Club Lexus Forums - View Single Post - SC300 12v Fuel Mod w/ Pictures

LyFeWoRx · 06-30-07, 01:48 PM

Mod Location:
The Fuel Pump ECU is located under the driver side rear qtr window.

Reason:
This mod is very easy - I did the mod because I was having Warm Start problems with my SC300, the car would start up then die (This would happen 10+ times in a row) This mod fixed my problem - everything works perfect now. This will also help when I go NA-T , I will have a step by step thread on that as well.

Vehicle Used:
This car is a 1992 SC300, Auto

Total Mod Time:
45 Mins

From MKIV.com

The Problem:
When modifications are made to the car to increase boost pressure and engine breathing ability, some owners have experienced detonation around 4000 rpm, as the 2nd turbo builds boost and comes on line. Usually, this detonation disappears above 5000 rpm. The problem is, the fuel pump is still in "low speed" mode around 4000 rpm's, but the performance modifications have increased fuel demand to the point of "outrunning" the low speed operation. By 5000 rpm, the fuel pump ECU has caught up and switches to high speed operation and all detonation disappears.

The Solution:
There is an easy way around this. You can wire a 12 volt signal directly to the fuel pump, effectively bypassing the fuel pump ECU so that the fuel pump is always in high speed operation. The TT Supra is one of only a few cars that has this dual mode of fuel pump operation, whereas most cars always have 12 volts to the fuel pump. This mod is completely safe. You are basically just turning your complicated fuel system into a basic, Camry style fuel system. You may shorten the life of your fuel pump from say 20 years down to 18 years, but nothing to worry about in the short term. I've personally had mine hooked up this way for over 2 years now without any troubles.

I hope this helps anyone looking to do the 12v fuel mod or starting issues.

Start with the rear seats.

Pull up on the front of the rear seats to remove the bottoms.

Rear seats removed

Remove the 3 bolts holding the rear back panel down. (12mm)

Rear seats removed

Remove 2 push tabs from the panel under the driver side qtr window.

06-30-07, 01:48 PM	#1
LyFeWoRx Pole Position Garage is empty, add now Trader Score: (0) Join Date: Jul 2006 Location: WA Posts: 217	SC300 12v Fuel Mod w/ Pictures - FAQ Mod Location: The Fuel Pump ECU is located under the driver side rear qtr window. Reason: This mod is very easy - I did the mod because I was having Warm Start problems with my SC300, the car would start up then die (This would happen 10+ times in a row) This mod fixed my problem - everything works perfect now. This will also help when I go NA-T , I will have a step by step thread on that as well. Vehicle Used: This car is a 1992 SC300, Auto Total Mod Time: 45 Mins From MKIV.com The Problem: When modifications are made to the car to increase boost pressure and engine breathing ability, some owners have experienced detonation around 4000 rpm, as the 2nd turbo builds boost and comes on line. Usually, this detonation disappears above 5000 rpm. The problem is, the fuel pump is still in "low speed" mode around 4000 rpm's, but the performance modifications have increased fuel demand to the point of "outrunning" the low speed operation. By 5000 rpm, the fuel pump ECU has caught up and switches to high speed operation and all detonation disappears. The Solution: There is an easy way around this. You can wire a 12 volt signal directly to the fuel pump, effectively bypassing the fuel pump ECU so that the fuel pump is always in high speed operation. The TT Supra is one of only a few cars that has this dual mode of fuel pump operation, whereas most cars always have 12 volts to the fuel pump. This mod is completely safe. You are basically just turning your complicated fuel system into a basic, Camry style fuel system. You may shorten the life of your fuel pump from say 20 years down to 18 years, but nothing to worry about in the short term. I've personally had mine hooked up this way for over 2 years now without any troubles. I hope this helps anyone looking to do the 12v fuel mod or starting issues. Start with the rear seats. Pull up on the front of the rear seats to remove the bottoms. Rear seats removed Remove the 3 bolts holding the rear back panel down. (12mm) Rear seats removed Remove 2 push tabs from the panel under the driver side qtr window. __________________ 1995 Pearl White SC300 5 Speed. (Sold) 1992 Pearl White SC300 Auto (NA-T Project) Last edited by LyFeWoRx; 06-30-07 at 01:59 PM.