Hi guys,

I've put an electric fuel pump in '78 F150.

I'd like to have some kind of shut off switch for the pump to be activated in case of an accident.

What are the different types of switches? Where should I get one?

NAPA had some kind of oil-pressure based switch, but I don't want to lose my guage, and they were clueless as to it's operation.

-maharashii

 

Why not go to the junkyard, cut the connector off of a truck there, and get the switch for that truck from Napa or Ford. Just wire the switch into your pump circuit, most of them were just two wires, and have have fun. If you off-road a lot though, I wouldn't put the switch in- any hard hit would turn off the fuel, and you could get massively stuck.

 

sounds like you're describing an inertia switch. What donor vehicles would I look for? I don't do a lot of hardcore off-roading, but I'd rather not cripple my truck.

the napa switch was an oil pressure switch. if the engine is not turning, the oil pressure is low and the switch cuts off the pump.

disadvantage - lose my mechanical oil pressure guage? I assume it has a sending unit that goes in the same spot as my pressure guage.

I've seen a fuel safety switch described as "a must for all trucks with aftermarket electric pumps" in parts catalogs ($50) but no description as to how it operates.

 

You don't want an oil pressure switch like you described - when you're trying to start, you'd have to wait for the engine to spin SEVERAL times for pressure to build up, or it would NEVER turn the fuel pump on. And if the starter didn't turn fast enough (bad starter or low battery), it wouldn't come on either.

You need an inertia switch, which does exactly what you want, and they're easy to find in junkyards. I put one in mine when I swapped in a '95 engine.

http://www.superford.org/registry/ve...661&original=1

 

good advice - thanks

What would be a good donor vehicle for the switch? Where do I find it and how do I get it off?

 

Any fuel injected vehicle has one. But some diesels don't. So, look for '88-current fuel injected truck. The switch is often behind the brake pedal and clutch pedal(if applicable) on the firewall. It should have 2-4 screws and a plug. Cut the plug wires back about 4" from the plug(so that you have pigtails to hook to) and undo the screws. To back sure that the switch works, push the button down and continuity should be zero(as in power won't go through), and with the switch up, the power should go through the switch. Then wire the switch in line between the fuse and pump.

 

the inertia switch has a button? What does the button do in normal operation?

 

The button is what moves when the inertia switch is activated. It makes the switch open, in other words, it keeps the current from going through the switch. It is usually just alittle red button on top of the box.

 

This is a generic one. You can go to any parts house and get one as long as you can get the plug, you can use any brand.