Ali SC3

iTrader: (10)

wow this is a good find. didn't check into this thread for a while. even the spade connector version you came up with was pretty good and would have likely worked but having the plug is always better. good to know with the male female issue in the future will just check anyways.
let us know how it goes now I am tempted to do that lol.

KahnBB6

iTrader: (5)

Thanks! I thought you'd like the findings The spade connectors would have worked well enough with soldering and a remote set of male/female plugs but factory is so much more preferable.

The new leads are all green or all yellow between the two gauge sizings so I need to label them manually when swapping over to copy the TT ECU wiring diagram. What's strange is that the OEM original wires into the connector are smaller in gauge than the thickest USDM TT wire gauges I ordered. Maybe I have a JDM connector but it all fits and every receptacle is there ready to go.

Where this sub-project stands now:

-- Have two TT Fuel ECUs
-- Have a connector and new wire leads
-- Need to buy the Denso TT pump
-- Need to figure out where to wire EFI2 and get enough length of the right gauge wire for that to go to the fuse box (that part is a bit daunting).
-- Need to figure out which wires from the SC300 connector side correspond to the right leads on the TT ECU connector side.

I probably won't move on this right now because my build still isn't close to being ready to begin. Though I have thought it might be time to begin a build thread and at least start detailing just how insane it is to do a factory style USDM swap.

Ali SC3

iTrader: (10)

oh you should definately do a build thread with all the details. your swap will be more involved than most trying to keep emisisons and mostly factory style. good thing though is enough of us on here know all those little ins and outs to help you achieve that before you pull all your hair out.

I think I have to put back on the 12v fuel mod onto my car to cure some issues with my q45 throttle body going lean. I was going to just relay it off the stock fuel ecu, but now you have me thinking about the gte ecu setup.. lol. I Think I will start with the relay and if it cures the problem I will look into the tt fuel ecu.

what wire is EFI2. I would guess all the wires you need should be on the SC fuel ecu connector already... unless the gte one has an extra function. just a matter of finding both diagrams but running a wire to the fusebox from there is pretty easy, its the same way you run subwoofer power wires down the drivers side and there is a grommet to go into the drivers fender area and then intot he engine bay right by the fusebox (or by the brake boost but then the wire is showing on the inside more).

t2d2

iTrader: (8)

I decided to answer my own question... The only thing I could find through quite a bit of searching was a Supra MKIII thread by someone who couldn't find any answers here on CL, and one semi-answer said unplugging the fuel pump ECU may throw a code 78 CEL but not affect anything. I looked up the CELs and saw no such code, so decided what the hell? As I had hoped, there doesn't appear to be any effect to unplugging it, at least on OBDI.

Ali SC3

iTrader: (10)

yeah I was not sure I want to say I have unplugged it on my 95 and there was no code. 96+ is a different ballgame obd2 has like double the codes that obd1 has but I would guess that it doesn't check for the fuel ecu. its easy enough to leave it plugged in though but some people remove it.

I would still reccomend keeping it in the loop and running a 12v relay triggered by the stock fuel ecu. it only works if your stock fuel ecu is working though.
If you run a standalone you don't have to remove the fuel ecu you can just change the signal to the fuel ecu to run at 12v all the time. its the default in the aem v1 at least.
sure you can probably get a little better voltage to the pump running the power from a relay off the battery, but most prob wont need that, some definitely will.

t2d2

iTrader: (8)

My fuel pump ecu works, but remember, my situation is a bit different in that I bypassed it because it was the best (only) solution for my long-crank start-ups. With the pump ecu jumpered or bypassed, I can turn the key to "On" for a few seconds, build pressure back up, and then it starts quickly instead of cranking forever and killing the starter.

Since I had the back seats out to remove unused stereo wiring (not a smart choice, as it turns out ... that stuff tees off everywhere and is wrapped up well enough to survive re-entry into earth's atmosphere), and discovered the unneeded door lock receiver behind the passenger side panel, I decided to pop the driver's side panel back off and remove the pump ecu. Gotta keep the weight loss balanced side to side!

Ali SC3

iTrader: (10)

i guess it might not do that with the relay, but it should run it at 12v the whole time.
maybe the hose from your pump int he tank to the fitting on the top of the tank sprung a small leak?

t2d2

iTrader: (8)

I suppose there's no reason why adding a relay to the loop would delay the building fuel pressure aspect.

You would say that after I just put the rear seats back in and duct taped the cover over the tank access to better seal the trunk air space. There's probably no way to tell visually, so I guess I ought to put a new hose in there and see if that makes any difference. It wouldn't take much of a leak back into the tank to explain the loss of pressure after half an hour or so of sitting.

Ali SC3

iTrader: (10)

well the non relay way of bypassing it allows it to run with the engine off. if you do the relay off the stock fuel ecu, then it will not come on until you turn the key.

Yeah I mean I have never had that problem it was sort of just an educated guess on what would cause those symptoms.
it should start up right away, its most likely an ecu issue, or a fuel pressure related issue.
could be anywhere in the fuel system really, a bad pump or a bad line, sometimes on these older cars on oem injectors you get a leaky injector that will leak into the cylinder when the car is turned off, which also empties the pressure in the rail, so the next start it has to build pressure again while cranking and also whatever cylinders that have leaky injectors will be flooded and need to be turned over some. I imagine building pressure in the rail will help with half that problem on an a v8 a flooded cylinder or 2 is not much of a problem it will start on 4 cylinders but fuel pressure can be a bit of an issue.

did you have the pump changed recently or do stuff witht he tank? If you did the pump right maybe the injectors are worth a check.
it wouldn't be the first 1uz I have heard of leaky injectors causing hard starts. in fact it happens with all of the older toyota/Denso/Bosch injectors eventually thats why you send them out for a test, cleaning and reflow test.

If I had to guess on any of those above I would say most likely is injectors, you have 8 and they do need cleaning from time to time, any one of them can cause the loss of fuel pressure. the tank hose would be the least likely unless you just did some hard drifting or hit some massive bumps offroad or something like that. sounds like the pump is working so yeah it brings me back to the injectors there was a thread last year in the performance section where that was the fix Ill have to see if I can find it later.

Kahn check out this thread
http://www.supraforums.com/forum/sho...-Fuel-pump-ecu

t2d2

iTrader: (8)

I've tried a different pump, put in new fuel pressure regulator and cleaned / flow tested OEM injectors, checked that the fuel pulsation dampener is working like it should, verified operation of the charcoal canister... About the only thing remaining that makes sense is something in the line allowing pressure to drop. I tried looking into the return line to the tank but it looked to loosen any of the "soft" lines behind the fuel filter, so I didn't want to mess anything up while being unsure which line is which... I like the thought of replacing the supply line in the tank a lot better!

With the 12V mod, at least I have a way to side step the problem for the time being. Can't hurt to look into your relay suggestion, although I'm more for taking "unnecessary" stuff off the car at this point, than adding stuff back in.

KahnBB6

iTrader: (5)

Ali -- I looked up that link ^^ last night. Thank you! I am sure I read somewhere that the EFI2 circuit had to be hooked up as well but it looks like the basic functions are the same.

I am going to look more into it soon with a schematic. Right now I'm tied up with work projects. My latest build progress has been to buy new storage bins for each section of the new engine, ha. When I find my next research materials I will put them in a follow up post here, along with a couple of pictures of the ECU kit as it stands.

t2d2, I'm sorry I can't be of more help with your specific issue.

t2d2

iTrader: (8)

That was in response to Ali's questions.

KahnBB6

iTrader: (5)

Ah, okay then

Ali SC3

iTrader: (10)

Yeah I mean if its working its working, if it was a major leak you would run out of fuel on top so maybe you just have an ecu starting to go bad or really there could be several things as mentioned.

t2d2

iTrader: (8)

I didn't add ECU repair to the list of things already done... Obviously, I'm hoping it's not ECU related, since the only way to bench test that is to run it through every signal/response combo and look for anything out of spec. At any rate, I can't really think of any reason why (or how) the ECU would allow fuel pressure to gradually drop after shutting the engine off. What hand in that process could it play?

If I re-start the car within a few minutes of shutting it off, it roars to life immediately with no need to prime it with the key in the "On" position. I would guess 15-20 minutes is the cut-off, after which it starts returning gradually to "long-crank" mode. So, it has to be a very gradual loss of pressure, whatever's causing it. I'll definitely be trying your suggestion of the feed line in the tank.