mazda rx-7 fuel pump

[kmack]

This was also discussed a few years back, but I think on the email list...

Some Ford cars and trucks run an impact cut-off switch. Particularly, Ford Escorts and Ranger pick ups, are the ones I know for sure. If the vehicle was ever in an accident, the impact would trigger the switch closed and cut power to the fuel pump. The fuel pump would not get power until the reset button on the switch was pushed.

Escorts had the switch located in the rear usually behind the rear quarter interior panels (Left side I believe). The Ranger pick ups had them mounted under the dash (center) right about where the carpet terminated at the bottom of the dash board.

Simple to install really, you just wire it in before the fuel pump and place it in a place where it can be accessed if you ever hit anything. Which hopefully, will never happen.

As for the oil pressure switch, I can see one benefit. If you ever lose oil pressure while driving, either because you burned all the oil up and never checked it or the oil change service place forgot to put the drain plug in tight, then theorectically, the engine will die and keep you from going any further without oil.

[ricksaia]

Great replys. The Ford inertia switch sound good. I may use it. Rick.

[ChrisA]

Hey Rick, you asked about using a relay? I use one of the little black square Bocsh relays on my car. The fuel pump uses some seroius current and as we all know the stock wiring is fragile enough. I have an aftermarket relay/fuse panel up high on the right kick panel. It powers the fuel pump, aftermarket radio and amps. Its a Painless Wiring thingy I got from Jegs. Its got the relay and three fuses for the individual circuits. I mounted it up high enough so you cant see it unless your looking for it.

I'm still checking on the pressure switch cut out. Looks like it ties in with the starter solenoid and the ignition switch for getting the car running then will kill the pump if the oil pressure goes below 4 pounds. Mr Gasket and Holley each make a version, I dont know which one to get yet. Besides the plumbing issue I'm still thinking about.

Chris

[ricksaia]

I have a 1970 and the wires are by the tank for the electric fuel pump. I am not getting any power to the positive side, even with the key on. I will work on this. This will make installation a bit better. Rick.

[Bambikiller240]

My understanding is that the wires are there, but not connected to anything (either pump on one end , or power on the other end). You'll need to fish around under the center of the dash for the other end of those wires and connect them to a power source.

[260Zed]

I wired mine so as when the alternator circuit drops out (When engine stops) it cuts the circuit to the fuel pump. Should work fine as long as when i crash, the engine stops!

I also mounted it in the engine bay so it pulls the fuel. Haven't had any probs with it mounted this way, although if my 75 had the wiring to the rear, I prolly would have put it there.

Good luck

Luke

[Bruskiz]

The parts you need for this can be ordered from McMaster-Carr

Adapter

Male 1/8" NPT to Female 1/8" BSPT for connecting existing oil pressure sender to Tee #4092K26 $5.24

Hex Nipple

Male 1/8" NPT to Male 1/8" BSPT for connecting Tee to engine block where oil pressure sender was before. #4092K81 $3.87

SS Female 1/8" NPT Tee, where everything comes together, adapter, hex nipple, and oil pressure safety switch. #4443K641 $8.30

With this setup you don't need to tap out the existing threads on the block and you don't need to replace your current oil pressure sender. If you want to switch to a different oil pressure sender you already have NPT threads for it.

I have a GP Sorensen oil pressure switch I picked up at Advanced Auto Parts, sorry don't have the part number, but it looks to be the same one as Summit Racing Oil Pressure Switch

Here is a link to the Holley website that has a diagram on how to hook up the wiring.

I haven't actually wired the oil pressure switch or installed my pump yet, but hopefully this helps you out.

Later,

Mike

[Bambikiller240]

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[Bambikiller240]

This is great information, Mike. Thanks for posting it! Information like this gets me (and others) much further down the road on this type of project. Thanks for taking the time to put it all together and post it.:classic:

I noticed that Holley doesn't show a relay in the circuit to power the Fuel pump, does anyone know how to modify the circuit shown in the schematic to incorporate a relay to protect our fragile 30 year old wiring?

[ChrisA]

Originally posted by Bambikiller240

......relay in the circuit to power the Fuel pump, does anyone know how to modify the circuit shown in the schematic to incorporate a relay to protect our fragile 30 year old wiring?

How about this?

Chris

[ricksaia]

Thank you everyone. This is going to be such a cool car. Rick.

[Zedrally]

Well I'm at a loss as to HOW you all expect to "prime" the fuel bowls when the pump will not function unless the motor is running?

Possibly, a by pass circuit the powers up the fuel pump when the motor isn't running?

Forget the fancy options and just go with the pump with the in-built safety.