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Facet fuel pump wiring
AL20vT - 15/2/08 at 06:01 PM

Quick question regarding wiring a Facet fuel pump:
The Facet manual recommends powering the pump via an oil pressure switch.
My pinto has a single terminal pressure switch at the moment, can i simply run a power cable from the fuse box to the fuel pump via this pressure switch?



Whilst on the subject, can the current single oil pressure switch also supply my oil pressure gauge, or do i need something else?

Cheers,
AL

Macbeast - 15/2/08 at 06:14 PM

I cannot imagine why they want to run the petrol pump via the oil pressure switch.

With your single-terminal pressure switch lower right, that terminal will be connected to earth (chassis negative) until pressure builds up so if you feed 12V to it a fuse will blow (hopefully).

If you want to run an oil pressure gauge I think the answer is to buy a T adaptor so that you can take one arm of the T to the gauge and screw the existing switch (which controls the red oil warning light) into the other arm.

Ermmmm-

One other thing to check- is the red circled terminal lower right actually the oil pressure switch or the temperature sender? I dont have my manual to hand.

Somebody will tell us in a moment



[Edited on 15/2/08 by Macbeast]

AL20vT - 15/2/08 at 06:17 PM

Manual says the oil pressure safety switch will stop the pump operating if the engine stops and the ignition switch is on......

indykid - 15/2/08 at 06:18 PM

how do you start it then?

do you need a priming switch to fill the float chambers while the oil pressure builds, or just crank til you get the pressure and then the pump starts?

i don't think many other people do it this way and i you'd need to use a relay either way.

tom

Paul (Notts) - 15/2/08 at 06:19 PM

Dont bother. Just run the power straight to the pump. The Idea is that you use a special oil pressure switch that cuts the power if oil pressure is lost, thus saving your engine. The switch on the engine you have works the other way round., and is just for the warning light on the dash.

I just used the feed in my loom straight to the pump. ( I also put an ineria cut off sensor in this feed )

Paul

ps. ignore the spelling mistakes.

[Edited on 15/2/08 by Paul (Notts)]

britishtrident - 17/2/08 at 10:00 AM

Just fit a "bump switch" as on fuel injected cars.

02GF74 - 17/2/08 at 09:28 PM

quote:
Originally posted by Macbeast
I cannot imagine why they want to run the petrol pump via the oil pressure switch.



I am puzzled too.

12 V - lamp - O.P.S. -- 0V

circuit as above.
when ther is no oil pressure switch is closed so circuit is complete.

If you wire between lamp and OPS then power is off to pump when engine runs = no good. Plus resistance of lamp will limit power to pump.

Anywhere other point would not really involve the OPS.

Now using the outpput from alternator that goes to charge lamp makes sense - thiswill power pump only if alternater (aslo engine) is running but you need seom override when cranking the engine.

David Jenkins - 17/2/08 at 10:37 PM

If you use one of those oil pressure switches then you have to provide a bypass switch so that you can start. It's not rocket science - you just put a relay in the starter solenoid circuit so that when you turn the key to 'start' the relay closes and shorts out the oil pressure switch. When the engine starts and the oil pressure is up you return the key to the 'run' position and the system is set.

I believe that this is the way that Caterhams are set up - there's certainly someone on ebay selling oil pressure switches labelled as 'caterham style'.

I chose to fit an inertia switch.