BRAVA 1.6SX N reg

I bumped the small box under the passenger seat when vacuuming and the car would not start. Eventually AA guy came and even he had difficulty until he noticed that the car was clean and it immediately dawned on him what the problem was. There is rubber like membrane on top (not exactly a button) which he pressed and the car started. Seemingly this is a common problem with the Brava and it has been known for this to be bumped when driving with subsequent cut out of engine.

Couldn't find anything in manual about this and cannot remember what he called it. Wasn't fuel filter - I think he referred to it as the fuel cut off switch?

In any event since then I have started engine and depressed membrane/button to see if it would cut out engine and have also deliberatley bumped it again whilst cleaning to see if this would do anything. Engine did not cut out in either cases.

Reason is that I may have an injector problem (light on). At present trying the redex/higher quality fuel approach and next stage is ohmic test (probably next week when I get new meter). The problem has only started and I did let the fuel run to practically tank empty recently so think it may be gunk rather than injectors. Looking ahead at other possible reasons (if injectors are eliminated) what does the box under the seat actually do.

its as you said a fuel cutoff, its designed to trip in the event of a crash.

i too tried to make mine trip just for a laugh without luck but it worked fine in a crash

It is, as you suggested, a fuel cut off switch also known as an inertia switch.

It's designed to cut off the fuel supply in the event of an accident to prevent fuel spilling over the road if a fuel pipe fractured. On some cars it also unlocks the doors in the event of an accident.

Dave.

yup sounds like the interia/fuel switch. Designed to cut fuel pump in event of an accident, and even if the ignition switch is turned off then on again, or relay is reset, it still won't let the car start/issue fuel until the button is pressed.

Didn't know about the door thing!

alot of later cars dont have them, fuel cut off switch is built into the airbag module (ECU)

Mine had a weird problem recently - was driving along, and the car just stopped working, lost all power, steering, abs, everything.

Turns out the cut off switch tripped while i was driving, had to get a new one put in.

I used to do roadside breakdowns on Met. police cars in London. The inertia switch would often trip while they were chasing someone as they went over a speed bump. Very embarassing to watch the baddie get away just because of this switch so they used to tape them down. Illegal because they were disabling a safety feature, so whenever the cars went into one of the Met. garages at Euston or Wapping they would have to take the tape off. It was a never ending cycle of tape on - tape off - tape on ........

The inertia type switches can also trip sometimes just by bumping a wall or bumping off a kerb. Some Ford cars that had them fitted in the boot would trip if you threw something in the boot (punctured wheel for example), we used to get lots of breakdown calls from people saying "I've just changed a wheel and now the car won't start" , so it's a good idea to know where yours is if you have one. Beats waiting for the AA or RAC to turn up just to press the button for you.

Dave.