911 ST dash switches

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911flyboy
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911 ST dash switches

Post by 911flyboy »

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I am looking at installing a switch for my fog lights and have found the correct switch but have always wondered what these two switches do here. Nearly every ST ( rep and genuine) seem to have them and I feel I’m missing out!
I’m sure somebody can tell me what they are for but I’m guessing it’s a dual fuel pump thing?

Thanks

Rich


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Lightweight_911
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Re: 911 ST dash switches

Post by Lightweight_911 »

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They're for individually isolating the 2 x CDI ignition units on twin-plug engines to facilitate trouble shooting ...

.
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mrg3.6
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Re: 911 ST dash switches

Post by mrg3.6 »

Strangely after years of pontification, I've just received a new wiring loom from Jan at http://www.raceservice4u.com in Belgium to finally connect my two dash switches to a pair of 8 pin CDI boxes.

Now I just need to sort out a fog light switch :)

Martin
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911flyboy
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Re: 911 ST dash switches

Post by 911flyboy »

Well there you go. Live and learn. Would they have had a switch for changing over fuel pumps in the cockpit too?
Thanks for the info,

Rich
stretch
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Re: 911 ST dash switches

Post by stretch »

No. The pumps would both be running. Piggybacking each other.
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mrg3.6
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Re: 911 ST dash switches

Post by mrg3.6 »

Any wiring diagrams for both the twin CDI switches and the twin fuel pumps would be graciously received?

Thx
Martin
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911flyboy
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Re: 911 ST dash switches

Post by 911flyboy »

Ok thanks. That’s a lot of fuel going in then!
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Re: 911 ST dash switches

Post by BILLY BEAN »

911flyboy wrote:Ok thanks. That’s a lot of fuel going in then!
Not really. The pumps are located above the tank so don't get any benefit from gravity. ( regular one pump installations are located low down from the fuel tank) Both pumps feed into one small fuel pipe which has a finite fuel flow capacity. Additionally, the fuel console has a regulatory influence on fuel flow. Any unused fuel not utilised by the MFI pump
(presumably the same principle in carb application) returns to the fuel tank.
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