Yeah, that's how they work. It takes a pretty good thump to trigger it, though - there's no way a bumpy road would do it. If it's mounted vertically, with the button facing up, it needs a longitudinal impact to trigger it (such as a side, front, or rear impact). It's designed that way on purpose, and vertical thumps (such as a large bump while driving) don't trigger it. I've tried, whacking it with a screwdriver handle. Smack it as hard as you like from the top or bottom, and nothing happens.
I was a professional crash investigator, analyst, and reconstructionist for about 15 years, as well as attending non-serious crashes, traffic tie-ups, etc. I've seen many (I'd estimate between 50-100) of these switches triggered, and in every single case, it was a situation when you'd
want it to have triggered. I was often a "hero" when I could get a Ford to fire right up after a crash (serious enough to have been dangerous, but not enough to leave the car completely undriveable) by disappearing into the car for a moment, pushing the button, and saying "There. NOW try it!"
In the event that you install one of these, and find yourself miles from nowhere with a failed switch, simply joining the two wires together (bypassing the switch) will return normal fuel flow. I've heard rumors that it's possible for one of these switches to fail, but never actually found a first-hand report. When you play with one of them, it's hard to imagine any way to get one to fail.
Perhaps spilling a latte with cream & sugar into it might be able to gum it up
but, failing that, they seem pretty much a foolproof design.
The connector has 3 wires. The skinny one is not used, and has no connection inside the switch assembly. I simply cut off the 3rd, skinny wire, and wired the other two across my fuel pump power wire. I've tried it, giving it smacks from various angles to simulate a crash, and it works great.
It's certainly better than getting in a crash & having the pump continue to pour fuel out everywhere.
Cheap, cheap, cheap insurance, IMHO.
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