 Fuel Pump Relay mod |
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 Jun 7, 2011 - 12:55 AM
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Enthusiast  Joined Aug 15, '10 From Nevis, West Indies Currently Offline Reputation: 0 (0%)  |
Anyone did this? to make the pump run at a constant 12v? any improvements if so?
-------------------- 1994 Toyota Celica GT-Four ST205 Turbo 4WD, Black
Nevis, West Indies |
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Jun 7, 2011 - 10:06 AM
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Enthusiast Joined Aug 15, '10 From Nevis, West Indies Currently Offline Reputation: 0 (0%) |
QUOTE (cax_11 @ Jun 7, 2011 - 12:55 AM)  Anyone did this? to make the pump run at a constant 12v? any improvements if so? nobody did this mod??? -------------------- 1994 Toyota Celica GT-Four ST205 Turbo 4WD, Black
Nevis, West Indies |
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Jun 7, 2011 - 11:34 AM
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 Enthusiast Joined Aug 31, '02 From Philadelphia, PA Currently Offline Reputation: 8 (100%) |
I did.
http://www.6gc.net/forums/index.php?showto...777&hl=fuel Its a good idea to do and I saw more consistent voltage through the efi system and the fuel pump circuit. Just make sure you use a higher quality fuse holder than the one I have pictured, because the one in the photos (purchased from walmart) ended up catching fire! I replaced it with a good quality radioshack fuse holder and never had a problem since. -------------------- 15PSI - 30MPG - Megasquirt Tuned
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Jun 7, 2011 - 6:58 PM
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Enthusiast Joined Aug 15, '10 From Nevis, West Indies Currently Offline Reputation: 0 (0%) |
QUOTE (lagos @ Jun 7, 2011 - 12:34 PM) I did. http://www.6gc.net/forums/index.php?showto...777&hl=fuel Its a good idea to do and I saw more consistent voltage through the efi system and the fuel pump circuit. Just make sure you use a higher quality fuse holder than the one I have pictured, because the one in the photos (purchased from walmart) ended up catching fire! I replaced it with a good quality radioshack fuse holder and never had a problem since. good write up but, i'm a bit lost on how this is actually done.. the way i understand is that you cut a wire on the fuel pump resistor and bypass it so it runs steady 14.5 instead of 9v at idle and part throttle and 14.5 at wide open -------------------- 1994 Toyota Celica GT-Four ST205 Turbo 4WD, Black
Nevis, West Indies |
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Jun 8, 2011 - 1:13 AM
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Enthusiast Joined Aug 31, '02 From Philadelphia, PA Currently Offline Reputation: 8 (100%) |
QUOTE (cax_11 @ Jun 7, 2011 - 7:58 PM) QUOTE (lagos @ Jun 7, 2011 - 12:34 PM) I did. http://www.6gc.net/forums/index.php?showto...777&hl=fuel Its a good idea to do and I saw more consistent voltage through the efi system and the fuel pump circuit. Just make sure you use a higher quality fuse holder than the one I have pictured, because the one in the photos (purchased from walmart) ended up catching fire! I replaced it with a good quality radioshack fuse holder and never had a problem since. good write up but, i'm a bit lost on how this is actually done.. the way i understand is that you cut a wire on the fuel pump resistor and bypass it so it runs steady 14.5 instead of 9v at idle and part throttle and 14.5 at wide open Yes, but i went a step further than that. Basically, from the factory the fuel pump has a low/high voltage mode...but thats not really the problem. The real issue is that: 1. the fuel pump gets power from the EFI circuit, that is already burdened with running your ecu, various sensors, etc... 2. the factory wiring for the fuel pump is very thin gauge, and that can cause voltage drops to the power hungry aftermarket fuel pumps that we use. So basically, my write up says to take power for the fuel pump directly from the battery with all new thick gauge wiring, and use the old fuel pump/efi circuit to trigger a relay to turn the new circuit on/off. Makes sense? -------------------- 15PSI - 30MPG - Megasquirt Tuned
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Jun 8, 2011 - 1:18 AM
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Enthusiast Joined Aug 31, '02 From Philadelphia, PA Currently Offline Reputation: 8 (100%) |
I just noticed that you own a gt4. In all honestly, you really don't need to do this mod unless you upgrade to a higher than stock flowing fuel pump...and as long as you are on the stock injectors/ecu, there is no need to do that.
The factory fuel pump in your car will work fine with the factory wiring. And the low/high mode probably helps gas millage, and to lower the overall drain on your electrical system. -------------------- 15PSI - 30MPG - Megasquirt Tuned
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Jun 8, 2011 - 3:28 AM
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 Enthusiast Joined Dec 15, '02 From Tasmania(Australia) Currently Offline Reputation: 0 (0%) |
Did you upgrade the fuel pumps earth?
-------------------- ST205 Group A Rallye GT-Four, #61 of 77............600hp GT3582r
GRX133 Toyota Mark X 350s  |
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Jun 8, 2011 - 4:10 AM
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Enthusiast Joined Aug 15, '10 From Nevis, West Indies Currently Offline Reputation: 0 (0%) |
QUOTE (lagos @ Jun 8, 2011 - 1:18 AM) I just noticed that you own a gt4. In all honestly, you really don't need to do this mod unless you upgrade to a higher than stock flowing fuel pump...and as long as you are on the stock injectors/ecu, there is no need to do that. The factory fuel pump in your car will work fine with the factory wiring. And the low/high mode probably helps gas millage, and to lower the overall drain on your electrical system. Ok then, thanks for the info  from more research I learned this was done when the resistor goes bad, as it would drop off voltage between the transition from 9-14, cause a lil bog down before it switches to 14, but I think it would probably cause a little over fueling at low rpm and at idle. 
-------------------- 1994 Toyota Celica GT-Four ST205 Turbo 4WD, Black
Nevis, West Indies |
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Jun 8, 2011 - 4:15 AM
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Enthusiast Joined Aug 15, '10 From Nevis, West Indies Currently Offline Reputation: 0 (0%) |
QUOTE (Cuts_the_Pilot @ Jun 8, 2011 - 3:28 AM) Did you upgrade the fuel pumps earth? No, from what am seeing, thats the earth for the relay. -------------------- 1994 Toyota Celica GT-Four ST205 Turbo 4WD, Black
Nevis, West Indies |
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Jun 8, 2011 - 6:51 AM
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Enthusiast Joined Dec 15, '02 From Tasmania(Australia) Currently Offline Reputation: 0 (0%) |
I couldnt see any upgrade either, hence the question.
-------------------- ST205 Group A Rallye GT-Four, #61 of 77............600hp GT3582r
GRX133 Toyota Mark X 350s |
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Jun 8, 2011 - 6:42 PM
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Enthusiast Joined Dec 8, '03 From Lancaster CA Currently Offline Reputation: 6 (100%) |
ha ha ha Supra guys have been doing this for years!
-------------------- 2001 Celica GT-S Turbo
1997 Supra TT 6speed 1997 Celica 3MZ/1MZ swap 1990 Celica All-Trac |
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Jun 8, 2011 - 6:45 PM
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Enthusiast Joined Aug 15, '10 From Nevis, West Indies Currently Offline Reputation: 0 (0%) |
QUOTE (Smaay @ Jun 8, 2011 - 6:42 PM) ha ha ha Supra guys have been doing this for years! Are there any performance gains? -------------------- 1994 Toyota Celica GT-Four ST205 Turbo 4WD, Black
Nevis, West Indies |
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Jun 8, 2011 - 7:20 PM
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Enthusiast Joined Dec 15, '02 From Tasmania(Australia) Currently Offline Reputation: 0 (0%) |
QUOTE (Smaay @ Jun 8, 2011 - 4:42 PM) ha ha ha Supra guys have been doing this for years! Would they like a medal? -------------------- ST205 Group A Rallye GT-Four, #61 of 77............600hp GT3582r
GRX133 Toyota Mark X 350s |
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