Printable Version of Topic

Posted by: kconway Oct 5 2011, 07:18 PM

I'm installing a fuel pump and want to wire it from the fuse board under the dash. I'm going to isolate the pump with a relay so the pump only runs with the key in the "on" postion. I believe I need switched and unswitched power to the relay. Can anyone tell me what terminals and/or fuses on my 74 fuse block would work? I don't have a battery to test for switched power or I would do so.

If I'm off base in my thinking, please let me know.

Kev

Posted by: swl Oct 5 2011, 07:50 PM

There was a thread not long ago that discussed a way of using the oil pressure sensor and relays to ensure the pump shut off if the motor failed (crash scenario).

Let me look...

There it is - http://www.914world.com/bbs2/index.php?showtopic=143464

This approach was done in the engine bay but Valy's cct could be located anywhere.

Posted by: SLITS Oct 5 2011, 07:55 PM

Mr Gasket (Mallory) made an oil pressure switch. I don't remember how it was wired.

Posted by: 76-914 Oct 5 2011, 08:43 PM

Autolite, too. IIRC 10-30lb & 30-60 ranges were available + others.

Posted by: kconway Oct 5 2011, 10:22 PM

Can I just jumper a wire from my oil pressure sender connection on my pressure gauge in the dash to terminal 86 of my relay?

Kev

Posted by: Valy Oct 6 2011, 12:19 AM

Yes, its the same wire.
The yellow wire comes from the ignition switch. I don't like cutting wires, especially high current ones so I suggest you connect to it under the passenger seat at the seat-belt relay.
For the switched power you can use the read/white that feeds the wipers and blower motor in the front or any of the full red wires that feed one of the red fuses (8,10 or 12).
And please add a fuse inline with the wire that goes to the fuel pump.

Have fun!

Posted by: SLITS Oct 6 2011, 07:01 AM

I do remember that there are three connections on the switch. One was power to the pump. Of the other two, one was normally closed and it may have come from the starter solenoid wire for startup and the other was normally open where power would come from a switched source when the switch proofed and closed with oil pressure.

I think the oil pressure sender is a variable rheostat/thermocouple (grounding) and I don't think you can tie a line into it to power the pump.

Posted by: jaxdream Oct 6 2011, 09:42 AM

No experience with the idle oil pressure of a -6 , but the -4 has a low idle pressure ( varys from engine to engine )when warm , especially stock unmodified engines . Chosing a switch that will cut off the fuel pump should be concidered with this in mind. Just a thought fellas...

Jack

Posted by: Valy Oct 6 2011, 10:35 AM

The original fuel pump runs off the relay board not the switch. It is controlled by the FI brain and always switched-off when the engine stops. It's G6, the rightmost element in the diagram with the black/red wire.

The oil pressure switch is F1, in the middle of the diagram, green/red wire, grounded at point 70.
As the name says, it's a switch not a rheostat.
Further up, K3 is the low oil pressure light.

Posted by: andys Oct 6 2011, 10:40 AM

Though I can see the benefit of an oil pressure energized fuel pump relay, the "crash senario" doesn't mean the motor stops running (to shut down the fuel pump). With that concern (on my EFI V8 car with 58psi), I'm adding in a Ford inertia switch which shuts down the fuel pump relay from an impact or roll-over. One nice feature it has, is a normally open contact that you can wire to illuminate a light to warn you when the switch has been tripped (should someone bump your car while in a parking lot). Find a solid chassis mounting for it, and splice it into the fuel pump signal wire and you're done. The Ford inertia switch is available from Summit, as is the pigtail connector.

Andys

Posted by: SLITS Oct 6 2011, 05:41 PM

Kevin is running a 2.4L /6 engine. While there is a possibility of using the idiot lite sender, his oil pressure sender will not function in the mode he is speaking of.

Posted by: kg6dxn Oct 6 2011, 06:18 PM

Here is a good refernce book to have.

 Relay_Book.pdf ( 1.08mb ) Number of downloads: 223

Posted by: Prospectfarms Oct 7 2011, 12:59 AM

That's useful. Thanks a lot!

Posted by: jaxdream Oct 7 2011, 09:10 AM

Yep , thanks , although I'm about as electical as a kitchen match...

Jack