dre101

iTrader: (1)

Ok ladies and gents,

I'm having a small problem with my newly purchased 1992 SC400. I've searched everywhere and it seems to be a common problem...with no common solution...

On cooler days or when the motor is cool, it starts right up. No issues there. However, on hot days or after it's been driven and warmed up, say when I put in gas, and try to restart the car, it fires up, idles roughly, and dies out. Toggling the ignition on and off and giving it some gas on the next fire up seems to work. Car then runs fine. No codes, no CEL.

I've heard everything from the fuel ecu, main ecu, plugs and wires, alternator, and even a general tune up working. Does anybody have a *mostly* definitive answer to what the common issue is?

I'd like to be *mostly* positive before I fork over any money

Any and all info is appreciated.

1JZPWRD

iTrader: (59)

Fuel ECU. Try straight wiring it. It wont hurt, but it will elimate this common problem..

dre101

iTrader: (1)

Links on how to straight wire it?

Ninja edit:

Wait, you mean just straight bypassing the fuel ecu entirely?

penusai

iTrader: (2)

from planet soarer:

Faulty Fuel Pump ECU and other causes

The fuel pump ECU can be tested by by-passing it using a bent steel paper clip & bridging the Fp & B+ terminals of the engine diagnostic port. This will make the fuel pump run at full capacity all the time - no safety off when the car stalls or crashes, no half speed when you are cruising - so best to bite the bullet and spend the $270 to replace it if it is faulty. A common failure on the TT and V8.

If you are convinced that the fuel pump ecu needs replacing then:

1. Remove rear passenger side (the "batttery" side) interior trim. A few screws and it lifts out. You may find that removing the back seat is needed. To do that just lift the base up then pull out.
2. Locate and unscrew ECU from chassis, noting the direction and position of mounting.
3. Unplug harness carefully. It can be red hot so check that before just grabbing it.
4. Plug in "new" ECU,
5. Remount in same position as old ECU.
6. Pop trim back on.
7. Pull main EFI fuse in engine bay fuse box to reset ECU, and take for a drive


http://www.planetsoarer.com/IAC/iac.htm

1JZPWRD

iTrader: (59)

Beat me to it.. Thanks for trying help out a new guy!

dre101

iTrader: (1)

Thanks guys!

Quick question though. I've found some info for just hard-wiring the lines at the fuel pump ecu (basically pulling the harness and splicing two of the wires together). Now, if I were to go that route, would I still lose the above benefits? (no safety off when the car stalls or crashes, no half speed when you are cruising ect...)

iridebmx

iTrader: (6)

i personally just jumped the wires. and it has no effect on fuel mileage nor is the furl pressure from leaving your car on without being started an issue

SsSteVen

Has anyone ever left thr jumper in for a looong time? If so, how long? Is your fuel pump still holding up?

DA51

I've had a jumper wire (copper) inside the computer junction box on the motor for 3 years.
After my SC400 died at a light, then I got a push to a side street; I read on our web site of the $400 fuel ECU quitting. The only side effect is that if the ignition is on, so is the fuel pump.
I wonder how long the fuel pump will last now? I've got 160,000 on my 92. 20 years is a long time for any electrical part.

SsSteVen

Yea, I'm wondering how long the fuel pump will last with the jumper in. Anyone?

I just called Lexus of Portand and they want $470.77 for a new Fuel Pump ECU.