Power Fc Issue

[Ad's]

After the adventures of my car not shutting down:

http://www.skylinesaustralia.com/forums/topic/365322-rb25det-wont-shut-down/

I ended up giving up for a little while and received a power fc today! My problem is the fuel pump doesn't stop priming it never done this with the standard computer just didn't shut down, and now with the power fc installed it has fixed the shutting down issue but this one has arose.

Any ideas?

Tune on the current ecu?

The RB25DET is a S2 and was a auto.

I had to add a relay so the fuel pump could shut off when i first installed it.

Just seems weired that all of a sudden it has started playing up

Cheers

[DVS JEZ]

So u needed a relay to turn the pump off? This isnt normal. Try removing this and set up the fuel pump so the ecu triggers it on only.

Maybe there was a fault in the stock ecu before

[Ad's]

I wired it up from this:

http://wiki.r31skylineclub.com/index.php?title=Wiring_an_RB25DET_into_an_R31

But as it is used with stock computers i guess it would work fine! Been a aftermarket computer it probally witches the fuel pump on and off differently?

Ill have a closer look and post up what i find.

Cheers

[Dose Pipe Sutututu]

The ECU triggers a -ve signal which activates the fuel pump's relay, you find out many workshops when they wire up cars for transplants earth the fuel pump relay trigger, so as soon as the keys are inserted and switched onto 'ON' the fuel pump primes continuously, nothing wrong but not great when the car gets into a bingle and sprays fuel everywhere.

If you look at my signature below, the RB harness only needs:

- constant +ve

- 2x ignition switched +ve

- fuel pump trigger -ve

Edited June 15, 2011 by johnnilicte

[Ad's]

I'm new to wiring so i feel pretty silly asking questions haha. As far as i know the r31 fuel pump is earthed through the fuse box and the r33 is with the ecu that's why i had to wire in a relay.

So this is how the relay is wired in atm and i wired it with the help of the above link:

The relay has to come out so what do i wire to what or where? Is there a way i can get away with out the fuel pump priming all the time johnnilicte?

If someone could give me a step by step i would be over the moon.

Sorry to be a pain in the ass!

Cheers guys.

[Ad's]

Been thinking tonight about this i havent wired the car just yet just seeing if it would work in other peoples thoughts? Would this be pretty much the same as hard wiring the fuel pump, as i had to wire in a relay to start with because 31's arent the same ecu setup as a 33?

Currently:

With out the relay:

Thoughts?

Adam

Edited June 15, 2011 by Ad's

[QWK32]

first up i'll say i don't know anything about how the powerfc handles the priming of the pump. what i can say is don't wire it directly to the ecu, you'll fry the ecu as its only meant to switch a rely coil, not drive a pump motor.

in the first drawing you posted (post #5) if you can manually ground pin 86 and the pump turn on and off fine. and when you hook it up to the ecu it brings the pump on fine when the ecu is powered up. then wouldn't that lean more towards the ecu itself isn't turning off the pump after a ~3 second prime. do powerfc's even do this?

[Don Dada]

AFAIK the pfc primes the pump for a couple of seconds also and once it worked fine with the stock R33 ecu, I see no reason why it should not work with the pfc

You can test the negative signal from the pfc (pin 18) by using a multimeter putting the neg probe on pin 18 and the pos probe on a constant 12v and turn on the ign and see if you get a 12v supply for a few secs.....If possible diconnect pin 18 from everything else so nothing interferes

If you get a constant 12v your pfc is most likely screwed.

[Dose Pipe Sutututu]

okay, what you could do it wire up a brand new circuit (which is good anyways, since your car's wiring is donkers old)...

use a relay to the pump, but make it click over as a negative trigger.

The PowerFC uses a -ve trigger to activate the pump, it will prime then stop after 1~2 seconds without CAS movement.

But doesn't the HR31 have an existing relay circuit? why could you not use that?

[Ad's]

I will have to try the above posts soon and see what come up with!

johnnilicte i kind of get what you are saying but with my lack of electoral knowledge it makes it harder haha. I would imagine the HR would have an existing relay for the fuel pump but as i have wired in this relay for the factory computer, i no have wires that i don't know what to do with! As you can see I'm not up to speed with electoral work atm .

[Don Dada]

Yea.. the better thing to do is wire over fresh, but the fact remains if the neg trigger out from the pfc is remaining on constantly there will be nothing you can do otherwise, hence my suggestion to test pin 18 first of all and then go from there

[Dose Pipe Sutututu]

where are you located? doesn't say in your signature.. if you're in Sydney or nearby I could wire it up for you for a small fee or a nice slab of beer

[Ad's]

Im locted in SA so is a fair hike unless you wanna fly over? haha

Hopefully be able to look at it early next week and ill see how i go!