15 replies to this topic

[mike.]

Tomorrow if all goes to plan, I will be removing my old 998 engine and preparing to drop in my new engine. I'm going to be running a facet fuel pump with the new engine and so will be needing an intertia switch. The facet instructions say to use an oil pressure switch, but I can't really understand that because it would be possible to crash the car and sever the fuel line, but still have the engine running for a minute or so on the fuel left in the lines and the float.

So i'm going to fit a proper inertia switch. I've just got a few questions.

I'm not going to buy a new one because they're about £25 from minispares, so i'm just going to get one of ebay from whatever car takes my fancy since they all do the same thing. Looking at all the photos of them, all the switches come with 3 wiring connections. I'm guessing these are 2 for the passing ignition live and one for an earth? Others only come with 2 which makes me wonder if i'm right about the third connection on some switches being an earth?

Also wheres the best place to mount it? It'll work anywhere won't it? Aslong as its bolted to a secure solid part of the car. I'm guessing the standard position on a mini is somewhere on the bulk head?

Thanks,

Mike.

[HARBER07]

Its double throw - ie. a common, normally closed or normally open contacts. You only need 2 of the connections. Sorry but can't remember what pins it is.

I mounted mine on the dash - easily reset.

[mike.]

Oh right i see. How can i test if i've got the right connections the right way? Would banging the panel the switch is bolted to be enough to trip the switch?

[HARBER07]

Multimeter set to Ohms, and test for continuity between the pins. Yeah just bash it against something solid - but don't break it . If you dont get a reply today i can check mine after work tomorrow. I dont have my car ATM.

[mike.]

Alrite then cheers. My dad will know how to do that, hes the electrical guru in or house.

I've found a switch on ebay off a range rover for a few quid, should do the job nicely.

[HARBER07]

Mine was off eBay for couple of quid also . Looks like Dan is gonna type something REAL big But nothing hard about it at all

[Dan]

Press the switch to make sure its closed and use a tester on it, which ever pins are closed are the ones you need. Give it a knock against something to trip it and test it again. The pins that were closed before should be open and the other terminal will be closed to whichever of them is common (usually the centre). This can be arranged to show a warning lamp when the switch has tripped if you like.

Secure it to the bulkhead. Mine is on a bracket that I made and fixed to the top of my brake servo crank box.

Looks like Dan is gonna type something REAL big

No I just got interrupted by the wife with a mission in the middle of posting.

[HARBER07]

[mike.]

Ok thanks guys. So once i've found which pins which, how do i wire it to a warning lamp? I'm abit of an novice when it comes to wiring but i'm guessing that once the switch is tripped, the third pin will then be carrying the current from the ignition live? So then i can just take a wire from the third pin to the terminal on the warning light, and another from the warning light to earth it?

[HARBER07]

Spot on mate Though i didn't bother with a light. You know when your pump has cut out - the car stops!!

[mike.]

Yeah but a friend of mine spent hours trying to start their car, checking/changing ignition parts etc before calling the AA out. The AA guy came, clicked the inertia switch and it started first time

At least if you have a light, you know for sure when its tripped and it'll ease the panic if you car does stop

[HARBER07]

True but the facet does make a bit of a racket - but mine isn't rubber mounted . Stick a light in - makes it look a little bit more trick

[Dan]

Yeah but a friend of mine spent hours trying to start their car, checking/changing ignition parts etc before calling the AA out. The AA guy came, clicked the inertia switch and it started first time

Exactly! You'd be amazed how many people do that.

[Sherlock]

Please excuse me for hi-jacking this thread, but while on this subject, does anyone know if it's a legal requirement to have an oil pressure or inertia switch on an electric /electronic fuel pump? The original Minis never had one.

[mike.]

Never heard of a law on it. Its probably an EU regulation on new cars though.

Its just a very good idea to fit one.