ive been reading a few posts when they say trigger wire is this the wire on cranking it powers the relay if so i should be able to use this as a switch live when not cranking theres no power to the pump am i on about the same thing if so finding this wire shouldnt be a problem i can find this with a test light on the old pump relay when cranking the rest of the wireing the relay is straight forward earth supply from bat ect what amp rating relay should i use and what size fuse should i be running im guna use a bit of beefey wire some recon 17amp wire others 30amp i was reading an old post by glenn a sparky had wired his swithed live fom the ignition but as soon as he turned it on the pump was going all the time is yours still the same thanks in advance ray

 

So you use the black with red trace to trigger your relay in the boot terminal 85 terminal 86 to ground.

I used 39amp cable from battery to boot with a 30 amp fuse as close to battery as possible. Connect this cable to terminal 30 of relay.

Then using the same size cable connect to relay terminal 87 to fuel pump live feed.
Again using the same gauge cable connect pump to chassis ensuring good conductivity.

Job done.

MSD sells a kit which will make it easier.
Mine is overkill but a new engine costs more.

 

thanks chap i was thinking of putting the new relay under the dash where the old one is but snip of the old plug find the triger wire that goes to the old relay and use that as a switched live then run some beefy cable back to the pump any good or no

 

Don't touch the original relay. New relay fitted in boot by inertia cut off switch. Really simple.

Are you fitting a 044 pump? As this is easier to fit nice ring terminals and bigger cable.

DO NOT FORGET THE GROUND FROM PUMP....

 

ive fitted a std new pump ive got an earth return to the battery ive done away with the inurtia switch in the boot years ago if i put the new relay in the boot want i have to rely on the old wireing i want to find the wireing at source or i might leave the old relay under the dash still wired and just abandon the wireing but just piggy back the triger wire for the switch live for the new one some say use the black red trace in the boot for the switch live but shorley thats part of the shonkey wireing chaps in our rsoc run 380bhp on std pump thats what there telling me im guna try this way first but probably end up doing what you said thanks for the info it peeps like you make forums like this good

 

Yes, that's the correct way to do it, i.e. use the output from the original relay as the input to your new one.

The old wiring is irrelevant, as it's only powering the relay, not the pump!

The relays ground isn't important, but the pump ground is, otherwise it defeats the object of rewiring!

Martin

 

you would probably regret not having an inertia cut off too, if you have a bump and the fuel reg gets knocked off.

 

I would have to strongly agree with James. I have one in my cortina.

Safety first.

 

Very true, although some did not have them fitted, the 3DR included.

Martin

 

its a good idea to have one. but if its slammed your probably going to have a split tank as soon as the engine stops the triger wires dead. or if your unlucky to roll it they dont run upside down. ive thought about using a pug 306 one there pretty reliable not so tempermental. ive two new ones over the years they seem to be more dangerous with it on i hit a pothole middle lane of the m1 stopped it dead just managed to get it on the hard shoulder some old women nearly rear ended me in town with the other one going over a speed hump

 

i ended up putting the new relay under the dash next to the old one. i piggy backed the triger wire from the old relay to the new one for the switched live and ran new wires back to the pump. im not sure if the black wire with red trace is the actual triger wire it self. when i pulled the old relay from the plug and cranked the engine there was no live on just cranking only when i put the relay back in the black&red became live on cranking. im no sparky though and a month ago i couldnt wire up a relay now ive done two with my group A coil thanks to you chaps

 

There are no switched lives, the ground is switched via the ECU.

Martin

 

Next mod needs to be a fire extinguisher....