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  1. #1

    Default Fuel ? problem st185

    Wanted to paint the full picture in a new thread and see if anyone had any ideas. Maybe a couple years ago my st185 started experiencing this. The first start of the day it would start but I'd have to let it idle for 30-60 seconds or it would die when give it gas. After that runs and starts fine all day. Even after sitting at work for 9-10 hours. Next day is 50/50 but sitting more than a day it will always do it on the first start. It has gotten worse to now I have to crank the engine for 20 seconds or more and I can hear it barely firing till it is firing enough to idle on its own. Then same thing have to let it idle for 30-60 till I can drive it. To me that seems like a clear fuel problem and not spark or air. I have replaced fuel pump, filter, cold start relay/switch (not sure if those are 1 thing or 2 separate things), the cold start injector was removed and tested ok. And the coolant temp sensor was bad but a new one (green plug) didn't fix it. I can't believe the injectors are bad, for one thing its a JDM low miles engine and two it runs great after the first start. It's a real brain buster. This car has more gremlins then any I have ever owned. Thanks,

    Edit: After posting I remembered I never tried putting a fuel pressure gauge in to see if its low at startup but then with the new pump, filter and no leaks that can't be it. And also the only CEL code is the one for the "no G signal 5 seconds after cranking, check distributor".
    Last edited by 90ToyAllTrac; 08-21-2017 at 07:10 PM.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  2. #2

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    Yep, sounds like cold start or fuel related. You need to check the temp sensor for the ecu (not radiator). You can try a meter/noid light on the injector pig tail to see if a signal is being sent.

    Check fuel pressure regulator. When it goes, the diaphragm usually is first to go and fuel can be leaking though the vacuum house. Apply vacuum to the fpr when the car is running to verify some rpm change.

    As for fuel pressure testing, you'll need a banjo bolt on the too of the fuel filter to attach the guage to. Parts stores often have the bolts in their tool rental kits

    Sent from my XT1053 using Tapatalk

  3. #3

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    My suggestion is that you disconnect the wiring harness to the cold start injector. See if removing that wiring harness changes anything in the symptoms you are now experiencing. If nothing changes at all, then you have a cold start injection problem. The ST185 has a separate coolant sensor for the cold start injector. The one sensor with the green wiring connector is for the ECU. The ECU does not control the cold start injection, a separate sensor does. I'm at work now, and my son has the ST185s in the family, but in a few days, I can tell you where that coolant sensor for cold start injection is located, but I would test first by disconnecting the cold start injector wiring harness to see if it makes no difference. If it is much more difficult to start after an overnight or long time of no starts, then there is something else going on. But I think it is the cold start injection system.

  4. #4

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    I never would have been able to figure this out myself. Here is the official cause.
    Cold start injector. No ground driver from the ECM.
    Assuming that can't be fixed will have to find another ECM.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  5. #5

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    Quote Originally Posted by 90ToyAllTrac View Post
    I never would have been able to figure this out myself. Here is the official cause.
    Cold start injector. No ground driver from the ECM.
    Assuming that can't be fixed will have to find another ECM.
    Before you find another ECM, let me check out the cold start wiring diagram. I do not think the ECM is involved in the operation of the cold start injector (it never was on other fuel injected Toyota engines utilizing an ECM). You have a cold start coolant temperature switch that I am pretty sure provides the ground (when the coolant is cold) to close the circuit to ground, thereby activating the cold start injector. But I would like to verify that to be true on your particular 90 ST185 All-Trac. Give me a day or 2 to verify.

  6. #6

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    Just as I thought. The 1990 Celica All-Trac Electrical Wiring Diagram manual supplement, page 48, clearly shows the cold start injector relay picks up 12VDC power from the starter relay and is grounded only by the cold start injector time switch (which is a combination coolant temperature sensor with an internal heater that open the ground circuit either within a few seconds after the starter relay energizes (i.e.; the starter motor is activated) or the coolant temperature is above a certain temperature level. The ECM is not involved in the cold start circuit.

    I will be working on my son's ST185 All-Trac on Saturday. I will take a pic and let you know where this particular switch is located. Otherwise, I have a diagram I could provide, but with PhotoBucket no longer playing nice with these forums, I'm not sure how to post a pic of this diagram for you.

    Let's see if this works - you may need to expand it to see it better. Also, the Toyota part number for the switch is 89462-20040. If you want some information on how to troubleshoot to make sure this switch is the culprit, let me know.

    Last edited by 93celicaconv; 09-22-2017 at 01:31 AM.

  7. #7

    Default

    Quote Originally Posted by 93celicaconv View Post
    Just as I thought. The 1990 Celica All-Trac Electrical Wiring Diagram manual supplement, page 48, clearly shows the cold start injector relay picks up 12VDC power from the starter relay and is grounded only by the cold start injector time switch (which is a combination coolant temperature sensor with an internal heater that open the ground circuit either within a few seconds after the starter relay energizes (i.e.; the starter motor is activated) or the coolant temperature is above a certain temperature level. The ECM is not involved in the cold start circuit.

    I will be working on my son's ST185 All-Trac on Saturday. I will take a pic and let you know where this particular switch is located. Otherwise, I have a diagram I could provide, but with PhotoBucket no longer playing nice with these forums, I'm not sure how to post a pic of this diagram for you.

    Let's see if this works - you may need to expand it to see it better. Also, the Toyota part number for the switch is 89462-20040. If you want some information on how to troubleshoot to make sure this switch is the culprit, let me know.

    I have had all that stuff replaced. Something else that doesn't make sense is that After its started I have to let it idle for a minute before driving. Otherwise it will die if I give it gas. After a minute it drives fine.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  8. #8

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    Quote Originally Posted by 90ToyAllTrac View Post
    I have had all that stuff replaced. Something else that doesn't make sense is that After its started I have to let it idle for a minute before driving. Otherwise it will die if I give it gas. After a minute it drives fine.
    Maybe you need to check wiring continuity involving the cold start circuit. Still thinking your issue resides with this circuit. Where did you find this Where did you find a cold start injector timer switch for a replacement? If not an original Toyota OEM part, I'm not sure you have a switch that is providing you the same service as OEM. Plus, just because the injector is being energized doesn't mean it is moving to an fuel spray state. Have you ever removed your cold start injector to see if it does spray fuel when energized? Not just making a sound when it energizes, but actually working?

  9. #9

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    Quote Originally Posted by 93celicaconv View Post
    Maybe you need to check wiring continuity involving the cold start circuit. Still thinking your issue resides with this circuit. Where did you find this Where did you find a cold start injector timer switch for a replacement? If not an original Toyota OEM part, I'm not sure you have a switch that is providing you the same service as OEM. Plus, just because the injector is being energized doesn't mean it is moving to an fuel spray state. Have you ever removed your cold start injector to see if it does spray fuel when energized? Not just making a sound when it energizes, but actually working?
    I had a shop remove and test the injector. They also ordered the timer switch sensor. It's a good shop they know what they're doing. I agree the problem has to be with that circuit. I will have to test the wire one of these days.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  10. #10

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    According to the pin diagram JDM ECUs dont have a pin for cold start injector STJ, but USDM does. So where would input/ground or whatever come from on JDM?
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  11. #11
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    Default

    Quote Originally Posted by 90ToyAllTrac View Post
    I have had all that stuff replaced. Something else that doesn't make sense is that After its started I have to let it idle for a minute before driving. Otherwise it will die if I give it gas. After a minute it drives fine.
    Just because something is new doesn't mean it's working, or working correctly. Parts are DOA all the time. If it dies when you give it gas only during the time that the cold start injector should be working then perhaps the injector is overfueling and causing the engine to die. I'd try unplugging it and seeing what happens.

    How did you determine that the ECU is the problem, and that the whole thing needs to be replaced?
    1992 GT-S // 1991 GTFour RC // 2007 Jeep Grand Cherokee CRD

  12. #12
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    I don't think it's the cold start, wouldn't explain it dying under load.



    Check regulator, verify pump staying hot, check distributor, that order.
    I really like the way aaawelder put it: "do not include yourself in this circuit"

  13. #13

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    Quote Originally Posted by MrWOT View Post
    I don't think it's the cold start, wouldn't explain it dying under load.



    Check regulator, verify pump staying hot, check distributor, that order.
    The pump and regulator are brand new and it runs and drives fine all day long after the first start. Right now I'm focusing on how the cold start circuit works since it is not controlled by ECU on JDM.
    Last edited by 90ToyAllTrac; 09-26-2017 at 04:22 PM.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  14. #14

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    Quote Originally Posted by underscore View Post
    Just because something is new doesn't mean it's working, or working correctly. Parts are DOA all the time. If it dies when you give it gas only during the time that the cold start injector should be working then perhaps the injector is overfueling and causing the engine to die. I'd try unplugging it and seeing what happens.

    How did you determine that the ECU is the problem, and that the whole thing needs to be replaced?
    The cold start only sprays when the starter is cranking so it wouldn't be over fueling after started.
    It turns out my JDM ECU doesn't control cold start at all. On USDM it does but JDM it's on it's own loop. My next ? is why does the Ctech BGB show the JDM setup without saying so. Under starting and ignition bottom of page 1. EDIT: I guess that diagram is probably only for the smaller engines but looks right for 3SGTE in this case.
    http://bgbonline.celicatech.com/90ewd/index.html
    Last edited by 90ToyAllTrac; 09-26-2017 at 04:29 PM.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  15. #15
    Senior Member underscore is a jewel in the rough underscore is a jewel in the rough underscore is a jewel in the rough
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    Quote Originally Posted by 90ToyAllTrac View Post
    The cold start only sprays when the starter is cranking so it wouldn't be over fueling after started.
    Where is that information from? It doesn't make sense that it would only work when cranking since there's a time switch. My experience with that circuit on my GTFour is that it stays running for about the length of time you're having problems after a cold startup.
    1992 GT-S // 1991 GTFour RC // 2007 Jeep Grand Cherokee CRD

  16. #16
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    Here's the Alltrac diagram, I'm not sure if it's the exact same as the GTFour system but it should be more correct than the 5SFE/4AFE one posted above: http://www.celicatech.com/bgbonline/90alltrac/FI/FI.htm
    1992 GT-S // 1991 GTFour RC // 2007 Jeep Grand Cherokee CRD

  17. #17

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    I don't disagree that it sounds like the cold start circuit but why would it only do it starting it for the first time for the day? After sitting all day, the engine is going to be cold too and the circuit should engage then as well. Just wondering out loud.
    Mike
    92 All Trac-Daily Driver


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  18. #18

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    Quote Originally Posted by Nitro_Alltrac View Post
    I don't disagree that it sounds like the cold start circuit but why would it only do it starting it for the first time for the day? After sitting all day, the engine is going to be cold too and the circuit should engage then as well. Just wondering out loud.
    I only drive it in the summer time so I'm guessing because it's usually cooler in the morning then the afternoon. I guess I can try a new injector even tho the current one tested ok. It's literally the only thing I haven't replaced.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  19. #19

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    Ok. That might explain something I'd hold off on swapping the injector for the moment. Is it damp or humid the morning so that you drive the car? If so, I'd say there's good possibility that you've got a crack in some wire insulation or a connector & you're getting moisture in there that's interfering with the current/signal.

    Straight up cold start problem should be showing up anytime the engine is cold. It had to be something with conditions first thing in the morning.
    Mike
    92 All Trac-Daily Driver


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  20. #20

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    Dug thru my 91 FSM. The STJ ECM pin is on 2.0 and 2.2 engines - not the 1.6

    Wiring diagram shows the circuit is switched controlled on the ground side. The timer circuit appears to be used to provide a ground connection for initial startup and until the ecm gets enough 'data' to determine what additional fuel is needed. It will then provide ground as needed - probably at some interval like a normal injector.

    Sent from my XT1053 using Tapatalk

  21. #21
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    Before replacing the injector (cheaper to just get it tested & cleaned) I'd try unplugging the injector or the sensor/switch on the tree one morning and see what happens.

    Quote Originally Posted by Nitro_Alltrac View Post
    I don't disagree that it sounds like the cold start circuit but why would it only do it starting it for the first time for the day? After sitting all day, the engine is going to be cold too and the circuit should engage then as well. Just wondering out loud.
    The engine is "cold" in the afternoon but it's still warmer than in the morning, and residual heat in the engine should last a while. From some reading the circuit triggers every time you start up, but the timer gets shorter (or doesn't start at all) the warmer the engine is. It would be easy enough to rig up a light to the timer to see how long it's really running for. It could also be the injector itself, if it's sticking open and dumping fuel even after the circuit is off that would cause problems.
    1992 GT-S // 1991 GTFour RC // 2007 Jeep Grand Cherokee CRD

  22. #22

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    Quote Originally Posted by Nitro_Alltrac View Post
    Ok. That might explain something I'd hold off on swapping the injector for the moment. Is it damp or humid the morning so that you drive the car? If so, I'd say there's good possibility that you've got a crack in some wire insulation or a connector & you're getting moisture in there that's interfering with the current/signal.

    Straight up cold start problem should be showing up anytime the engine is cold. It had to be something with conditions first thing in the morning.
    It did it yesterday at 6pm first start of the day. Perfect warm day. The days when I drive it to work. It would be colder in the morning but it would sit up to 10 hours and still be warmish. And start fine. It's not the conditions.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  23. #23

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    Quote Originally Posted by sefiro View Post
    Dug thru my 91 FSM. The STJ ECM pin is on 2.0 and 2.2 engines - not the 1.6

    Wiring diagram shows the circuit is switched controlled on the ground side. The timer circuit appears to be used to provide a ground connection for initial startup and until the ecm gets enough 'data' to determine what additional fuel is needed. It will then provide ground as needed - probably at some interval like a normal injector.

    Sent from my XT1053 using Tapatalk
    This is the same diagram I used to repin the harness when I did the swap several years ago. Mine, 89661-2B280 ignore the Canada one, has the STA (ground) but no STJ (injector). Does that jive with what you are saying?



    I can do engine work and swap an engine but this stuff is way to technical for me. So I had a shop that I trust try to figure it out. Forgot to tell them it was a swapped setup cause I have chemo brain so they were using wrong info to trouble shoot it and determined a cause thats not possible with my setup. If I bring it back to them I need to give them the correct info to troubleshoot it or they wont do it.

    Thanks guys for the detailed help. I'm starting to think it can finally eventually get fixed.
    69 Mustang coupe 351W edelbrock performer top end, 89 Mustang GT TF top end BBK SSI intake, 90 All Trac JDM 92 swap! "Fiery the angels rose...Deep thunder rolld' around their shores. Indignant, burning with the fires of Orc."


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  24. #24

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    After the cars sits for 10 hours, the engine should be cold. It doesn't make sense that it only does it the very first start of the day but not again after sitting all day and cooling off.

    I'll be curious to see what you find out.
    Mike
    92 All Trac-Daily Driver


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  25. #25

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    Slightly, slightly off topic. Theory on why US ecm has STJ while others do not. Prove the theory though and it might help with the op problem.

    Toyota had to deal with tighter emissions/greater mpg requirements of the US vs non US. it's possible that they put small main injectors in the US vehicles. The larger Japanese injectors could support cold start fuel requirements with a longer pulse width from the ecu. However, the smaller US injector could not be pulsed long enough without risking a burn out. So Toyota solved it by having the ecu take over the cold start injector after its timer expired.

    Or, the US cold start injector timer has a shorter timer length than non US to ensure that excess fuel would not be dumped into the system. The ecu would take over sooner. This implies that the ecu was controlling parts of the fuel system even though it was had not switched closed/open loop.

    In either case, the above would require checking part numbers across the builds. Ideally, the injectors, cold start and o2 circuits would be capped on both builds to verify control activity.

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