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The ECU is only supposed to help the Fuel Pump. So, I would check the fuel pressure on the fuel pump first. Then I would replace the fuel filter (right in front of left rear tire on the underside of vehicle.) If all is well there I would check the fuel pressure regulator--it may be wide open--allowing the /ECU to run all the time. If you are going to replace the fuel filter-E-Mail me first! I had one bad time replacing mine! Now , I know the tips I got from Lexus mechanics I will pass to you! Good Luck! By the way, The ECU's don't like water or moisture. My left driver's window leaked and caused mine to go out. I thought it was my fuel pump! Replaced the fuel pump 2 times! $295.00 each! I replaced with new because it is in the gas tank! By-the-way--there is access hole behind rear seat to get to fuel pump--you do not have to remove fuel tank from trunk!! My '92 has 180K and was working great until the water got in there.

First of all, remove both parts of back seat. Then, remove the trim panel cover under the rear window behind the driver's seat. Take your time and remove bolts or push -in-tabs carefully so you don't break anything! You want to be able to re-use them. If you do break them, any local O'Reillys or Autozone will have some. Now-VERY IMPORTANT- disconnect the NEGATIVE battery cable. Then, let's insure that the Fuel Pump Controller(Module or ECU) is your problem. Take a 10 M wrench or socket and ratchet and remove the bolt holding the ECU bracket to the body of the car just under the window. Then disconnect the wire harness(take your time and push in on the little !/4" square tab and wiggle it apart) Now look at the wires--there is 1 wire that is green and 1 wire that is combination red/black.(These wires should be on one end and be larger diameter than the other wires. Now, take a piece of insulated wire the sane guage as those 2 wires and jump from the green wire to the combination red/black wire. Now, reconnect the Negative battery cable. Now, if possible, have a friend keep an eye on the jumper wire while you try to start the car. If it starts up and there is no arcing where you jumped the wire, you done good.. Now, turn off the key, take a 6"-8" piece of electrical tape and tape the jumper wire so it won't come out. Now, drive the car for a few days and see if that fixes the problem. If so, get on E-Bay and find a good used one that is out of a '98,'99' or 2000 Lexus SC 300.(A new one is about $385.00. Installing is just reverse of removal. DON'T FORGET TO REMOVE NEGATIVE BATTERY CABLE AGAIN. ALSO, PEOPLE MEAN WELL SOMETIMES, BUT DON'T DO THAT PERMANENT BYPASS STUFF! THE ECU IS IN THERE FOR A PURPOSE--IF YOU BYPASS IT, THE FUEL PUMP RUNS ON HIGH ALL THE TIME AND WEARS OUT! THEY COST ABOUT $295.00. I have a 92 Lexus SC 300 that has been giving me fits and by talking to Lexus mechanics at the dealership I learned how to do this, so I am passing it on to you and whoever has the same problem! I also have a 1991 LS 400 4 door Deluxe that I am having tail-light problems with, so if anybody reading this knows anything about that E-Mail me at charliehesterjr@att.net. Good Luck! Oh, by-the-way, looks like I have found me an ECU on E-Bay for about $35.00 including shipping!