Thoughts on fuel inertia switch?

[Neil]

Don't need one for mechanical fuel pumps. Not sure why you wouldn't spend $30 to lessen the probability of a fiery death.
You do you.
But ask your next 5 passengers if they would prefer that the car they are riding in keeps pumping fuel in the event of an accident, or would prefer a $30 device that would *almost* definitely cut off the fuel flow during such an event.

Sometimes oil pressure sensing switches are used in industrial applications to protect engines. I suppose it would work in a car, too if the engine stopped. If so, the switch could shut off an electrical fuel pump.

 

[Jean-Marc]

Neil, you are right, but it would be necessary to make add relays to allow to start the pumps when the engine is not running yet, at this time oil pressure is zero

 

[Douglas]

Neil, you are right, but it would be necessary to make add relays to allow to start the pumps when the engine is not running yet, at this time oil pressure is zero

I am actually doing this on my build, since I am utilizing a drysump setup, (incase I lose the belt somehow) I decided to use a low oil pressure switch that will control through a normally closed relay, the pressure switch will be controlled through a single pole switch next to the fuel pump switch as an arming circuit. This way I can still start the engine then arm the LOP circuit to kill the fuel pump relays in case of oil pressure loss. I determined the $60 for the extra work is worth the rest of the investment.

Also running an inertia switch as well to kill the pumps.

 

[Frank Catt]

Why so complicated ? The whole thing can be done for just a few parts and low cost. Instant fuel pressure dump instantly any of the external or ignition switches are turned off, very simple and very effective.

 

[Douglas]

Why so complicated ? The whole thing can be done for just a few parts and low cost. Instant fuel pressure dump instantly any of the external or ignition switches are turned off, very simple and very effective.

It isnt complicated, it is a simple circuit with two forms of protection one from oil loss and the other impact.

Everything in the system has automatic protection for $60 all relays, switches and sensors.

 

[Brian Kissel]

Frank. Can you please put up a detailed post of what you use so others can determine if that is something they would like to include in their build.

Thank You !!!
Regards Brian

 

[Frank Catt]

Sorry Doug, the system I am showing is to prevent engine fires from pressurised fuel in the engine bay, particularly relevant to carburettor cars, I have seen too many fires whilst the driver is in the car, particularly on start ups.

 

[Neil]

Neil, you are right, but it would be necessary to make add relays to allow to start the pumps when the engine is not running yet, at this time oil pressure is zero

A time delay relay would allow the engine to start and build up oil pressure.

 

[Neil]

Sorry Doug, the system I am showing is to prevent engine fires from pressurised fuel in the engine bay, particularly relevant to carburettor cars, I have seen too many fires whilst the driver is in the car, particularly on start ups.

As I found out in my Porsche 911, in a rear or mid-engine car the driver is the last to know the car is on fire.

 

[Richard Milner]

I also strongly recommend a fuel pressure dump valve if running carbs.

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I also strongly recommend a fuel pressure dump valve if running carbs.

Back in the 60s racing P1001 we would plonk a metal picnic tray on the Weber’s to avoid the chance of a fire.
The fuel pressure dump system you fitted to my GT40 works a treat Frank. Now - ignition off, fuel pressure dumped. Battery master to off. Peace of mind.
It also solves another annoyance. After a fast run filling with fuel meant spending 20 minutes or so before the hot engine would re-start. No problem now.