SC300 12v Fuel Mod w/ Pictures - FAQ
04-25-14, 08:15 PM
#226
Well the GS300 fuel pump ecu is wired up and working, although it is putting the pump always on right now when the key is in the on position, i would have thought it would turn on, prime, then turn off. Need to do some more double checking, either way, progress. the GS300 fuel pump ecu has it's own fuel pump ground wire which i left unhooked for now, i am not sure if it uses that to drop fuel pump voltage or not. fpc and di signals are 0v right now with the ignition in the on position (anyone know what their supposed to be?)
i want to get a proper solution for those with newer ECUs.
i want to get a proper solution for those with newer ECUs.
05-23-14, 12:19 PM
#227
I'd like to give this a try, just in case the fuel pump ECU is the cause of my start-up problems (takes a while cranking, most likely due to the fuel pressure regulator at this point), and I've got the ECU exposed now having just swapped out the driver's seat belt.
But, is there any way to do it in less invasive fashion, since it's kind of a long shot test? Something along the lines of a vampire tap between the green and red/black wires instead of cutting and soldering them. Would that create the uninterrupted circuit between them, or would the continuation of that now-spliced line to the ECU keep it in the loop, so to speak?
But, is there any way to do it in less invasive fashion, since it's kind of a long shot test? Something along the lines of a vampire tap between the green and red/black wires instead of cutting and soldering them. Would that create the uninterrupted circuit between them, or would the continuation of that now-spliced line to the ECU keep it in the loop, so to speak?
06-11-14, 09:18 AM
#228
Driver School Candidate
I actually did this fuel pump ecu mod 2 years ago, saw the write up here on Club Lexus and followed the directions step by step and everything came out good with the car running perfect again. It just took me a while to finally create a profile here and start writing posts.
I was having the same warm start up issues and when it did start the car would have trouble staying running. I was using the hardwire/jumping the pins method through the diagnostic port in the engine bay to keep the car running.
The whole project took about 30mins from start to finish and eliminated any issues i was having and the car started running fine. I did it 2 years ago and havent had a problem related to the mod yet.
I was having the same warm start up issues and when it did start the car would have trouble staying running. I was using the hardwire/jumping the pins method through the diagnostic port in the engine bay to keep the car running.
The whole project took about 30mins from start to finish and eliminated any issues i was having and the car started running fine. I did it 2 years ago and havent had a problem related to the mod yet.
06-11-14, 03:07 PM
#229
Further info:
I just spoke to Curt Aigner at Elmhurst Toyota thinking I had an easy out to locate the connector. Here's the good news: I have a part number!
90980-11362 connector for TT fuel ECU
And the electrical wire/leads that go to it are available (for about $50 or so total)
The bad news is that, as you might have guessed, you cannot buy that connector individually. It is only available on the body harness that goes to the left rear trunk location on Supra MKIV TT's. And that harness has long since been discontinued.
Curt did tell me that the gauge of wiring in either the Supra NA and TT at the fuel pump ECU location are the same. Interesting.
There is a way to do this but it involves finding that connector. Additionally, Curt directed me to Stu Hagen's (of Hybrid GT28 USDM twin turbo fame) website where there are original Toyota wiring schematics that should depict the pinouts for the TT Fuel ECU:
http://97supraturbo.com/Tech.html
For now it seems this will be at an impasse for me until I know more.
All this post relates to is just trying to get this ECU hooked up in the first place let alone tested. And as I mentioned above, apparently Supra MKIV NA owners also have this issue of the TT fuel ECU having a different connector than the NA.
These issues might give some credence as to why this 12V fuel mod has such popularity.
I just spoke to Curt Aigner at Elmhurst Toyota thinking I had an easy out to locate the connector. Here's the good news: I have a part number!
90980-11362 connector for TT fuel ECU
And the electrical wire/leads that go to it are available (for about $50 or so total)
The bad news is that, as you might have guessed, you cannot buy that connector individually. It is only available on the body harness that goes to the left rear trunk location on Supra MKIV TT's. And that harness has long since been discontinued.
Curt did tell me that the gauge of wiring in either the Supra NA and TT at the fuel pump ECU location are the same. Interesting.
There is a way to do this but it involves finding that connector. Additionally, Curt directed me to Stu Hagen's (of Hybrid GT28 USDM twin turbo fame) website where there are original Toyota wiring schematics that should depict the pinouts for the TT Fuel ECU:
http://97supraturbo.com/Tech.html
For now it seems this will be at an impasse for me until I know more.
All this post relates to is just trying to get this ECU hooked up in the first place let alone tested. And as I mentioned above, apparently Supra MKIV NA owners also have this issue of the TT fuel ECU having a different connector than the NA.
These issues might give some credence as to why this 12V fuel mod has such popularity.
I see you followed the path to the end there and it seems the connector is the tough piece, probably is another reason why the 12V mod is so popular.
I will think of a way to get around it, but without the connector or sourcing one of a wrecked car its would be tough. maybe a wtb post on supraforums someone has a donor car sitting around.. def a longshot.
you may be able to get away with those insulated female spade connectors, if you can gets ones of just the right width you can slip them on the factory male pins and they will actually hold pretty well. it will come down to the terminal spacing if that will work or not, it looks a little close in the middle area so maybe not. there is also soldering wires directly to the terminals and then slipping insulation over the wires and terminal to keep them from eachother, I have seen ignitors and stuff wired this way when people don't bother to find the connector.
the pins in the middle are not as high voltage as the 2 power wires and the ground wires, which are the bigger ones I will assume are on the sides that can be connected more easily that way. maybe look into it all I can think of for right now.
you can see an example here, I have even ran my car once with my distributor wires like that, worked just fine even though they are not shielded. I have even tried it on an ecu before that I was missing a body connector and needed a few connections now that I think of it.
Well the GS300 fuel pump ecu is wired up and working, although it is putting the pump always on right now when the key is in the on position, i would have thought it would turn on, prime, then turn off. Need to do some more double checking, either way, progress. the GS300 fuel pump ecu has it's own fuel pump ground wire which i left unhooked for now, i am not sure if it uses that to drop fuel pump voltage or not. fpc and di signals are 0v right now with the ignition in the on position (anyone know what their supposed to be?)
i want to get a proper solution for those with newer ECUs.
i want to get a proper solution for those with newer ECUs.
I'd like to give this a try, just in case the fuel pump ECU is the cause of my start-up problems (takes a while cranking, most likely due to the fuel pressure regulator at this point), and I've got the ECU exposed now having just swapped out the driver's seat belt.
But, is there any way to do it in less invasive fashion, since it's kind of a long shot test? Something along the lines of a vampire tap between the green and red/black wires instead of cutting and soldering them. Would that create the uninterrupted circuit between them, or would the continuation of that now-spliced line to the ECU keep it in the loop, so to speak?
But, is there any way to do it in less invasive fashion, since it's kind of a long shot test? Something along the lines of a vampire tap between the green and red/black wires instead of cutting and soldering them. Would that create the uninterrupted circuit between them, or would the continuation of that now-spliced line to the ECU keep it in the loop, so to speak?
06-11-14, 05:27 PM
#230
It does not just work intermittently, it sort of works or doesn't. your problem sounds like something else. yes there is a short test version, you just unplug the connector, and on the end of the connector use a same thickness gauge wire and cram it into both terminals, instead of cutting and connecting, that should jumper it the same way but really don't leave it like that only as a super quick test.
06-12-14, 01:25 AM
#231
Totally missed this thread for a while, thanks for thie pictures Kahn that really helps.
I see you followed the path to the end there and it seems the connector is the tough piece, probably is another reason why the 12V mod is so popular.
I will think of a way to get around it, but without the connector or sourcing one of a wrecked car its would be tough. maybe a wtb post on supraforums someone has a donor car sitting around.. def a longshot.
you may be able to get away with those insulated female spade connectors, if you can gets ones of just the right width you can slip them on the factory male pins and they will actually hold pretty well. it will come down to the terminal spacing if that will work or not, it looks a little close in the middle area so maybe not. there is also soldering wires directly to the terminals and then slipping insulation over the wires and terminal to keep them from eachother, I have seen ignitors and stuff wired this way when people don't bother to find the connector.
the pins in the middle are not as high voltage as the 2 power wires and the ground wires, which are the bigger ones I will assume are on the sides that can be connected more easily that way. maybe look into it all I can think of for right now.
you can see an example here, I have even ran my car once with my distributor wires like that, worked just fine even though they are not shielded. I have even tried it on an ecu before that I was missing a body connector and needed a few connections now that I think of it.
I see you followed the path to the end there and it seems the connector is the tough piece, probably is another reason why the 12V mod is so popular.
I will think of a way to get around it, but without the connector or sourcing one of a wrecked car its would be tough. maybe a wtb post on supraforums someone has a donor car sitting around.. def a longshot.
you may be able to get away with those insulated female spade connectors, if you can gets ones of just the right width you can slip them on the factory male pins and they will actually hold pretty well. it will come down to the terminal spacing if that will work or not, it looks a little close in the middle area so maybe not. there is also soldering wires directly to the terminals and then slipping insulation over the wires and terminal to keep them from eachother, I have seen ignitors and stuff wired this way when people don't bother to find the connector.
the pins in the middle are not as high voltage as the 2 power wires and the ground wires, which are the bigger ones I will assume are on the sides that can be connected more easily that way. maybe look into it all I can think of for right now.
you can see an example here, I have even ran my car once with my distributor wires like that, worked just fine even though they are not shielded. I have even tried it on an ecu before that I was missing a body connector and needed a few connections now that I think of it.
I've taken a break on solving the connector issue but I haven't given up yet. I did try getting a 1998 sub-harness from a part out car on SF but the seller informed me that wiring would not be sold separately. Alternatively I am thinking of shooting Tweak'd an email since they must have found a way to acquire or remanufacture all those connectors for their custom GTE harnesses.
I could also try your soldering suggestion, yes. I'm not sure whether to leave my NA fuel ecu alone, 12V Mod it or actually try getting the GTE fuel ecu hooked up at this point. As you mentioned above, the fuel issue either seems to be something some cars have or don't at all.
If the part number exists and supply is still out there then there must be some way to have it ordered through someone. Toyota lists it in a big catalog of connector types after all.
06-18-14, 04:28 PM
#232
Pole Position
I had something strange occur after I completed the mod. I only gave it a direct 12 volts because my fuel pump ecu burned out. I figured it was cheaper to just bypass it. However, now I can occasionally hear my pump continuing to run after I turn the car off and pull the key out, and they only way to stop it is to disconnect the battery. Weird? Just curious if anyone else has experienced this, I'll probably just wire a manual switch on the dash and be done with it.
06-19-14, 07:53 AM
#233
it should turn off after a bit when the main relay turns off like 5 or 6 seconds after shutting it off.
on some cars it doesn't but I don't really know why... maybe something is wrong with one of your relays or someone else has done some other wiring.
Kahn if you can get a connector that is Ideal. might be worth looking around and I would probably check with tweak it would be worth it to do it the right way since you have the ecu already. unless the stock one is working fine then maybe I would let it be for a while. my stock one works just fine with the walboro never had any issues and no 12v mod.
on some cars it doesn't but I don't really know why... maybe something is wrong with one of your relays or someone else has done some other wiring.
Kahn if you can get a connector that is Ideal. might be worth looking around and I would probably check with tweak it would be worth it to do it the right way since you have the ecu already. unless the stock one is working fine then maybe I would let it be for a while. my stock one works just fine with the walboro never had any issues and no 12v mod.
06-20-14, 03:06 PM
#234
Update on my 90980-11362 connector search. I tried Tweak'd Performance, Sewell Lexus and Carson Toyota and none of them can source the part let alone find it in their systems. It really was intended as part of a body sub harness that connects to everything from the fuel ECU to the taillights.
Best bet for this is to luck out and find a dismantler parting out a wrecked 93-97 Supra and request that sub harness in total or to directly solder leads onto the TT Fuel ECU prongs (with heat shrink rubber) and solder those prongs and the connectors on your TT harness to some generic connectors for future replacement.
Per this thread on SF, these are the connector leads that can be ordered IF you had the above TT fuel ecu connector:
http://www.supraforums.com/forum/sho...-Qoute-please&
82998-12380 TERMINAL, (order 4x)
82998-12340 TERMINAL (order 4x)
I'm not sure what my plan will be at this point. I may pursue the 12V fuel mod after all so long as I know I won't burn out the NA ECU and so long as factory shutoff can be preserved.
UPDATE & CORRECTION:
It turns out the plug actually is available. It's been referred to incorrectly as the "male" connector where in fact it is a "female" connector according to Toyota. Ignore how it looks and pay attention to the pin orientation.
The actual "male" connector is literally the part of the TT Fuel ECU itself that has pins sticking out of it-- so naturally you can't order that. It's part of the TT Fuel ECU assembly and isn't replaceable.
The connector "90980-11362 housing" is a Japan special order part but can be sourced from a Toyota dealer. $10.
Best bet for this is to luck out and find a dismantler parting out a wrecked 93-97 Supra and request that sub harness in total or to directly solder leads onto the TT Fuel ECU prongs (with heat shrink rubber) and solder those prongs and the connectors on your TT harness to some generic connectors for future replacement.
Per this thread on SF, these are the connector leads that can be ordered IF you had the above TT fuel ecu connector:
http://www.supraforums.com/forum/sho...-Qoute-please&
82998-12380 TERMINAL, (order 4x)
82998-12340 TERMINAL (order 4x)
I'm not sure what my plan will be at this point. I may pursue the 12V fuel mod after all so long as I know I won't burn out the NA ECU and so long as factory shutoff can be preserved.
UPDATE & CORRECTION:
It turns out the plug actually is available. It's been referred to incorrectly as the "male" connector where in fact it is a "female" connector according to Toyota. Ignore how it looks and pay attention to the pin orientation.
The actual "male" connector is literally the part of the TT Fuel ECU itself that has pins sticking out of it-- so naturally you can't order that. It's part of the TT Fuel ECU assembly and isn't replaceable.
The connector "90980-11362 housing" is a Japan special order part but can be sourced from a Toyota dealer. $10.
Last edited by KahnBB6; 12-17-14 at 12:29 AM.
06-23-14, 09:07 AM
#235
thats not any fun. I wouldn't do the 12v fuel mod still unless you need it. you can always drop in a less demanding walboro and use the n/a one. or try the GTE pump with n/a ecu and see what happens.
last ditch effort I would use those female spade connectors to slide tightly over the male pins on the fuel ecu, then hit it with some solder so they never move or come apart, and then slide insulation over it and repeat.
last ditch effort I would use those female spade connectors to slide tightly over the male pins on the fuel ecu, then hit it with some solder so they never move or come apart, and then slide insulation over it and repeat.
07-06-14, 07:40 AM
#237
Driver School Candidate
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1992 SC 400 quit running with no restart while driving 45 mph on the road.
I installed a duracell gel pack battery less than 1 yr ago.
The car had its throttle body removed and cleaned 2 months ago, valve cover gaskets replaced.
128,000 miles on trouble free car. Fuel Control Unit replaced 8 years ago. I have owned this car for 16 years.
My cranking power seemed to be weakening or possibly the engine harder to start the past 3 weeks. Seemed quite hard to start the morning of the day it quit. I did stop 3 times after the intial hard start and it started easier after first start of the day. I was able to coast into a parking lot. The starter seemed like it was even harder to start. I checked out my battery with my home charger and it showed well into the green. I recharged it for a brief period as it showed complete charge. Initially I thought the duracell was shorted. I removed the battery and attached jumper cables to the battery connectors to a running Sequoia. It acted as if I had a dead battery and would not accept any only brief starter relay clicking. I returned with a 850 amp battery and the posts were on opposite sides but hooked up the heavy jumper cables and the strong battery acted dead through the jumpers hooked up to the battery connectors.
I have a friend that offered to use his OBD2 reader but my car is too old for this unit to hook up to. I very much would like some help as the car is away in a parking lot that will have to be towed otherwise and time is of essence.
I installed a duracell gel pack battery less than 1 yr ago.
The car had its throttle body removed and cleaned 2 months ago, valve cover gaskets replaced.
128,000 miles on trouble free car. Fuel Control Unit replaced 8 years ago. I have owned this car for 16 years.
My cranking power seemed to be weakening or possibly the engine harder to start the past 3 weeks. Seemed quite hard to start the morning of the day it quit. I did stop 3 times after the intial hard start and it started easier after first start of the day. I was able to coast into a parking lot. The starter seemed like it was even harder to start. I checked out my battery with my home charger and it showed well into the green. I recharged it for a brief period as it showed complete charge. Initially I thought the duracell was shorted. I removed the battery and attached jumper cables to the battery connectors to a running Sequoia. It acted as if I had a dead battery and would not accept any only brief starter relay clicking. I returned with a 850 amp battery and the posts were on opposite sides but hooked up the heavy jumper cables and the strong battery acted dead through the jumpers hooked up to the battery connectors.
I have a friend that offered to use his OBD2 reader but my car is too old for this unit to hook up to. I very much would like some help as the car is away in a parking lot that will have to be towed otherwise and time is of essence.
08-16-14, 02:12 PM
#238
So my question , the only reason to do the bypass to a good running stock SC300 or 400 if the ECU goes bad, is the high cost of a new ECU on an old car. If you do the bypass is it best to plug the old ECU plug back into the ECU or leave it unplugged?
Last edited by bigwhite; 08-16-14 at 02:40 PM.
08-18-14, 05:23 PM
#239
yes, you can source a replacement but the cost is very high for new if available. you can find a good used one and hope it lasts longer, I am still on the original one no issues for me yet, but some people just like to bypass instead. it does not matter if you plug it back in or not as far as I remember but you can just plug it back in so it isn't moving around all over the place.