SC300 12v Fuel Mod w/ Pictures - FAQ
07-15-08, 03:55 PM
#61
Pole Position
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This car has over 170k on it now. It has been driven 25+ miles one way to work, so it's around 50 miles a day. Also the car was NA-T at one point. I recently took of the turbo kit to fund another project. This mod has worked and still works great on my car!
09-18-08, 02:56 PM
#62
OK: I have a dilemma, and it's taken my SC out of commission for a while
Some time ago, my fuel pump ecu Shat out while I was driving. the car shut off and would not start up. I towed it home and read an early post on CL about running a jumper wire.
My car is a 1992 SC 300 5spd with a walbro fuel pump (1jz swap on the way)
I ran the jumper wire to bypass the FP ECU, a DIFFERENT mod, which i believe was misinformation posted by someone here a while back and then I started having problems later down the road.
My car wouldnt start from time to time, the idle was rough and low, to the point where if i let off the gas, the car would flat out die, although these could be battery-drain related issues.
Eventually the car got to the point where it would shut off while driving once it was warm, and then it would not restart until some time later, usually hours. My best guess is that the voltage to the pump is constant, and is causing the relay and wiring within the circuit to overheat, which is causing the car to shut off, or the battery voltage is weak and not staying above a level to allow the engine to run properly, or both.
When I shut the car off, I could hear my fuel pump continuing to run, which makes me beleive my fuel pump has been draining my battery the entire time while the car has been off, causing my problems.
Now, if I do this ECU fix, will my fuel pump shut off properly when the car is off, and will my car run like its supposed to, Or should I just say screw it and order a new fuel pump ecu and let that solve my problem?
Some time ago, my fuel pump ecu Shat out while I was driving. the car shut off and would not start up. I towed it home and read an early post on CL about running a jumper wire.
My car is a 1992 SC 300 5spd with a walbro fuel pump (1jz swap on the way)
I ran the jumper wire to bypass the FP ECU, a DIFFERENT mod, which i believe was misinformation posted by someone here a while back and then I started having problems later down the road.
My car wouldnt start from time to time, the idle was rough and low, to the point where if i let off the gas, the car would flat out die, although these could be battery-drain related issues.
Eventually the car got to the point where it would shut off while driving once it was warm, and then it would not restart until some time later, usually hours. My best guess is that the voltage to the pump is constant, and is causing the relay and wiring within the circuit to overheat, which is causing the car to shut off, or the battery voltage is weak and not staying above a level to allow the engine to run properly, or both.
When I shut the car off, I could hear my fuel pump continuing to run, which makes me beleive my fuel pump has been draining my battery the entire time while the car has been off, causing my problems.
Now, if I do this ECU fix, will my fuel pump shut off properly when the car is off, and will my car run like its supposed to, Or should I just say screw it and order a new fuel pump ecu and let that solve my problem?
11-27-08, 10:00 AM
#66
The problem with that is that if you ever did go above, there is a chance you could have a drop in fuel pressure causing the engine to run lean, then it detonates (knocks), causing potential engine damage...
my DD constantly sees redline... and even if it didn't, every once in a while it's a good idea to get the revs up there, get the cylinders nice and hot, clean up some carbon deposits a little...
What is your reasoning for wanting to drop voltage to 9?
11-27-08, 10:04 AM
#67
OK: I have a dilemma, and it's taken my SC out of commission for a while
Some time ago, my fuel pump ecu Shat out while I was driving. the car shut off and would not start up. I towed it home and read an early post on CL about running a jumper wire.
My car is a 1992 SC 300 5spd with a walbro fuel pump (1jz swap on the way)
I ran the jumper wire to bypass the FP ECU, a DIFFERENT mod, which i believe was misinformation posted by someone here a while back and then I started having problems later down the road.
My car wouldnt start from time to time, the idle was rough and low, to the point where if i let off the gas, the car would flat out die, although these could be battery-drain related issues.
Eventually the car got to the point where it would shut off while driving once it was warm, and then it would not restart until some time later, usually hours. My best guess is that the voltage to the pump is constant, and is causing the relay and wiring within the circuit to overheat, which is causing the car to shut off, or the battery voltage is weak and not staying above a level to allow the engine to run properly, or both.
When I shut the car off, I could hear my fuel pump continuing to run, which makes me beleive my fuel pump has been draining my battery the entire time while the car has been off, causing my problems.
Now, if I do this ECU fix, will my fuel pump shut off properly when the car is off, and will my car run like its supposed to, Or should I just say screw it and order a new fuel pump ecu and let that solve my problem?
Some time ago, my fuel pump ecu Shat out while I was driving. the car shut off and would not start up. I towed it home and read an early post on CL about running a jumper wire.
My car is a 1992 SC 300 5spd with a walbro fuel pump (1jz swap on the way)
I ran the jumper wire to bypass the FP ECU, a DIFFERENT mod, which i believe was misinformation posted by someone here a while back and then I started having problems later down the road.
My car wouldnt start from time to time, the idle was rough and low, to the point where if i let off the gas, the car would flat out die, although these could be battery-drain related issues.
Eventually the car got to the point where it would shut off while driving once it was warm, and then it would not restart until some time later, usually hours. My best guess is that the voltage to the pump is constant, and is causing the relay and wiring within the circuit to overheat, which is causing the car to shut off, or the battery voltage is weak and not staying above a level to allow the engine to run properly, or both.
When I shut the car off, I could hear my fuel pump continuing to run, which makes me beleive my fuel pump has been draining my battery the entire time while the car has been off, causing my problems.
Now, if I do this ECU fix, will my fuel pump shut off properly when the car is off, and will my car run like its supposed to, Or should I just say screw it and order a new fuel pump ecu and let that solve my problem?
I ran a "hot wired" fuel pump in my Talon for years with no issues... it turned off when the ignition was switched off, and was constant battery voltage any time the ignition was on, and with a heavier gauge wire as well...
the mod with the Lexus' is similar wiring wise - the relay you wire in to the pump should turn off when the standard pump was supposed to shut off anyways...
11-27-08, 10:51 AM
#68
Anything is possible with enough time and money...
The problem with that is that if you ever did go above, there is a chance you could have a drop in fuel pressure causing the engine to run lean, then it detonates (knocks), causing potential engine damage...
my DD constantly sees redline... and even if it didn't, every once in a while it's a good idea to get the revs up there, get the cylinders nice and hot, clean up some carbon deposits a little...
What is your reasoning for wanting to drop voltage to 9?
The problem with that is that if you ever did go above, there is a chance you could have a drop in fuel pressure causing the engine to run lean, then it detonates (knocks), causing potential engine damage...
my DD constantly sees redline... and even if it didn't, every once in a while it's a good idea to get the revs up there, get the cylinders nice and hot, clean up some carbon deposits a little...
What is your reasoning for wanting to drop voltage to 9?
11-27-08, 11:19 AM
#69
Former Sponsor - Cancelled
How old are your seals? Once they get past a certain age, if you take the injectors out for any reason they're not going back in with out leaking. Just buy some new seals and put them on.
11-27-08, 12:55 PM
#70
The seals are brand new,i stated in earlier post that i changed all the new seals with the H.G change.
I allready took apart the fuel rail(so easy without EGR
)15 mins
so i didnt notice any problems with the injector seal ,but the part where the injector seats in the rail,there was a cut O ring.i guess i cut it when i put it in.It has a chunk missing from one side,probably got pinched.
here i go, back to the toyota dealer
to be raped once again,lol
MITSUGUY- I understand, it IS too dangerous to run lean,man i just dont want to get another used fuel ECU,just to crap out on me again.
I allready took apart the fuel rail(so easy without EGR
)15 minsso i didnt notice any problems with the injector seal ,but the part where the injector seats in the rail,there was a cut O ring.i guess i cut it when i put it in.It has a chunk missing from one side,probably got pinched.
here i go, back to the toyota dealer
to be raped once again,lolMITSUGUY- I understand, it IS too dangerous to run lean,man i just dont want to get another used fuel ECU,just to crap out on me again.
Last edited by LEX_MAN; 11-27-08 at 01:11 PM.
11-27-08, 06:02 PM
#71
The seals are brand new,i stated in earlier post that i changed all the new seals with the H.G change.
I allready took apart the fuel rail(so easy without EGR)15 mins
so i didnt notice any problems with the injector seal ,but the part where the injector seats in the rail,there was a cut O ring.i guess i cut it when i put it in.It has a chunk missing from one side,probably got pinched.
here i go, back to the toyota dealerto be raped once again,lol
MITSUGUY- I understand, it IS too dangerous to run lean,man i just dont want to get another used fuel ECU,just to crap out on me again.
I allready took apart the fuel rail(so easy without EGR
)15 minsso i didnt notice any problems with the injector seal ,but the part where the injector seats in the rail,there was a cut O ring.i guess i cut it when i put it in.It has a chunk missing from one side,probably got pinched.
here i go, back to the toyota dealer
to be raped once again,lolMITSUGUY- I understand, it IS too dangerous to run lean,man i just dont want to get another used fuel ECU,just to crap out on me again.
all fuel systems (that I know of at least), use a flat base fuel pressure across the rev range, and only change pressure due to differences in intake manifold pressure.... our cars are designed to stay at 35-45 psi (off top of my head, its close to that), throughout... the reason the fuel pump ecu is there is to prolong the life of the fuel pump by supplying it 3/4's the standard voltage below 3k rpm because it's already flowing enough volume at standard pressure at those engine speeds...
11-27-08, 08:54 PM
#72
12 volt fuel mod.?
This might be a little off Topic But I have just completed a 2jzgte vvti Swap on my 99 SC300 and was told by one that I did not need to do the 12 VOLT MOD. I was also told by another that I needed to do 12 VOLT MOD. I am looking to buy a AEM wide band as soon as I get some more cash. I took it out for a spin the other day and it seems fine but I don't have a guage to tell me other wise. I also got the part number from the Lexus Dealer ( over the phone) and they said the FUEL ECU part number was the same 92-2000. I am going to take a look at my FUEL ECU to see if it's true. Does anyone know if I need to due the FUEL MOD.? Or what is the best course of action at this point?
Last edited by TURBO819; 05-22-09 at 06:21 PM.
05-20-09, 11:59 PM
#74
because of topics and everyones input such as this one is why i love this forum so much
.. and i know this topic is old but i just read it cuz im really close with my 2jz swap which i showed pic on here about a year ago and everything is coming together and i notice of corse of this fuel cut ive been getting as described in the begining of this thread gj guys.
I just installed a holley fuel pump kit for the supra to put in my sc came with a few peices of new hose clamps connector and a shiny HOlley sticker
where should i place it hmm
. No one has anything to say about holley vs the walbro, or denso? lol
.. and i know this topic is old but i just read it cuz im really close with my 2jz swap which i showed pic on here about a year ago and everything is coming together and i notice of corse of this fuel cut ive been getting as described in the begining of this thread gj guys.I just installed a holley fuel pump kit for the supra to put in my sc came with a few peices of new hose clamps connector and a shiny HOlley sticker
where should i place it hmm
. No one has anything to say about holley vs the walbro, or denso? lol
05-22-09, 11:09 AM
#75
Lexus Test Driver
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Kenne Bell Boost-A-Pump FTMFW. How would you guys setup your fuel pump to run a 9 volts most of the time and have it switch to preset higher voltage only when the engine needs it? I think this is a good way to minimize heating the fuel from constant fuel pump useage.
Last edited by dejacky; 05-22-09 at 11:13 AM.