Robert@KBXPerformance
04-04-2012, 06:37 PM
I have seen enough people here asking questions over the years of how they should wire their dual fuel pumps setup. I finally decided that since I just completed my custom dual in-tank Walbro setup setup that I would also take the time to make some diagrams since it is all fresh in my memory.
If you plan to activate on of the fuel pumps with a hobbs pressure switch (boost activated) then you will need to install that in-line in the black wire that ground one of the new fuel pump relays. Since you will be splitting the stock cut black ground wire into 2 black wires that will ground each of the new fuel pump relays you will want to put the Hobbs pressure switch in-line with only one of those two wires so the other fuel pump relay still can activate with your ignition turning on.
I decided to use two relays, each powering one fuel pump so that in the case where one relay shit the bed then I could still drive home on the other single pump. You can choose to simplify your wiring a little bit and just run a single relay to power both pumps. Make sure that the relay(s) you use have an amperage rating that exceeds what the maximum amperage draw will be from the pumps. The same goes for the wiring size gauge, as mentioned in the notes section of my diagrams. The amperage rating of the fuses you use need to be BELOW what the rated amperage capacity for the wire/distance you are using to power the pumps but ABOVE the total maximum amperage draw of the pumps you are using. This will allow the fuses to keep the wiring safe so the fuse blows first rather than wire melting because it was pushed past its amperage capacity and will also ensure that you aren't blowing fuses when the circuit isn't even overloaded. See the Ampacity Chart diagram below.
14730
The numbers in the center section of this chart are MAXIMUM distances that size of wire can be routed and still handle the rated amount of amps on the left side.
One other note worth mentioning is that ALL wiring connections inside and outside of the tank should be soldered and with fuel resistant heat shrink tubing protecting them. Try to minimize the spade quick connectors if you can; and DO NOT use butt connectors! You can find this at Napa, it is the semi-clear stuff. The connections are still in the vicinity and if fuel vapor does escape then the tubing won't degrade over time.
Here it is. Let me know if you have any questions. Once I have done more testing and have some more miles on my new setup I plan to post a full HOW TO writeup for building your own DIY dual in-tank fuel pump setup with pictures. That may be in a week or two; we will see. I hope this doesn't appear too much like Greek to some of you guys who are new to wiring because I made this write-up specifically for you. I tried to simplify it as much as I could while still keeping enough detail in so that nothing important is skipped. Enjoy! See diagrams below and zoom in.
14728
14729
If you plan to activate on of the fuel pumps with a hobbs pressure switch (boost activated) then you will need to install that in-line in the black wire that ground one of the new fuel pump relays. Since you will be splitting the stock cut black ground wire into 2 black wires that will ground each of the new fuel pump relays you will want to put the Hobbs pressure switch in-line with only one of those two wires so the other fuel pump relay still can activate with your ignition turning on.
I decided to use two relays, each powering one fuel pump so that in the case where one relay shit the bed then I could still drive home on the other single pump. You can choose to simplify your wiring a little bit and just run a single relay to power both pumps. Make sure that the relay(s) you use have an amperage rating that exceeds what the maximum amperage draw will be from the pumps. The same goes for the wiring size gauge, as mentioned in the notes section of my diagrams. The amperage rating of the fuses you use need to be BELOW what the rated amperage capacity for the wire/distance you are using to power the pumps but ABOVE the total maximum amperage draw of the pumps you are using. This will allow the fuses to keep the wiring safe so the fuse blows first rather than wire melting because it was pushed past its amperage capacity and will also ensure that you aren't blowing fuses when the circuit isn't even overloaded. See the Ampacity Chart diagram below.
14730
The numbers in the center section of this chart are MAXIMUM distances that size of wire can be routed and still handle the rated amount of amps on the left side.
One other note worth mentioning is that ALL wiring connections inside and outside of the tank should be soldered and with fuel resistant heat shrink tubing protecting them. Try to minimize the spade quick connectors if you can; and DO NOT use butt connectors! You can find this at Napa, it is the semi-clear stuff. The connections are still in the vicinity and if fuel vapor does escape then the tubing won't degrade over time.
Here it is. Let me know if you have any questions. Once I have done more testing and have some more miles on my new setup I plan to post a full HOW TO writeup for building your own DIY dual in-tank fuel pump setup with pictures. That may be in a week or two; we will see. I hope this doesn't appear too much like Greek to some of you guys who are new to wiring because I made this write-up specifically for you. I tried to simplify it as much as I could while still keeping enough detail in so that nothing important is skipped. Enjoy! See diagrams below and zoom in.
14728
14729