Ford inertia switch
I'll have the Roast Duck
Joined: Jul 2002
Posts: 9,622
Likes: 108
From: Northshore, MN
I suppose you could put one before the ignition coil?
Let me reevaulate my answer. The idea of a fuel shutoff is that with the pump in the tank on most, if not all EFI set-ups, the circuit is stopped when it triggers. The wiring to the pump has the FIS inline. One can remove the switch and link a wire inbetween the two connections to bypass the FIS (not recommended, but with a plow truck pounding snowbanks, it's one way to deal with it.). Also the FIS when interrupted tells the pump to stop (I'm repeating myself, lol). If you have a mechanical pump on the engine, then there really isn't a way to stop fuel flow. However, to kill the engine, one could put one inline of the ignition to the coil. No spark, no run. If you have a carb'd engine with an electric fuel pump, then yeah, you could put a FIS inline with the wires running to the elec. pump.
Let me reevaulate my answer. The idea of a fuel shutoff is that with the pump in the tank on most, if not all EFI set-ups, the circuit is stopped when it triggers. The wiring to the pump has the FIS inline. One can remove the switch and link a wire inbetween the two connections to bypass the FIS (not recommended, but with a plow truck pounding snowbanks, it's one way to deal with it.). Also the FIS when interrupted tells the pump to stop (I'm repeating myself, lol). If you have a mechanical pump on the engine, then there really isn't a way to stop fuel flow. However, to kill the engine, one could put one inline of the ignition to the coil. No spark, no run. If you have a carb'd engine with an electric fuel pump, then yeah, you could put a FIS inline with the wires running to the elec. pump.
Cargo Master
Joined: Sep 2004
Posts: 2,757
Likes: 138
From: Alberta Canada
Fuel switch
Just thinking out loud; the inertia switch shuts off fuel supply by stopping pump, because fuel is under higher pressures it will run momentarily after impact, but will limit fuel flow.
If it were encorporated so that if interrrupts coil circuit , would you then introduce the hazards of losing power steering and power brakes (if you have them?) immediately ?
Tom
If it were encorporated so that if interrrupts coil circuit , would you then introduce the hazards of losing power steering and power brakes (if you have them?) immediately ?
Tom
Elder User
Joined: Jan 2008
Posts: 658
Likes: 0
From: N.W. Mo.
The inertia switch when tripped shuts the vehicle down almost instantly.
There is almost no lag time between the pump shutting off and the fuel pressure dropping below the pressure necessary to make the engine run.
There is almost no lag time between the pump shutting off and the fuel pressure dropping below the pressure necessary to make the engine run.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
Or, is this something used to cut power to an electric fuel pump to stop gas flow in case of an accident where the fuel line gets cut (or opened somehow negating the shutoff effect of the carb float)?
Or Both?
I'm having a little problem figuring out what it is you are trying to do here, or trying to prevent, and what exactly this switch is going to do for you???
Brick Brain J!
Laughing Gas
Joined: Dec 2007
Posts: 792
Likes: 3
From: Sandy Run SC
My 48 F-1 with the 95 T-bird 4.6 EFI has the enertia switch from the T-bird installed to cut off the fuel pump in case of an accident that would keep fuel flowing. I would highly recommend installing one if you are using an electric fuel pump. I think it is more critical with fuel injection because of the pressure. We installed one on my son's drag racer for safety also.
Trending Topics
Elder User
Joined: Jan 2008
Posts: 658
Likes: 0
From: N.W. Mo.
The enertia switch used on Fords trips and breaks the circuit to the fuel pump. It has to be manually reset to resume operation.
It is possible that they are now using a different system but I am not aware of it.
It is possible that they are now using a different system but I am not aware of it.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
I'll have the Roast Duck
Joined: Jul 2002
Posts: 9,622
Likes: 108
From: Northshore, MN
I'm only familiar with the ones from the 80's as well.
Post Fiend
Joined: May 2008
Posts: 7,641
Likes: 21
From: Poway, Ca.
Then if your fuel pump is powered when you turn on the ignition switch, then why not connect it to a relay which shuts off your switched ignition power. That would kill both the power to the pump, and the ignition to prevent the engine from continuing to run on "Bowl Gas?" Like Ross suggested!
J!
Cargo Master
Joined: Aug 2004
Posts: 2,575
Likes: 36
From: Greenville, SC
Elder User
Joined: Jan 2008
Posts: 658
Likes: 0
From: N.W. Mo.
That looks exactly like the inertia switch used on almost every fuel injected Ford car and truck.
It will shut off the power to the pump which will prevent fuel flow from any broken lines during a crash.
If used with a carb it will not instantly shut down the engine but the real safety issue in a crash is usually preventing fuel flow from an electric pump from feeding or causing a fire.
It would be a good idea to have one and installation is very simple.
Just install it in line in the wire that powers the pump.
It will shut off the power to the pump which will prevent fuel flow from any broken lines during a crash.
If used with a carb it will not instantly shut down the engine but the real safety issue in a crash is usually preventing fuel flow from an electric pump from feeding or causing a fire.
It would be a good idea to have one and installation is very simple.
Just install it in line in the wire that powers the pump.
Thread Starter
|
Fleet Mechanic
Joined: Sep 2002
Posts: 1,622
Likes: 3
From: okla
Thanks for all the input. I took Walstons advice and ordered the Ron Francis piece. Yes ,I know that I could spend some time and do it cheaper, but this does it quick, and his stuff is good quality. Thanks Walston, I had seen this before and forgotten about it. Joe
Fleet Mechanic
Joined: Mar 2005
Posts: 1,511
Likes: 1
From: peyton, colorado
52 F3, you're right. Shutting off the fuel pump in an accident is to keep the pump from dumping fuel on the ground. A carbed engine without fuel will quickly die if it didn't stall in the accident. I would advise you to place the switch where you can reach it easily, in the unlikely event of it tripping while driving. I've only seen one of these trip once, (dumb move by the driver) but he had to reset it in the trunk while dodging traffic.