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1987 TR No-Start

Discussion in 'Boxers/TR/M' started by xplodee, Oct 6, 2020.

  1. xplodee

    xplodee Formula 3
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    Jan 3, 2017
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    Tim
    Hey All-

    Been chasing some running issues on my TR throughout the summer. Working with an expert but I try to do what I can in-between visits to assist in the trouble shooting. Anyway, we suspect something in the fuel system is in process of failing because we got things running beautifully last time and then the car started having problems stalling immediately after cold and hot starts. We've done a lot so if you have specific questions just ask me and I'll tell you, easier than listing everything. But in short the safety relay functions as do the O2 sensors and throttle switch.

    As of this weekend the car just won't start anymore. It cranks but never fires. At one point it did fire, but stalled promptly after. My tech and I believe it is fuel, the ignition system is checked out and working wonderfully with fresh parts that have been proven for a few k miles. The thing is, with my limited experience, I can't think of anything in the system that would cause both banks to be starved of fuel.

    Could someone way in on this for me? Perhaps send me in the right direction of what to research further?
     
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  3. rpissm

    rpissm Formula 3

    Aug 11, 2013
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    You can confirm its fuel just by taking off the air intake and dripping some gas or spraying carb cleaner down the metering units while cranking. If it starts and runs for a bit, it's conclusively the fuel system.

    Sent from my Moto Z2 Play using Tapatalk
     
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  4. Veedub00

    Veedub00 F1 Rookie
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    do the fuel flow test with the beakers. That will prove your pumps and air metering plate all work together.
     
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  5. Steve Magnusson

    Steve Magnusson F1 World Champ
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    #4 Steve Magnusson, Oct 6, 2020
    Last edited: Oct 6, 2020
    If you've confirmed that the protection relay and the ignition system (on both banks) are working = suspicion has to fall on the tachometric relay operation. Use a jumper wire to connect the positive battery terminal to the violet wire in the x connector:

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    This should cause both fuel pumps to run (even with the key "off" by simulating a closed tachometric relay) -- then try starting. If it runs well (with the jumper in place), then you have to look into the tachometric relay operation (if you need information on that, give a shout back, and I'll dig it up).

    Also, with this jumper in place (and the fuel pumps running), the protection relay should be closed so this gives a good opportunity to (re)confirm that the red wire at the water thermoswitch is +12V and the protection relay is working:
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  6. xplodee

    xplodee Formula 3
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    This is exactly what I was looking for! Thanks as always, Steve. You are without equal.
     
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  8. xplodee

    xplodee Formula 3
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    Well Gentlemen,

    This situation was easier than ever expected. While I ignored spark as the probable cause, when I sat down to start testing I still had to rule it off the list. In fact it WAS spark, the left side coil/module was shot. I replaced with a backup on-hand and the car is running amazingly. This sucker has been dying for a bit and giving me some frustrating problems along with a bad primary coil wire on the right side and poor CIS base tune. The car pulls like a freight train again, finally. Hopefully this sorts out the last of my 2020 problems that I've been dealing with on her.
     
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  9. Steve Magnusson

    Steve Magnusson F1 World Champ
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    #7 Steve Magnusson, Oct 7, 2020
    Last edited: Oct 7, 2020
    The 7-12 coil not working (intentionally) prevents the tachometric relay from working properly so neither fuel pump runs, and the engine won't run on the good 1-6 bank (whereas, the engine will run on the 7-12 bank if the 1-6 coil is not working). Glad that you got it sorted.
     
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  10. xplodee

    xplodee Formula 3
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    that explains so much. So could an intermittent coil on that bank create intermittent variation of fuel pressure during operation? As in weak spark/weak pressure?
     
  11. Steve Magnusson

    Steve Magnusson F1 World Champ
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    Yes, but only if the bad 7-12 coil operation lasted for just a second, or two, and then is OK for a bit again. Any longer than a couple/few seconds of bad 7-12 coil operation and the engine would stall.
     
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