Fuel Pump Cut Off Switch

tom_sprecher

tom_sprecher

Super Moderator
Can anyone recommend a 1/8" NPT oil pressure operated fuel pump cut off switch? Something with 3 terminals (one that grounds and two that open at low pressure) would be ideal.

I want something that will cut power to the Facet pump used on the 1st gen should the engine stall or pressure drops below maybe 20#. Had a BBQ under the back of my car when a fuel line was sheared last time I wrecked and forgot to bring hot dogs. Want to avoid it the next time I do something stupid (or keep a package of brats in the cool helmet cooler just in case). :D
 
You're better off just getting a cheap oil pressure switch, such as is used for low pressure warning lights. Most likely this will be a NC ("normally closed") switch that 'opens' when pressure rises above a certain point. Use this switch to "pull closed" a SPDT relay and use the NC contacts ("normally closed") contacts of the relay to power the fuel pump. Sounds a little complicated, but it's not.

Most 'low pressure switches' aren't that robust, and might not handle the current needed for a fuel pump.

Where can you find an appropriate relay like I described above ? Easy. Find a German car in a junk yard (VW, BMW, Merc), root around under the hood or under the dash. You'll find a treasure-trove of Bosch relays, that almost always have the circuit diagram printed on the side of the 'can'. Most of these can handle high currents, and you can connect to them with 'push-on' crimp wire lugs from any auto parts or hardware store.

To complete the system, you'll just need a momentary switch to 'override' the relay when you want to start the car, as you won't have any oil pressure then (duh).
 
Geeze, why make it so complicated John, all he needs is a mechanical pump run off the cam. Wink wink, nudge nudge.
 
Geeze, why make it so complicated John, all he needs is a mechanical pump run off the cam. Wink wink, nudge nudge.
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Since the GCR says it's an approved mod I have already removed the above mentioned pump as it proved too unreliable.

A nod's as good as a wink to a blind bat! :D
 
I like the $14.79 thingy from Pegasus...didn't know anybody was making one for that direct application.

Yeah, Mark. Got a couple of cars with those cam or crank-powered fuel pumps...never had one fail due to electrical problems, EVER !!!
 
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