R33 fuel pump mod question

[Ty1]

Hey everyone. Just in the process of doing the fuel pump mod on an r33 gtst and just want to double check that im doing it right as im pretty bad when it comes to anything electrical lol ive searched all over the forums but im wanting to be 100% sure. So im basically left with these 2 wires...a red wire which im sure splices into the blue (power) wire which ive already snipped. But i just need confirmation that the red and black wire does splice into the white (ground) wire as these instructions i have specify to splice into an ecu signal wire, not a ground wire. Ive attached pictures of my setup so any input would be greatly appreciated [emoji5] thanks!

[vxsr33]

With the grey wire (ground) cut it in the middle the splice in a wire going to a ground source in the boot. On my s2 r33 the ground was grey and active light blue

[Duncan]

That diagram is not for a skyline, right?  In our system the ECU signal is negative not positive. It goes to a relay which goes to a variable resistor which changes the pump speed when at idle, and then to the pump.

If you are trying to simplify you need to find the original fuel pump relay (I think it is under the carpet in the boot where the boot lock is), find which wire into that has earth for about 5 seconds after you turn the ignition on but then it stops.

Use that wire to 85 on your diagram as the - relay source. Connect 86 to the same wire that comes from your battery (it is the + relay source). 87 connects to fuel pump + as shown. fuel pump - should go straight to a good earth as shown on the diagram

Sorry I don't know wire colours, they change between models anyway, but what I wrote works for all R chassis.

Wired up this way you get full voltage all the time, and the fuel pump is still controlled on and off by the ECU which is important for safety. The diagram you had assumed a + source from the ECU.

[Ty1]

In relation to that grey wire i didnt think i would need to splice into it as the relay has a ground cable which ive already attached to the chassis (picture attached) Thanks for your informative reply duncan. From all the posts ive read about the fuel pump mod there hasnt been any mention of tapping into the fuel pump relay. I was under the impression that i only had to tap into those two bigger wires coming out of the fuel tank. Is the fuel pump relay the only safe way of doing it?

[Duncan]

Well if you take the current + to the fuel pump as your trigger to your new relay everything will still work...but you will still be running through the old fuel pump relay unnecessarily. It's not a big deal but if it fails you will lose fuel even though it's not serving any useful purpose.

[Ty1]

Ahh ok i understand now [emoji5] will let everyone know how it goes [emoji106]

[Ty1]

Mission accomplished! Thanks guys for your help [emoji5]