Your friend the circuit opening relay (or how to wire fuel pumps)

[infotechplus]

Injected VK commodores and (I think) injected XF falcons used a tachometric relay for the fuel pump. Cheap from Pick n payless.

Excuse my ignorance but where on the Commodore or Falcon do you find these relays? In the normal black [junction] box?

I'm going up to P 'n' P this morning.

Cheers,

Peter

[sideshow]

in fuse box

but they might not work on toyotas as the rpm signal form ignitor is not strong

you might have to run the signal from the coils

think holden still make the relay new but they want 90 bucks for it

[BradW]

What he said ^^^^^.
They are like a normal relay but with 2 extra pins.

[cptsideways]

SUPERB!!!!

Spent the past few days (weeks) trying to wire up my 1JZ into my old GZ Soarer & am currently stuck tring to find the god damn COR on the Soarer, anyone know where the damn thing ACTUALLY is (I know its in the footwell) but its amongst 7 others & I can't identify it.

That or the wires in the yellow plug that connect to it would be handy!! I've got conflicting info here


Also the 1JZ has two FC outputs at the ECU & I'm not sure which one does what, I think there is an FP, FC & also a D1 thats seems to be on the same system, any ideas??

[DeftAnesthetik]

kinda off topic a little but still about fuel pumps and relays...... i am putting in two pumps, one as a low pressure, high flow sucktion to pull fuel from the tank and feed it to the high pressure efi pump, should each pump be on its own relay or can i just use the same feed from the COR to power up both pumps?

[ViPeR_NiPPleX]

depends on how much current they draw and the rating of the COR.

[DeftAnesthetik]

duh, I should have known that. funny how you forget the obvious some times. thanks anyway.

[Bahnugget]

how would you go about running a COR on carbs? (without using a tachometric relay)

[Hen]

Bah - Check the link to Timbo's solution at the bottom of the first post.

[Hen]

Just had another idea about setting up a COR for carby fed cars.

Using this circuit:


I think it should work. Just tune the resistors and gain of the transistor (can't be arsed myself right now, and it depends on things like the oil pressure light). Only issue I see is that you'd have to hold the key in start until you got oil pressure, which might be a few seconds after startup.

Hen

[brett_celicacoupe]

only problem with that is that the oil pressure light is on when there is no pressure. no pressure usually occurs when the engine is off (...usually)

thats just for an idiot light type though

[Hen]

Brett, that's exactly right.

No oil pressure = oil pressure switch closed (earthed) = transistor not operating = no current through relay coil = no fuel pump.

Oil pressure = switch open = transistor operating = ... = fuel pump

Hen

PS - And yes, if you have a gauge, things will be harder, though you **may** be able to tune thigns to work anyway.

[Billzilla]

Done it three ways so far on my cars -
- Oil pressure switch. This is on the Sprinter, with the factory Altezza management.
- Tachometric relay things. Again on the Sprinter when it had the 4AGE and I needed all the outputs from the Motec. It was a VK V8 fuel pump relay I think.
- The Motec output. You just tell the Motec that it's a fuel put relay and how long you want it to run for with then engine off, anywhere from 0 to 20 seconds I think.

[brett_celicacoupe]

something RPM triggered would be best but im not sure how youd go tapping off the points or igniter without disturbing the waveform.

the voltage spikes might kill the components after a short while

[TooF]

has anyone gone wiring in an interia switch in with their fuel ciricut ?

alot of new cars tend to have these in there so in the event of a crash it will automatically cut off fuel supply. im about to put a new ecu into mine and obviously this will result in a bit of rewiring and was thinking of going down this path.