adam151082

Ok so i need some help, i bought a after market fuel pump loom for my car and i cant get the fuel pump to prime, theres a switch wire that i need to attach somewhere

The wire labeled "1st" in the picture is the one i was told to use but it wont prime

The wire labelled "2nd" runs the pump constantly with the ignition on

The 3rd (the blue one) does nothing

Rsmat

iTrader: (2)

What's that mess mate ? ... My loom was plug and play no messing with wires just mount relay and thread through car to rear and bolt up ?

tonyRS

Iv just fitted one on my 3 dr like mat said it was plug and play but it did use the switch wire red/black but I did this in the boot not under the dash!? It's made a massive difference too

cossietim

get someone to do a continuity test for ya mate, should find out whats going on then, where you based? apart from under the thumb lol, can probably recommend someone for ya

adam151082

Ive had the dash out lads, hence the mess lol. Theres not that much to the loom theres just one wire that need a switch so the pump will prime.

How does your pump prime or does it run contantly?

Rsmat

iTrader: (2)

Iirc on my loom 10' up from where it bolts to fuel pump I think I cut the plug of the original wire black with red strip and that goes into the tail wire of your new loom and that's the trigger / primer .. I'm 99% sure off top of my head made but just wait
For someone to either correct me or say its ok

adam151082

Anyone esle help??

martysmartie

iTrader: (1)

Usually what happens is the original relay is used as a 'trigger', i.e. it powers the new relay.

By this theory then I THINK what should happen is the output from the old relay, i.e. that used to power the fuel pump (pin 87), connects to the coil on the new relay, i.e. pin 30, as I say check this first as I have never fitted a pump loom!

Martin

adam151082

Can i conect the trigger to the ECU? Wish id bloody left it alone now.

martysmartie

iTrader: (1)

The original relay is connected to the ECU, thats the idea behind using it as the 'trigger', for the new relay, otherwise your pump would run constantly.

Martin

Rsmat

iTrader: (2)

Adam you going to central day tomorrow I'f so ill draw you the diagram

adam151082

No m8, can i conect it straight to the ECU wire? I hate wiring haha

opposite lock

iTrader: (3)

I think its pin 28 on the ecu that would originally trigger the coil side of the o.e fuel relay thus sending 12v positive to the pump.
The o.e relay feed to pump wire (87 i would think) would now become the switch circuit side on your new relay (86&85)and a new direct from batterie 12v+ feed on the other circuit on the new relay 30&87 usually.

Edit . Dam , Sorry I think i maybe wrong about the pin28 fuel trigger going to the coil side of the o.e relay ,and if thats the case yes you could wire the new loom direct to the ecu .

James @ M Developments.

iTrader: (2)

Wiring it to the ecu can mean you will loose the inertia fuel cut designed to cut the pump if you have an accident so I don't advise that
it may well ruin any insurance claim you tried to make should the worst happen and they found out you had disabled the cars safety features, and may even worse cost you a life.

All the YB cosworth cars have a very vulnerable fuel rail which is easily broken in a frontal impact and it was deemed necessary for a fuel cut switch to be fitted in order to meet its type approval. Don't go bypassing it!

That's why with our rewire looms you simply use the old pump feed after its been through the inertia cut switch to trigger the new relay. This way in an impact the fuel pump will stop running.

If I was you I would put it back to std, refit the oe relay, and use the pump feed in the boot to trigger the new relay.

daz1968

As far as I am aware 3 doors don't have a cut out inertia switch, but the pump stops if the engine does as without crank sensor signal it only primes. I wouldn't mess with relay though if you want feed from under dash disconnect where it connects to the car loom behind the glovebox or do as above and just connect it behind jack cover in boot.

James @ M Developments.

iTrader: (2)

If it hasn't got one I would be fitting one if it was mine while I was there.

martysmartie

iTrader: (1)

Correct, 3DR never had one.

Martin

adam151082

So what pin do i conect it to on the ECU?

martysmartie

iTrader: (1)

You don't touch it, it's basically what me and James said, you take your original fuel pump feed, and then connect this to your new relay, AFTER the inertia switch, but you won't have one as you have 3DR, this then acts as a trigger for the new relay.

Martin

adam151082

But i cant find my original trigger, its got my head in bits.

tonyRS

Mate you will (should) have the two wires that go through the boot floor near the back panel, these go to the pump one brown and one red/ black. The new loom will do away with this but you will still have the two above the floor in the boot. Use the red/black and connect these to the "switch" wire on new loom, I didn't do any messing around with original relays/ ecu etc. can you post a pic of your new loom?

tonyRS

Yes mate mines exactly like this!

Rsmat

iTrader: (2)

Ah thought so .. Cheers tony

adam151082

That wouldnt be a problem if i hadnt removed the original wires, i cant see the point in a new loom if im using old wires, plus the trigger switch wire is only long enough to reach under the dash.

I notice your local Tony, are you a auto electrician? I could do with one

Rsmat

iTrader: (2)

The only bit you use that is old is the OE for wire under the back end as the trigger wire .. It's a proven method .. That works .. Did you not get any instructions with your loom and who did ya get it off ?

tonyRS

I'm not an auto electrician mate, Infact Im useless with wiring! Lol. But if your local to me your more than welcome to come and have a look under my dash to see if you can work out where things go.

martysmartie

iTrader: (1)

You don't need to do anything under the dash, the easiest way is to cut your old fuel pump feed and then connect this to the relay.

Since it is only powering the relay, the old wiring is not an issue.

When you say you have removed it have you just cut it, or totally removed it? If the former you could just splice a new length of wire in.

Martin