:::RHMT::: Real Home Made Turbo
General Category => Hybrid/Tech => Topic started by: Panis on September 29, 2009, 03:07:27 AM
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Have searched this site and various other sites can't find anything solid. Can someone give a rn down of how to wire up heavier gauge wire to a new pump I'm about to install?
I've read that you use stock wire to he relay and heavier gauge to the pump, but i still do t grasp exactly what I'm suppose to do...
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run a constant 12 volt to one side of the relay, run the other end to the pump, use the stock fuel pump power wire to switch the relay on. the power going to the relay and from the relay to pump should be whats heavier gauge.
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Ok that makes sense
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http://www.raktron.com/fuel/rewire1.html (http://www.raktron.com/fuel/rewire1.html)
writeup to use as a guide.... i just did mine...
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Thanks
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run a constant 12 volt to one side of the relay, run the other end to the pump, use the stock fuel pump power wire to switch the relay on. the power going to the relay and from the relay to pump should be whats heavier gauge.
Fail.
http://www.raktron.com/fuel/rewire1.html (http://www.raktron.com/fuel/rewire1.html)
writeup to use as a guide.... i just did mine...
Fail.
The unibody is a bigger restriction than the factory power wire.
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run a constant 12 volt to one side of the relay, run the other end to the pump, use the stock fuel pump power wire to switch the relay on. the power going to the relay and from the relay to pump should be whats heavier gauge.
Fail.
http://www.raktron.com/fuel/rewire1.html (http://www.raktron.com/fuel/rewire1.html)
writeup to use as a guide.... i just did mine...
Fail.
The unibody is a bigger restriction than the factory power wire.
elaborate
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Doing this you're providing a larger diameter wire for current feed... but the pump still gets grounded to the chassis with the stock puny wire. A proper rewire involves running another wire for the pump ground back to the battery, ecu ground, anywhere is a better ground than 8 feet away from the ecu through 14ga wire (the piece from pump to chassis ground) through rusty, painted, crap Jap steel.
+1
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Thanks. Glad I found that out before I installed and re-wired.
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Unibody is a collection of cracked-after-ten-years-and-now-rusty spot welds. Coated with insulators like seam sealer and paint, and with age rust. Crap.
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mine uses the same 10g i wired the pump for as the ground. and it does to the same grounding bolt as my amp.
last time i did a rewire on my car (my CX) i had like 1.5v more at the fuel pump housing at idle over my stock wiring.
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mine uses the same 10g i wired the pump for as the ground. and it does to the same grounding bolt as my amp.
last time i did a rewire on my car (my CX) i had like 1.5v more at the fuel pump housing at idle over my stock wiring.
Volts dont mean shit u Noob check the AMPS
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mine uses the same 10g i wired the pump for as the ground. and it does to the same grounding bolt as my amp.
last time i did a rewire on my car (my CX) i had like 1.5v more at the fuel pump housing at idle over my stock wiring.
Volts dont mean shit u Noob check the AMPS
Yeah, because voltage and current flow are not related at all...
:?:
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Your volts go up because there aren't any other devices leaching current from the fuel pump feed. Checking voltage with a dedicated line to the pump means you aren't getting other devices leaching current, dropping voltage. Battery to pump has nothing hooked to it when checking voltage (breaking the only circuit on the line). You're seeing exactly what the pump sees before current leaks into it. Also some of it is larger wire has less resistance to a degree, but more of it is leaking current. A 20ga wire would also show 14 or 15v. Current leak + smaller wire + other shit taking from a hot line = drop in voltage and available current.
Unless I am misunderstanding your post:
I don't think you understand how voltage drops work if you think that feeding a fuel pump with a 20 ga wire 15 feet long will not yeild a lower voltage at the pump. There most certainly will a voltage drop across the wire because of internal resistance and the amount of current draw from he pump itself.
E = I * R applies very well for what we are talking about here. A wire with no current flowing though it will have no voltage drop.
We can go into more detail if needed.
IF you check the voltage at the pump WITH IT RUNNING, then you are in fact seeing the effects of running a dedicated larger diameter wire.
With that said, the point about the chassis being a piss poor conductor is totally relevant. If you want to see how shitty it is, then put the maximum load that you can on your electrical system and perform a voltage drop test between you fuel pump's negative terminal and the negative battery terminal. Hell, just look at the pathetic ground straps and ground connections from the factory.
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ok
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Yes, I get this. I'm talking about more than that. Copper of length 8 feet long at both 20ga and 12ga will yield similar voltages at the ends. The resistivity of copper is pretty low and 12V is pretty high V (I'm used to dealing with microvolts in a lot of cases at school).
What I am saying is most of the voltage drop is because of other shit being on that feed line, pulling current, and since the feed wires are relatively small there is significant voltage drop. Someone can check the wiring diagrams... I'm too lazy... to verify what else may or may not be connected to the feed for the fuel pump. I know essentially everything is because everything connects to the battery, but a direct line will always result in less voltage drop since current isn't leaking. The battery is a big source/sink that can put out a ton of current.
More detail about V=IR is not necessary... lol.
;D
I was thinking more in terms resistance with relation to resistivity and the dimensions of a conductor (R = p * (L / A ). lol
You are right, the voltages at the ends will be similar, as long as the current flow in the 20 ga wire does not reach a point that the wire's internal resistance becomes significant.
We are not talking about mV or even uV here, nor are we talking about mA or uA, but the same rules apply.