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MG TD TF 1500 - Inertia Fuel Pump Switch

A while back I purchased an inertia fuel pump switch from Moss, and am finally getting around to installing it (along with a supplemental fuel pump). But I got to wondering... which is usually dangerous. How effective are these things on our cars, given that there is quite a bit of fuel in the SU bowls. Wouldn't the engine keep running-on even if the inertia switch killed the power to the pump? For how long? Any prevailing wisdom on these things?

Safety? Fast?
Scott Ashworth - '54 TF
S. R. Ashworth

Scott - The purpose of the inertia switch is to keep fuel from being pumped out of a broke fuel line, possibly fueling a potential fire in the event of a wreck - it has nothing to do with shutting the engine down. Cheers - Dave
David DuBois

Scott,

These switches are useful for fuel injected engines, where cutting the fuel cuts the engine.
If you want to use the switch to cut off the engine and the fuel line on your TD/TF you can use a double pole relay.

John
J Scragg

Dave and John,
In our usual effort to over-complicate the very simple, we were going to combine the inertia switch with a solenoid that would shut off all power in the event of a crash - as John suggests. That appears to require a special solenoid designed to operate in an always-on mode rather than a $10 universal unit from PEP Boys. Instead of over-elegantizing this project ($$$), I think we'll just install the switch we have to protect from a broken line, as Dave mentions.
Thanks for your thoughts,

Safety? Fast?
Scott Ashworth - '54 TF
S. R. Ashworth

Scott - "I think we'll just install the switch we have to protect from a broken line"
That is all it is in the MGB. If you put the inertia switch in line with the white circuit, it will cut power to the ignition and the pump (both are on the same circuit). The added advantage to that, is if the switch shuts off on its own from time to time (something that MGB drivers complain about), you wouldn't have the situation where the fuel pump is shut off but not the ignition, making it very obvious that the inertia switch needs to be reset. Cheers - Dave
David DuBois

I had a late MGB with an inertia switch. It would shut off if I went too fast up the ramp entering a gas station or for other unknown reasons. I bypassed this PITA after 3 false alarms.
Safety Fast!
Chuck
cj schmit

This thread was discussed on 04/04/2013

MG TD TF 1500 index

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