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Last edited by Papa; 12-11-2017 at 10:05 PM.
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Yes if you add (positive) current to pin 86 you will have continuity thru pin 87 & 30. While pins 85 & 86 are not polarity sensitive DIN standards dictate 85 as negative and 86 positive just the way you drew them. And pin 30 is usually hooked to your power source but will work fine as you've designed the circuits.
Hi Papa. I am not sure the fuel pump will work as you expect it to with the system you have drawn. Cutting the tan jumper wire will remove power from the fuse panel relay that actually turns on the power to the fuel pump, thus, it will not run. If you simply tap into the tan wire your ground will work as drawn BUT, you will not be controlling the pump with the EFI computer! The pump will simply run all the time via the FFR harness if it is wired as directed. The green ground wire from the EFI computer controls the pump by supplying the necessary ground to the relay to make it run. Simply grounding the green wire will do nothing for the pump or the computer. Unless of course I totally do not understand the system!
Last edited by BB767; 12-11-2017 at 10:52 PM.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
Thanks, NAZ & BB767. As I understand (not much at all) what the FAST EFI system wants to do, it appears that the FAST ECM will apply a negative signal on the fuel pump control wire, which I want to turn into a positive signal to power my fuel pump relay.
"Fuel Pump Relay Green wire Negative control side of a relay for powering a fuel pump. Do NOT wire directly to fuel pump."
Could I also just connect the green wire to the existing fuel pump relay ground to accomplish the desired result?
Last edited by Papa; 12-11-2017 at 10:56 PM.
My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
(Most viewed Roadster build thread on this forum!)
Delivered: 6/17/2017
First Start: 12/30/2017
Completed: 12/7/2019
Legal: 1/30/2020
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That’s what I did, it works perfect. Curious to hear what the experts have to say.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
I was trying to explain your recommendation to the guys from FFR and BluePrint and I think I just got myself more confused. I found this discussion on another forum:
http://www.cpgnation.com/forum/threa...p-relay.25663/
It got me thinking of how to create the switch I drew to essentially close the circuit on the existing fuel pump relay using the signal from the ECM.
My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
(Most viewed Roadster build thread on this forum!)
Delivered: 6/17/2017
First Start: 12/30/2017
Completed: 12/7/2019
Legal: 1/30/2020
Member of the Mile-Hi Cobra Club
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Papa
You could also pick up the ground wire from the inertia switch and run it to the efi lead
Rick
That is exactly what I did as that IS the only ground wire for the fuel pump relay.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
You also get to keep the inertia switch in the circuit which is a good thing
Yep. Only drawback that I can see is if there is a problem with the circuit it could be either the inertia switch or the computer but that should not be to hard to narrow down.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
Looking at the schematic for the main harness, that ground is also where all the other grounds in the main harness tie into. So, would I need to cut the ground wire side of the inertia switch and connect that to the EFI control and terminate the other end that runs back to the ring terminal in the foot box?
My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
(Most viewed Roadster build thread on this forum!)
Delivered: 6/17/2017
First Start: 12/30/2017
Completed: 12/7/2019
Legal: 1/30/2020
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Not to hijack the post but since it was mentioned, my inertia switch is mounted with the red reset facing down. Has anyone had any problems with it mounted this way? It is easier to access and reset in this position but I could turn it over if necessary.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
Last edited by BB767; 12-11-2017 at 11:44 PM.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
I would just look at the plug for the inertia switch and determine which wire comes from the relay and then cut the other wire that goes to ground you could ground the unused end if you want to or just seal it with heat shrink tape
Do a lineman splice with soldier and heat shrink tape
I’m not sure about the mounting of the inertia switch
Rick
Last edited by Itchief; 12-11-2017 at 11:54 PM.
My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
(Most viewed Roadster build thread on this forum!)
Delivered: 6/17/2017
First Start: 12/30/2017
Completed: 12/7/2019
Legal: 1/30/2020
Member of the Mile-Hi Cobra Club
Dave's Cobra YouTube Channel: https://www.youtube.com/channel/UCbk...npK1UZHj4R-bYQ
Agora 1:8 Scale Cobra Build: https://thefactoryfiveforum.com/show...l-Build-Thread
My Build Thread: http://thefactoryfiveforum.com/showt...ter-Build-9754
(Most viewed Roadster build thread on this forum!)
Delivered: 6/17/2017
First Start: 12/30/2017
Completed: 12/7/2019
Legal: 1/30/2020
Member of the Mile-Hi Cobra Club
Dave's Cobra YouTube Channel: https://www.youtube.com/channel/UCbk...npK1UZHj4R-bYQ
Agora 1:8 Scale Cobra Build: https://thefactoryfiveforum.com/show...l-Build-Thread
You are cooking with gas now
Good luck
From the reasearch I have done you should not use solder joints on automotive wiring unless you are REALLY good at it. I am not. The same reasearch tells me a well executed crimp connection is a very acceptable second choice. Never had a problem with these in 40 years. Not trying to be contrarian, just stating my opinion.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
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MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
No problem old habits
I soldier and heat shrink connectors and spade terminals also
That sounds like a definitive answer. I’ll get it turned over. Thanks.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
I wish I could make a decent solder joint. Just not patient enough I guess.
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
A pencil soldier iron will work for most connectors except for the ones with large wires
Use a rosin core soldier; tin the soldiering iron tip with soldier and always heat the connector
I tin the wire with soldier before I put it into the connector and then crimp, soldier and heat shrink tape
MK4 - complete kit - Blueprint 427W - Holly Sniper EFI - TKO 600 .64 - 3.55 3 link - 17" Halibrands
Just for reference.. this site has a pretty good selection of standard relay wiring that can accomplish a lot of common circuits.
https://www.the12volt.com/relays/relaydiagrams.asp
The OPs diagrams seems to be a perfect match for this one
https://www.the12volt.com/relays/relaydiagram9.html