Integrated Oil Pressure Switch and Sender?

[240260280]

@Captain Obvious & @zKars

 

Just checking with you to confirm that the 87 Fiero has a combination oil pressure switch and sender?  I wish to continue to use my oil pressure gauge and have a cut off switch for an electric fuel pump.

 

https://www.rockauto.com/en/catalog/pontiac,1987,fiero,2.5l+151cid+l4,1249141,electrical-switch+&+relay,oil+pressure+sender+/+switch,4588

Thanks

[Captain Obvious]

Yes, both sender analog, and an on-off for the fuel pump. I didn't look anything up in any manuals, but anecdotal data says the switch should close over 4 psi.

Here's a page with some info about the sender units. Note that 87 and earlier is different than 88, but I think it's mechanical differences only. Electrical they are the same 84-88.
http://web.archive.org/web/20151002182213/http://home.comcast.net/~fierocave/oilsender.htm

[240260280]

Thanks CO!

[Captain Obvious]

My pleasure.

Did you verify that the plumbing connection taper threads are the same? Most, if not all, of the plumbing on the Z is BSP, while the Fiero should be NPT.

If you're just looking to jamb it in there once and have it not leak, you'll probably be OK with some schmutz and/or Teflon tape, but if you're a purist, you might not like mixing the threads.

[SteveJ]

What about STANDARD MOTOR PRODUCTS PS173? Supposedly, it's designed for a 1978 280Z. If I don't miss my guess, the vertical connector on the T is the one for the negative pin for your fuel pump relay. I have one in my parts stash just in case I ever want to convert to an internally regulated alternator on my 260Z.

Edited June 29, 2018 by SteveJ

[Zed Head]

There's this one also.  Correct threads too, I assume.  How'd you get off to Fiero land?

https://www.rockauto.com/en/catalog/nissan,1978,280z,2.8l+l6,1209260,engine,oil+level+sensor,5700

[240260280]

Thanks guys!  Don't disrespect Fiero's on threads that CO is on ?

[Captain Obvious]

LOL. I don't think there was any disrespect. Here's my translation:

"You know that for the 78 280Z, Datsun went to a three prong oil pressure sender that has a switch built in. And those switches are still available aftermarket for cheap.

So with that in mind, why are you messing around with adapting Fiero parts (which may or may not have the correct plumbing thread) when you could just buy the sender unit for a 78 that already has the switch AND has the correct threads?"

I believe that's what SteveJ and ZedHead are alluding to.

[240260280]

Just ordered one with some other stuff for blue. Thanks all.

[Jeff Berk]

I've got a '74 260z and I just realized that the electric fuel pump was not functioning, just the mechanical. I'm not getting power to the pump and have yet to test the pump by applying power directly to it.  The double relay system in the car from the factory that uses the engine speed to kill the fuel pump seems like a complicated setup. Would I be better off switching to a combination oil pressure/fuel cutoff switch? It seems more straight forward and would offer protection if I lost oil pressure. My son wants me to install a fuel pump switch on the dash, but I think he likes the idea of having to flip switches. 

Jeff

[SteveJ]

I'm not sure why you think it's complicated. The electric fuel pump has 3 switches. The first is the ignition switch. The second is a normally open contact on a relay. That relay coil is energized when the alternator is turning fast enough. (Note the voltage for that coil comes from the yellow wire between the alternator and voltage regulator. If you swap to an internally regulated alternator, you will remove the coil voltage from this circuit, and the fuel pump will never get voltage.) The last switch is a normally closed contact on a relay that opens up when you are cranking the engine.

Diagnostics go like this:

1. Turn the key to the ON position.
2. Use a voltmeter or test light to verify you have voltage (to ground) on the black/white wire on Relay 1. (It's the 4 pin connector.) If this test fails, find the break in the wire.
3. Start the car.
4. Use a voltmeter or test light to verify you have voltage (to ground) on the green/white wire on Relay 1. If this test fails, you need to replace Relay 1. (This will require substituting a modern relay.)
5. Use a voltmeter or test light to verify you have voltage (to ground) on the green/white wire on Relay 2. (It's the 6 pin connector.) If this test fails, find the break in the wire.
6. Use a voltmeter or test light to verify you have voltage (to ground) on the black/white wire on Relay 2.  If this test fails, you need to replace Relay 2. (This will require substituting a modern relay.)

[Jeff Berk]

Thanks for the detailed diagnostic decision tree.