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Pump inertia switch
iiyama - 1/6/08 at 10:15 AM

As topic, I havent fitted one. Should I? If so where in the circuit would it go?

David Jenkins - 1/6/08 at 10:21 AM

It's a good idea to fit one - not nice to have a crash that leaves you senseless for a while, with the fuel pump whirring merrily away, perhaps spraying fuel round the engine bay...

I got one off ebay for around £6, ex-Rover I think.

Easy to wire up - it has 2 wires, and they're normally connected together. Just wire this into the electric pump circuit, so that if the switch is triggered the power to the pump is cut.

In my installation it was easy to include the car's ignition circuit, so that both the pump and the engine are stopped - but I designed my car loom, so I knew where to put the switch!

HTH
David

iiyama - 1/6/08 at 01:46 PM

So as I have a bike engine I could wire it in to the engine stop switch? That would kill pretty much everything in the car. well except for me of course!

David Jenkins - 1/6/08 at 02:06 PM

I'm not sure how the stop switches work - do they disconnect something, or make a connection? If they disconnect then it would be easy to put an inertia switch in series. Not sure how you fit one in if the kill switch is a 'make' switch.

matt_claydon - 1/6/08 at 02:23 PM

On my SV650 the cut-out switch is wired so the contacts must be closed for the engine to run. If yours is the same, which it probably is, then it would be fine to put the inertia switch in its place.

iiyama - 1/6/08 at 03:36 PM

Yup, break the circuit to stop the engine.


Cool. Thanks guys.

One last question though, do these inertia switches have to be mounted in a particular direction? And if so is this marked on the case?

David Jenkins - 1/6/08 at 04:28 PM

This is the one I've got


EBAY LINK

It's got a rubber 'button' at one end, which goes upwards - the connector goes on the bottom. Mine's screwed to the driver's side of the bulkhead.

iiyama - 1/6/08 at 04:51 PM

Thats the one I was looking at.

Cheers peeps!

How do these work then? Hopefully vicious braking and acceleration dosent activate them?!

[Edited on 1/6/08 by iiyama]

C10CoryM - 2/6/08 at 12:40 AM

quote:
Originally posted by iiyama
How do these work then? Hopefully vicious braking and acceleration dosent activate them?!


Braking can if they are sensitive or are mounted at the wrong angle. Typically they are just a ball sitting in a tapered hole. Hard enough hit and it slides up the taper and trips, opening the electrical circuit.
The idea is to have them on your electric fuel pump so if the lines rupture in a crash it doesnt keep pumping fuel. Shutting the engine off w/o killing the fuel pump defeats the purpose.

iiyama - 2/6/08 at 06:21 AM

Fully understand the reasoning for fitting one bud, which is why I am interested in putting one in the car. Seems like a damn good idea!

However my car is track orientated so maybe its not such a good thing to fit? After SVA I will be fitting an FIA cut off switch but an automatic switch might buy a few seconds if the unthinkable happens........ If its going to activate everytime I decelerate for Lavant or Woodcote though it aint gonna be much cop!

dhutch - 2/9/09 at 01:22 AM

Presumably they are resetable?

Looking at geting one of these, which seem to be cheapest of most, all of which appear to look the same.


Daniel

britishtrident - 5/9/09 at 07:38 AM

quote:
Originally posted by dhutch
Presumably they are resetable?

Looking at geting one of these, which seem to be cheapest of most, all of which appear to look the same.


Daniel


Just push the rubber button to reset the "Bump Switch" --- on any car you drive you should always know where it is located as they very occasionally trip out for no obvious reason.