I check fuel pump voltage and it drops to 8volt. I see all the threads for pump re - wire and i have some questions.
Original relay and all original wires styas without any mods? Only thing that i should do is to unput original wires from the pump and connect it to my second relay(the new one). After that from battery negative - directly to pump and plus+ from battery to 25amp fuse, from fuse to new relay and from new relay to the pump

 

https://passionford.com/forum/genera...ed-please.html

 

i had asking for original fuel pump wires and relay! Should i do any mods except disconnect plus and negative - from fuel pump and connect it to my new relay

 

on the relay 86 - i should connect existing fuel pump wires, but i cant uderstand - both wires plus and negative minus to terminal 86 or only plus wire. Original fuel pupm wire - black and red is negative one ?

 

Black and red is a positive signal from the original relay to the fuel pump, BROWN is earth, on fords of this age BLACK is always a switched live.
On the new relay, 30(or 30/51) is battery input through fuse by battery, 87 is output to pump, 85 and 86 are earth and live(trigger) from existing fuel pump live wire.
85 and 86 can be reversed doesn't matter still works perfect.
I found just behind the rear seat upright metalwork there is a 8mm hole, so use a relay holder and relay here, so that when at shows etc you can simply pull the relay out for a bit of added security, make sure the original live is taken after the cut out switch, as this needs to remain in the circuit, you will need to use the existing connections though if on a 044(std) pump just chop about 6" from end and join to new wires.
tabetha

 

i rewire fuel pump and i ve got at iddle 12,6v at the pump 13v at the new relay and 13,8 at battery! I cant understand why i lose 1,2v? is it 12,6v enouch to drive or i should search where is my problem?

 

Did you use a good earth, I.E the battery neg itself not just earthed onto a rusty floor?

Martin

 

If you dont understand get a person that does or you might regret it !

 

battery 13,8v at iddle , fuel pump 12,94v after rewire.
Should i do something or with this voltage 12,94 it will be fine?

 

12.94 will be fine, the main point is it will MAINTAIN that 12.94 voltage even when drawing a heavy current(amps), the pumps are designed at 12V anyway, but so long as mapped or chipped ok at that will be fine, slightly more drop than I'd expect but no problem, as it will maintain it even under load whereas a old wiring set up will drop even further under load.
tabetha

 

no, i use earth from chassis. is the voltage be better if i use earth directly from battery

 

ALWAYS use the battery pole/post for best results/lowest resistance, the more connection points you can eliminate the better, even a brand new joint wil have resistance.
New earth wire all the way from battery is the way to go.
tabetha

 

Yes as this is the path of least resistance, but providing is good earth should suffice some just use an old rusty mounting, there is nothing wrong with those readings so long as they are maintained with the pump UNDER load.

Martin

 

i was too much of a thick shit to work all that out myself so i bought my re-wire kit off ebay from these guys

http://cgi.ebay.co.uk/Cosworth-Group...QQcmdZViewItem

except mine has standard pump connectors

 

i will connect new earth directly from battery

 

with new earth from battery voltage drops. I think its better as close as possible to pump to take earth. To new relay trigger is live from original pump relay and earth from original relay isnt it ?

 

I would have made the loom with a close earth point and a battery one !

 

i try this, voltage is exactly the same as with only one earth cable from chassis to pump earth

 

Voltage is not the concern here, what it is whilst idling/under no load will be VERY different to that shown when under high CURRENT(amps) if all is not well wiring wise, where it could drop markedly.
The reason you don't take to the body/close point although easier is resistance, the more connection points you can eliminate between the pump and battery the better it will be, it will also NOT be prone to any corrosion issues, that could be encountered.
I have seen them earthed to the spare wheel well with a self tapper before now though, it's your car of course so up to you, but can't understand 1/2 a job with you doing the live, the earth is just as important, and even easier.
tabetha

 

I have just purchased a loom for this upgrade 2wd saph i,m under the understanding that the original earth from original relay either needs to be taped up or earthed to chassis. Then your loom you make or buy will have its earth which as said can go direct to batterie or body and pump earth. I had a good look at my cars wiring today and it seems straight forward being a novice. Keep your cut off switch in circuit as usual , on my car the original live going to the cut off switch goes direct to from here to + pump . On that part of the live wire (black/red) Is where you need to feed relay live (original pump live) on ur new relay pin 86 (ignition live). Earth/ground pin 85 , pin 30 is 12v fused direct from batt , pin 87 live to pump.

I do hope im right lol please correct me if not
edit- pin 85 earth ground ur choice , either to body or batterie

Mike

 

13.30v at pump , 13,40 at relay new live cable, and something really interesting - 13,73v at original fuel pump wire, which i use for relay trigger.
Battery is 13,9v at iddle

 

after fuel pump rewire my fuel pressure increase from 2,9 bar to 3,2 bar at iddle without any changes at fuel regulator! Is this normal?

 

Thats an interesting find mate, seems like its benifited from the re-wire indeed

 

Correct with terminal numbers etc.
tabetha

 

sorry if stealing thread, tabs what did you do with the original earth wire for pump ? My guess is you took the old original relay out and have direct feed to new relay via ECU ??

 

Old earth was cut off and loom taped up, I dispensed with the whole of the original stuff, apart from using the red/black wire to feed the new relay located in the boot, other end of black/red that came from original relay was chopped at relay, and joined to my emerald K3 ecu as this feeds the fuel pump, took out the oe relay and job done, made a simple loop[ of wire with a male spade on each end, in case of relay failure, can always bridge 30 and 87 so the pump runs continuous, also good for fault finding at times.
tabetha

 

Are these just plug & play? I'm not very experienced when it comes to electrics

 

Yes and have all connectors ready to connect, in that pic it shows they even label the wires for you.

Martin