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Thread: 20V BT help

  1. #1
    Join Date
    Aug 2006
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    20V BT help

    Hey Everyone,

    I'm not sure whats going on with my 20VBT. It suddenly decided to do this yesterday. Everything was running fine on Friday when I last drove it.

    Issue: When I try to start the car, the engine cranks and RPM reach 1000, but after a sec, the car isn't able to hold idle and stalls out.

    I don't really know where to begin to look for the problem, but I suspect a vacuum leak maybe? Here is a video of the problem https://www.youtube.com/watch?v=f39f...ZVS_Pt-EseCKXQ

    Thanks in advance.
    Joe

  2. #2
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    Jan 2013
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    Bellingham, WA
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    do you have a fuel pressure gauge? will it rev up with the gas pedal?

  3. #3
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    Quote Originally Posted by ThrashLoaf View Post
    do you have a fuel pressure gauge? will it rev up with the gas pedal?
    No fuel pressure gauge, it does rev up, but it stalls out the same way.

  4. #4
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    check your codes... oh wait no engine light :|

  5. #5
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    To me that sounds like a vacuum leak. I googled really quickly - http://www.my-acoustic.com/Car/engin...ing_IDLING.htm

    Ray
    AE86 | Tacoma X-Runner
    4AGE 20V | 1GR-FE


  6. #6
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  7. #7
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    I'll look into the fuel as well. Thanks

  8. #8
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    What was your find? Just curious since I'm running a 20V as well.
    AE86 | Tacoma X-Runner
    4AGE 20V | 1GR-FE


  9. #9
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    Update ... I didn't do anything big. But the car started up with no problems this weekend.

    My exact steps. Rolled the car backwards (in process rocked it as well), because I had to access a broken tree branch above the car....

    My thoughts is that there is either gunk at the bottom of the tank that clogged the fuel pump in the tank or I have a stick fuel pump as noted in this thread http://www.dorikaze.net/showthread.p...674#post259674 see post #8

    I put in a bit of fuel stabilizer and some fresh fuel into the tank in hopes that it all works out on it own ....

  10. #10
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    Jan 2013
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    you can also check the fuel pump power wire and make sure it actually has 12v when cranking AND. on the run position. my coupe had an issue where it had power when crank but not when on run

  11. #11
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    does the BT have an oil pressure switch triggered fuel pump relay? Just a long shot, but I've dealt with bitchy oil pressure switches before and had similar results.
    If there's one thing I've learned from the first two thirds of the MC Hammer Biography, it's that money never runs out.

  12. #12
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    Quote Originally Posted by ThrashLoaf View Post
    you can also check the fuel pump power wire and make sure it actually has 12v when cranking AND. on the run position. my coupe had an issue where it had power when crank but not when on run
    That's just checking the connectors with a volt meter in the trunk area, right?

    Quote Originally Posted by Chewy View Post
    does the BT have an oil pressure switch triggered fuel pump relay? Just a long shot, but I've dealt with bitchy oil pressure switches before and had similar results.
    To my knowledge no

  13. #13
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    yeah pull the two prong plug off, technically it's like 4 wires two per prong. ones ground and ones power so unplug it, turn the key to run, put your black probe on a good ground source like something with bare metal, then put your red probe on the prongs and see if one has power. (the body side of the wiring of course not the pigtail coming off the. pump.)

    if neither have power, have someone turn te engine over while you check both prongs again and see which one has power.



    if you only have power during crank that will cause it to start and then immediately run out of fuel everytime. also I'm pretty that's an issue with the fuel pump relay but don't quote me I'm kinda throwing that out of my ass

  14. #14
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    UPDATE* Jan. 28, 2016

    So over the past year Ive done some maintenance with nothing to show.

    I swapped my gas tank, fuel pump and fuel filter with all new OEM replacements. Ive installed a FPR with a guage and I am reading ~3-4 kg/cm2 (50psi) at start up. But once I let it run, the pressure gradually dies off and the car shuts off.

    Also I popped open the fuel box in the engine bay and checked the EFI MAIN relay, it appeared to be in good condition, but is there a way I can check that?


    Suggestions?

  15. #15
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    This is an AE86 GTS that you'e swapped a 20V into? the AFM was keeping the fuel pump on while the engine was running, the pump also primes while cranking. you need something to keep your circuit opening relay energized while the engine is running, usually there's a line on the PCM, but the polarity might be wrong.

    Use the check connector to force the fuel pump on and see if it runs fine like that.

  16. #16
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    Quote Originally Posted by Sparkie View Post
    This is an AE86 GTS that you'e swapped a 20V into? the AFM was keeping the fuel pump on while the engine was running, the pump also primes while cranking. you need something to keep your circuit opening relay energized while the engine is running, usually there's a line on the PCM, but the polarity might be wrong.

    Use the check connector to force the fuel pump on and see if it runs fine like that.
    Yup this is a GTS. Im not 100% sure what you mean by PCM (pulse control module?) Sorry for the questions, could you link something with a picture, I can't visualize the connectors you are referring to.

  17. #17
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    PCM is powertrain control module, modern slang for ECU or brain box.

    Diagnostic connector under the hood:


    Jump FP to +B and the fuel pump will run whenever the key is in the run position. If this works then your circuit opening relay is not staying on, which makes sense because you removed the AFM. Here's the relevant portion of the circuit diagram. I dont haVe pictures of the COR or afm connector.

  18. #18
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    Thanks for the awesome info. I will test this and update.

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