I don't have one with me to quote (I'll pm you if I fix my problem tonight and have time) Basically, you pop the cap off the distrubitor, remove the rotor, so you can see the modual and wires coming to and going away from it. Then you jump the to and from signal for the pickup coil (not the real name, it alludes me right now, but its the yellow round coil at the base of the dist.) At the same time as you jump the signal, you have a test light on the dist reference terminal going to the ECM. If it lights, so far so good, if not you have a bad module. If I don't pm you tonight, I'll try to tomorrow. Personally I wouldn't follow my directions, I'd wait for the PM. I haven't done this for about 6 years, and my mind is on my own problem. /forums/images/icons/blush.gif
     
  3. HarryH3

    HarryH3 1 ton status Author

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    Re: TPI wont start

    Is your chip setup for VATS (Vehicle Anti-Theft System)? If so, then you have to provide a 2 Hz signal to the VATS input on the ECM. VATS will prevent the injectors from firing if it doesn't get the proper signal. You can just hook up a wire to the pin and start grounding it about twice per second, then hit the starter. If VATS is what's keeping it from starting, it should fire right up. /forums/images/icons/cool.gif

    Note that VATS also "remembers" that someone tried to start the engine without the proper key, and will not allow the injectors to fire for about 2 minutes afterwards. This is to slow down someone with a full set of VATS keys from just trying every one until the engine starts. So let the truck sit for a while, then start the grounding trick, then turn the key. Hopefully you'll be rewarded with a healthy roar. /forums/images/icons/wink.gif
     
  4. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: TPI wont start

    <font color="blue">The chip has the VATS removed, but I'll try that trick (or anything else at this point) the next time I get a chance to work on it, thanks!
     
  5. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: TPI wont start

    <font color="blue">I tried fooling the ECM by grounding the VATS signal wire (blue one) and it still didnt start. Is there any way I can check to see if the injectors could fire? They're from a 5.0 mustang, and I'm not too sure of they're history, except for the car ran when it was taken apart. I've heard of people using Ford injectors on TPI, so they should work, right?

    Also, is there a way I can test for a DRP while cranking? Does the computer receive a positive or negative signal from the ignition module, and can I test for this signal with a test light or DVM? Thanks for the help
     
  6. YtseJam

    YtseJam 1/2 ton status

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    Re: TPI wont start

    You stated you have no injector pulse, but do you also have no spark?
     
  7. Chris Demartini

    Chris Demartini 1/2 ton status

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    Re: TPI wont start

    <font color="blue">I have spark, it'll fire on starting fluid. I also have adequate fuel pressure, the pump is priming like its suposed to.
     
  8. Nonesuch

    Nonesuch 1/2 ton status

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    Re: TPI wont start

    I truly feel for you. I cant really help you out right now because I havent had to mess with my TPI since I put it on (except one bad MAF sensor). I was lucky and my truck fired right off after my install. I hope you figure it out and post up with the problem you had.
    Justin
     
  9. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color="blue">I just got it to start. It turns out, I had the ignition trigger on my Painless fuseblock tied into a source that is off in start. I turned it to start and noticed the CB was on, so I tied into that power source and it started up! The timing is way off, so I need to adjust the timing and let it learn the idle before I can drive it, but it should run by tonight. If your doing this swap, don't be an idiot like me and make sure your ignition power sources acutally stay on in start /forums/images/icons/tongue.gif

    Thanks to everyone who helped
     
  10. BurbinOR

    BurbinOR 3/4 ton status

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    Great news............it's usually the simple fixes that drive you crazy! /forums/images/icons/crazy.gif
     
  11. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color="blue">I have the timing at 6 degrees and its stil a little rough. I had code 42 stored (spark timning) so I disconnected the battery and I'm going to plug it back in and try adjusting the timing more in a little.
     
  12. BurbinOR

    BurbinOR 3/4 ton status

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    By rough, what do you mean? It shouldn't feel rough just with timing...............sounds like maybe a vac leak? TPI plenum and runner leaks are hard to find.........
     
  13. Chris Demartini

    Chris Demartini 1/2 ton status

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    <font color="blue">I got the timing set and its smooth now, but it has a code 54 stored so I gotta see why. I think its because I might have a bad battery.
     
  14. BurbinOR

    BurbinOR 3/4 ton status

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    GM Computer Codes

    Not sure if you have this link already, but code 54 is fuel pump voltage low..............
     

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