JE Oil pressure switch - WHY ?

[izu069]

it does with the oil pressure light

So you agree - like I say, the fuel pump cuts out several (tens of) seconds after the engine stalls?

For aftermarket mods, racing etc, it's supposed to cut out when the engine stalls - not when oil pressure drops.

PS - FYI: I too have about 70 seconds cold. That's earthed switches, currently 2 in parallel, but previously tried others - all typical 3-5psi thresholds (G161-OHV; 2-W-50 GTX2 etc). Typical is 15 secs; or 10 secs on hot days. Gauge confirms pressure hold up. Not that any of that should be relevant!

[Holden202T]

For aftermarket mods, racing etc, it's supposed to cut out when the engine stalls - not when oil pressure drops.

If its so unsafe this way why is it what the speedway boys all run ?

[izu069]

If its so unsafe this way why is it what the speedway boys all run ?

Are you saying that because they run it, it is safe?

Or are you saying it is safe to keep the fuel pump running whilst there is still oil pressure?

Or that cutting the fuel pump upon loss if oil will better protect the engine (than an ignition kill)?


I don't know why speedway lads etc all(sic) run it. (I suspect why the industry allows it to continue...)
Maybe speedway lads their oil pressure will drop fast enough to be safe.
Or that any extra time running on a dry engine won't do any extra harm.
I can't explain why some - despite being warned of this - continued to run similar systems until their engines seized.
It's probably like most things - people keep doing whatever until they wise up.

I do know those that understand this issue have ceased both practices - ie, using oil to control fuel, and using fuel to kill engines.
Ironically, by not using oil pressure to control the fuel pump has saved them money and hassle - no need to fit 2-wire pressure switches - they just use the charging system that every vehicle has (and most racers), or air-flap switches, else (reluctantly) ignition sensors if no other (backup) is available.


But don't confuse the issue with what others do, or what has been done.
If I did that, I too would still be using oil pressure, rotating tyres, and attacking evolutionists.

Try to think of it from the POV of my comments - the two different intentions etc.
Comments like "the oil pressure switch in commodore/camira etc are wired up as a backup for the fuel pump relay meaning if the relay fails the fuel pumps will still run to get you home!" repeats what is known and probably just confuses the issue - although it does agree with my original comment that the Camira fuel pump will continue even if oil pressure drops to zero - it doesn't enlighten with some forgotten or missed detail.

Trust me, when it clicks, it becomes so obvious. Unless there is something I and others have missed....?

[Holden202T]

if you are so dead set against using the oil pressure then talk to them, i'm not saying its right or wrong thats simply what i've seen from my mates speedway car and what hes told me .....

i agree if doable a alternator is probably the best way to kill the fuel pump as it is instantanious but as i mentioned before i tried your wiring diagram on my commodore alternator and i could not get it to work no matter how i did it (ie. with relay or transistor to power relay etc) so in my opinion its probably still a good way to do it, its just never going to happen in my car.

As far as the oil pressure being unsafe .... no i don't think it is .... if the alternative is nothing to kill the fuel pumps then i'd pick the oil pressure everytime and i stand by my statement that it HAS TO HELP if only a bit for lessening engine damage in EFI applications ..... yeah sure you might loose oil pressure and damage pistons or whatever but its going to be better than torching an entire motor.

and if the engine stalls in a crash then either

a. the fuel lines arn't ruptured and hense theres no problems.... or
b. if they are then the residual pressure in them is going to pump out enough fuel to cause a decent issue anyways ....

either way i really couldn't be fucked arguing about this anymore cause i just don't care!

[izu069]

I forgot it was you that has the charge light problem, but that sounds like a faulty regulator - those VNs use the same regs I used.

As to the rest, I can't convince you obviously - it's like convincing people that kinking oil lines doesn't increase fuel pressure (to the bearings), or that the oil pump does not determine oil pressure etc.

Or there is nothing to convince or argue - you have different priorities to others.

I don't give a crap if people damage their cars. We all love the Darwin Awards. The industry thrives on situations like this. And whilst I often save people effort, time or money - and even create new markets - the industry seems to dislike these evolutions....


The FPR issue for me was initially how it was the wrong way to protect an engine.

Later when applied to competition regulations, it also became one of safety.


If others have got any reasons that have been overlooked, I'm interested in hearing them.

But for me it's not an argument. If is fait accompli.
Certainly I haven't seen any new arguments presented herein.

And my initial post was to highlight what the Camira wiring DOES NOT DO. I wasn't intending to repeat stuff from elsewhere.


To think this issue is easy! (But so too is CAS-less sequential.)
Wait till you get into isolation & kill switches (not that anyone will provide a detailed appraisal or priority of what they are protecting against).

[DELCODE]

What a load of shit.Whatever your on you need to halve the dose.

[delcowizzid]

theres allways one on every forum just took us 160 members to find one. i see some thread cleaning coming

[djbrooksy]

come on guys lets just agree to disagree

i can see all points made and can see the good and bad in all.
be it the safest way or not in standard form holden have done it as a part of the limp mode not fuel pump relay back up

holden 202 has done it his way cause for what ever reason could not get it to work
of the alternator and has a point with
the residual pressure in the fuel line is going to pump out enough fuel to cause a decent issue anyways ....


and izu69 was only trying to point out the fact in HIS eyes using oil pressure to control the fule pump
be it the way holden have done it or the way holden 202 has done it can lead to problems

that all said im not wanting to end up on anyone's s@#t list or add fuel to the fire here
but some thing i was just thinking about is
if using the switch to cut the fule pump with lose of oil pressure wouldn't that
cause a few lean strokes before pressure in the fuel line dropped off and you came to a stop

now everyone play nice or i will tell mum

[Holden202T]

well in my opinion if an engine is going lean because the fuel is cut from lack of oil pressure, the damage done from no oil pressure is most likely going to be more of an issue than a moment of leanness ....

either way both are issues i don't really want to have to come up against any time soon

[djbrooksy]

either way both are issues i don't really want to have to come up against any time soon

true that