Missing In Low Revs In 1St, 2Nd And 3Rd After Fuel Pump Install

[Stock e-Tune]

Installing a 7v relay to bypass the pump drive control circuits is a quick fix if the module is faulty.

[rondofj]

The horn relay I got has 5 pins - 30, 85, 86, 87and 87a - there was also a 4 pin one but it had its own fuse in the fuse holder - I already have the wire from battery to boot with fuse holder (50A fuse inside) - I need to get a large 30A fuse which I couldnt find. Is this horn relay and the relay base (connector) sufficient?? The thickest connector wire is only rated at 15A and 105 degrees, 600V and 14AWG whatever that is.. And the ground eye connectors are the small blue ones, also got similar size wire bullet terminals too.

Please advise if these items r ok - and which pin shud I use for pump +ve 87, not 87A?? 87A is closed and 87 is open.

CLICK TO ENLARGE

Horn Relay Base

This is a plug in base with cable attached.- Suits SY-4068 and SY-40

[DVS JEZ]

87 and 87a are both positive outs. U can use either. They are the same thing

[89CAL]

Nah there not. 87 will be normally open and 87a will be normally closed

Or the other way around..... Think I got it right but

[DVS JEZ]

Your right man. My bad.

When there is 87a it is connected to 30 even though the coil is not energised. But when the coil gets energised then 87a is not connected.

[rondofj]

true, 87a is closed and 87 is open as I stated above, does it still mean I can use either?

[89CAL]

no

If you use the normally closed circuit, your fuel pump will prime ALL the time until a circuit is passed through the coil (which will be when you turn the car on and the fuel pump circuit is energised) then the fuel pump will turn off.

Normally open is in the open (no circuit) condition when there is no signal

Normally closed is closed (complete circuit) condition when there is no signal

Your signal in this case is your original fuel pump wiring engaging the coil.

Basically if you imagine that the drawing I posted has a circle with 87a where the left hand circuit is incomplete then thats what the 87a will be. Make sense?

[rondofj]

thanks man, u saved me from miswiring! Now I know I will have to use pin 87 (normally open) so the pump dosent prime when the car is off!

[89CAL]

Yeah I'm pretty sure thats the right way. Worst case scenario, if you hear the pump priming while the cars off or anything weird like that then change to pin 87a. But I Think 87 is normally open

[rondofj]

yes its open, I can confirm that from the diagram on my relay - 87a is connected to the other side of pin 30 (battery current draw) and 87 is not connected to anything.

cheers Ron

[DVS JEZ]

To save confusion next time get the 4 pin. Only 1 87 then.

Have u fitted it all

[rondofj]

havent fitted yet, goin in tomorrow nite or sat, so I dont get stuck with a car that cannot drive to work!

[rondofj]

Have just wired in my fuel pump at an automotive shop and its done wrong because it keeps running when ignition is off and they only used one of the 2 wires (the yellow/ black one) goin onto pump and hooked both ends of that onto relay 87(goin to pump) and 85 (ecu ign signal). The other wire (green/white) goin to pump from ecu is untouched. Relay pin 86 is earthed by itself only.

Pump has 2 wires - green/white and a yellow/black which comes from a splitter hooked to 3 yellow/black wires. Are these the ground wires or is the green/black ground?? Is the r34 +ve or -ve trigger??

Good news is that now the car is back running smooth as ever and all the missing/pops/power loss/hesitation in low rpms is GONE..

But I still have to take off relay everytime I park or else the pump keeps running! Someone please hepl..

[rondofj]

I mean someone please help lol..

[KiwiRS4T]

There are two wiring "how to"s in the DIY section. The relay switching signal comes from the original wire, There should ideally be a new heavy duty wire coming from the battery and that goes through the relay to the pump. Take it back to the shop that did it and ask them to fix it (for no extra charge).

[rondofj]

There is a heavy duty wire with 30A fuse from battery to pump. But as above, the wiring is just wrong, I know u have to cut both ecu-pump wires and hook them to relay and earth/chassis - in my case as I mentioned above only one of those wires is cut. The workshop guys obviously are not too clever, so I wouldnt let them fk it up some more, besides they closed now.. Its a simple wiring I know, just gotta know which wire is ground and which is original switch wire..

[rondofj]

It would help big time if someone can post which color code is which wire on R34s. I have 3 yellow/blacks goin onto one yellow/black that goes to pump. And a green/white that goes to pump. Plus 2 other wires purple and black, goin onto fuel sender..

[rondofj]

anyone??

[rondofj]

took it for a drive - better than ever - too much wheelspin when goin on boost which is too dangerous and a big thumbs down - even goin straight downhill - kind of wet road (i know) it wheelspins in 2nd.. I think I have less than/around 220rwkw on my 12psi neo engine, a lot of u guys would class that as pretty underpowered, yet how come most of u in the 270 and up rwkw range are NOT complaining about wheelspin????

Maybe its to do with my HARD cusco rear coilovers??? - not enough grip??? Front is the same tho not so hard..

But first things first, someone please tell me the color code for the r34 fuel pump wiring and which ones the trigger?? my wirings still not proper for now - refer above posts..

thanks

[DVS JEZ]

U should come for a drive to the coast so i can fix it up for u.

Will only take u an hour to get here. Why didnt u give it a go yourself