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MG MGB Technical - Inertia switch

I have a 77 ex Californian roadster which has had the usual engine and carb modifications to bring it into the performance characteristics of an earlier UK car. I noticed a switch on the passenger side bulkhead which was not connected up and which is marked Inetia switch. I assume this is some kind of fuel cut off device? Can anyone advise. For what it's worth I removed it.
roger lawson

Your assumption is correct. It was supposed to cut off the fuel in the event of a collision. Unfortunately, they weren't too reliable and tended to capriciously cut off the fuel at in oppoortune moments. Most cars, including mine, have the valve bypassed or removed. I don't believe a replacement is even available.
R. L Carleen

Replacements are available- in fact, at least some of the early FI cars made in the US featured a similiar switch- A friend was unable to restart his taurus after an accidentdu to an inertail cutoff switch triggered
greg fast

FWIW: I have the original inertia cutoff switch still in my car and after 85k KM it has never given me any problems.
Dave Pearn

I installed a first inertia switch in the fuel pump circuit of my 74 roadster. I got it from a Ford Tempo in a salvage yard for $5. It's a quality item and was made in the UK. Most Fords have a similar switch but I don't know which cars in the UK would be the best source. I think all fuel injected cars have one but the Ford unit seems easier to find and it is a good switch. FWIW, Clifton
Clifton Gordon

This thread was discussed between 30/11/2004 and 01/12/2004

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.