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Bypass Fuel pump relay question

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Old Apr 15, 2023 | 11:36 PM
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Bypass Fuel pump relay question

Sorry to be a burden, but if I do this


to my fuel pump relay located in the very front of the car will it simply bypass or tell the fuel pump 2 stage resistor to stay in full 12v mode? Or whatever the higher voltage is?

I saw a thread about this, but I wanted to confirm as the person who posted this pic said this is how he did it...... he also said it will burn out the resistor.. I don't think that's what he actually meant so I wanted to confirm this with someone. I don't want to burn out my 2 stage resistor, but I want it to stay full "high" mode.
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Old Apr 16, 2023 | 09:54 AM
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OK, just looked at the wiring diagram in the shop manual, section B-1a.

The circuit opening relay is the first relay in the fuel pump circuit, it goes from there to the fuel pump relay which is in parallel with the fuel pump resistor. If the fuel pump relay is open, all current goes through the resistor and you get 9v. If the relay is closed, all current goes through the fuel pump relay (path of least resistance) and you get 12v.

The fuel pump relay is in the front relay box, left most relay. If you jumper that so that it acts like the relay is always active (closed) you are good to go.

BTW hope you are at DGRR this year!

Dale
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Old Apr 16, 2023 | 10:42 AM
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This one correct? I just remember reading someone blew up their resistor by jumping this. I don't want to blow anything up lol. This is not a high amp or anything. I see nothing wrong with this, but I just wanted to double check with you guys.
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Old Apr 16, 2023 | 11:40 AM
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Originally Posted by Testrun
This one correct? I just remember reading someone blew up their resistor by jumping this. I don't want to blow anything up lol. This is not a high amp or anything. I see nothing wrong with this, but I just wanted to double check with you guys.
Then, maybe, don't do this? If you're unsure of what is what, and Dale's detailed answer isnt enough for you to understand, just put the circuit opening relay back and run this stock.
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Old Apr 16, 2023 | 12:14 PM
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Originally Posted by quichedem
Then, maybe, don't do this? If you're unsure of what is what, and Dale's detailed answer isnt enough for you to understand, just put the circuit opening relay back and run this stock.
It never hurts to hear it is plain english. I haven't had a chance to look at the diagram. If I could run it as stock I would leave it alone. I am trouble shooting something.

I say in plain English because following an old thread someone I believe misspoke (or mistyped in this scenario) and said he burned his resistor. Again, I want to make sure it won't burn it. Looking at diagrams and having a general understanding of this I see no reason why it should. Asking people who have a better than general understanding is a safer bet.

Last edited by Testrun; Apr 16, 2023 at 12:16 PM.
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Old Apr 16, 2023 | 05:06 PM
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The person that blew the resistor probably jumped the wrong 2 wires. That will be the main thing to make sure the correct wires are jumpered.

If you do it right it will just run like the car is in 12v mode all the time, that's it. The resistor will still be there but won't be doing anything since it's bypassed.

Dale
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Old Apr 16, 2023 | 05:12 PM
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Originally Posted by DaleClark
The person that blew the resistor probably jumped the wrong 2 wires. That will be the main thing to make sure the correct wires are jumpered.

If you do it right it will just run like the car is in 12v mode all the time, that's it. The resistor will still be there but won't be doing anything since it's bypassed.

Dale
Thanks. I am curious if my relay with the sakebomb kit is/was having issues with the voltage jumping back and forth causing it to heat up. I know the coil operates with 12v... if it is down to 7 or 9 (forgot which one) maybe it could be causing issues. I will jump this and see... Inshould probably change the relay at this stage anyway since the fuse holder melted. Thanks again for the help.
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Old Apr 16, 2023 | 06:24 PM
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Curious what sakebommb it are you trouble shooting? coil packs?
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Old Apr 16, 2023 | 07:18 PM
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Originally Posted by era1oner
Curious what sakebommb it are you trouble shooting? coil packs?

I am trouble shooting their fuel pump rewire harness. I believe they are getting their power for the coil in the relay from the 2 step resistor and I want to bypass it to have a constant 12v.
The 50 amp relay in the harness is heating up and I'm not sure why. I am swappimg it out, but want to see if this fixes the problem. It is a Song Chaun relay.... when bosch just isn't good enough lol
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Old Apr 16, 2023 | 09:12 PM
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The circuit path is not terribly hard to follow, from the battery to the fuel pump. I went through the trouble when I was having a somewhat similar issue. If you're fuel pump, or something else, is drawing too much amperage, that's a big problem. The solution to run the pump wide open, all the time, won't do you any favors, though. Best to find the root cause in case it's something significant. Treating symptoms with Sakebomb's harness may not actually solve the real problem.
All this to say that I suggest you thoroughly troubleshoot the system before implementing workarounds.
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Old Apr 16, 2023 | 09:23 PM
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Appreciate it. The Sakebomb's harness was installed about 2 years ago or so.
There isn't too much to really check unless my pump is just going ballistic and pulling more amps than it's meant to. Denso supra pump with maybe 7-8k miles on it. Shouldn't pull more than 21 amps from what I understand. All the wire is beautiful. I have much more copper than I need. The grounds are beautiful. The fuse is now with an excellent quality holder (maxi fuse 30 amp). The fuse and all wires are cool after running wot for laps around the track, the relay ground is solid. The wires to spades in relay are solid. The power to the pump is solid.. Solid I guess until the relay starts heating up.
The relay could have been damaged when the fuse holder melted so it should be swapped regardless.
I see no harm in jumping this for a solid 12v. The pump runs at max regardless of the 2 step voltage so as long as the relay is closed.

Last edited by Testrun; Apr 16, 2023 at 09:27 PM.
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Old Apr 16, 2023 | 09:36 PM
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Originally Posted by Testrun
Appreciate it. The Sakebomb's harness was installed about 2 years ago or so.
There isn't too much to really check unless my pump is just going ballistic and pulling more amps than it's meant to. Denso supra pump with maybe 7-8k miles on it. Shouldn't pull more than 21 amps from what I understand. All the wire is beautiful. I have much more copper than I need. The grounds are beautiful. The fuse is now with an excellent quality holder (maxi fuse 30 amp). The fuse and all wires are cool after running wot for laps around the track, the relay ground is solid. The wires to spades in relay are solid. The power to the pump is solid.. Solid I guess until the relay starts heating up.
The relay could have been damaged when the fuse holder melted so it should be swapped regardless.
I see no harm in jumping this for a solid 12v. The pump runs at max regardless of the 2 step voltage so as long as the relay is closed.
Right on!! Sounds like you've covered bases well. If you were doing more street driving than track, the constant 12V would probably catch up to you in pump wear. In my case, I was trying to run a surge tank setup with over-sized pumps on stock wiring. I did change my circuit opening relay in my troubleshooting process. I hate electrical systems.
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Old Apr 17, 2023 | 03:51 AM
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Originally Posted by quichedem
Right on!! Sounds like you've covered bases well. If you were doing more street driving than track, the constant 12V would probably catch up to you in pump wear. In my case, I was trying to run a surge tank setup with over-sized pumps on stock wiring. I did change my circuit opening relay in my troubleshooting process. I hate electrical systems.
i probably have a better understanding than how I come across, but I don't have a lot of confidence working on electrical. This car is more is more sreet than track, but I already have this setup in place. I am not too concerned for the wear as it isn't driven often, but I am sure it doesn't help the fuel temps much.
I am sure your stock wiring wasn't too happy, lol..

Last edited by Testrun; Apr 17, 2023 at 05:46 AM.
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