JE Oil pressure switch - WHY ?

[Rock_Lobster]

Hello the DELCO collective,

Looking at the JE Camira setup, why is the oil pressure switch wired in parallel to the fuel pump relay ?
The manual states that the fuel pump relay turns on initially, then on again once the ecu sees the engine cranking.
The fuel pump relay then stays on while the engine runs. The manual says the oil pressure switch is a backup.
Is the fuel pump relay that unreliable ?
Does anyone use it on a fresh install ?
Seems a waste of time to me.

Wayne

[delcowizzid]

yeah just a backup for the time it does happen.its not totally nessacary as you could allways hardwire the pump with a piece of wire if needed if it every stopped

[Holden202T]

or you could wire it the way i originally thought it worked and that is as a safety, so if you loose oil pressure it will kill the fuel pump ......

it does mean that theres two points of failure in that circuit, but it has its advantages ..... i'm using one of these switches in my gemini drag car to cut fuel pump in the event of an engine stall (ie. roll over or crash etc ...) and it has the added bonus of when theres no pressure it pumps 12V up the purple wire which you can run to your dash light for oil pressure!

[UCMatt]

The oil pressure switch is actually for backup fuel mode when the ECU is dead and not controlling outputs. The analog backup fuel controller can't drive the fuel pump relay so it relies on oil pressure to enable the pump.
Cranking times will be longer in this mode while oil pressure builds.
The O.P. switch also offers some redundancy in the event of a relay failure.

[Rock_Lobster]

So, there is an analog backup fuel controller ( limp home mode ) ?
Ahhh, now it makes some sense. Cranking will bring up enough oil pressure to run the fuel pump.
The EST module will handle the spark, and the analog will handle fuel, so at least you can get home.
MEGASQUIRT could not do that.

Wayne

[Holden202T]

BUT ... this probably wont work in a 202 ......

[UCMatt]

Yeah, the analog calibration for a 202 would be pretty rough.

[Holden202T]

well a camira limp mode might run on it .... but the question would be how close is the fuel timing for it

just carry a spare ecm and chip works for me

[Rock_Lobster]

That's the thing I could not get over with the Megasquirt. It was all custom.
If I broke down somewhere due to a faulty ECM, I was stuffed.
With the DELCO, any Holden dealer or nearest wrecker will get me out of trouble.
And it has limp home mode.

As for the limp home mode, I suppose whatever has the closest injector size out of
the Camira or V6 to the VK EFI will run the 202 the best. The volumetric efficiency wouldn't be too different,
as they are both 2 valves/cylinder, though with much improved intake ports..

Wayne

[Holden202T]

yeah but its the crank angle thats the problem i think ... either way i think the camira limp home is closer to what you want for a 202!