oil pressure switch

[cogcaviz24]

so my fuel pump stayed on and killed my battery. i searched the fiero tips site found the post on the oil pressure switch keeping the fuel pump on, tested mine and it tested bad. my question is,  which part do i need to get? autozone has 3 different parts. a $5 part with one connector, a $6 part with 2 connecters, and an assembly for $35.

[Fierofool]

The prices you quote don't sound right for an oil pressure switch.  The oil pressure switch is a round device about 2 inches in diameter and about 4 inches high.  It has 3 male terminals sticking up out of the top.  It generally costs around $50.  You want to get the one for the 85-86 2.8 because there is some differences in the internal circuitry between those and the later 2 years.

It sounds more like you're talking about the fuel pump relay, one of 2 relays located behind the air filter canister.  The other is the AC relay.  To test them, you can swap them out and if the other system doesn't work, you know it's the relay.   

[cogcaviz24]

the $35 part is the entire switch, the other parts appears to be an internal part of the switch.                  www.autozone.com/autozone/parts/1986-Pontiac-Fiero/Oil-Pressure-Switch/_/N-ijd5mZ8znc6?filterByKeyWord=oil+pressure+switch&fromString=search

[Fierofool]

The oil pressure switch for the 2.8 is a sealed unit and isn't serviceable.  The PS228 is the correct switch. 

[cogcaviz24]

i ordered a PS223 this morning, should be there now. ps228 is a part for a different engine.

fyi, the low dollar parts are for cars with a oil LIGHT while the high one is for cars with a gauge.

my empty wallet kept me from seeing the functional differences

[Fierofool]

I'm not sure the other two would even plug up to the Fiero harness.  The one you got also has a circuit in it for the oil light, which is built into the auxiliary gauge pod.  The Fieros that have the oil gauge in the instrument cluster have an oil light in the 2 rows of warning lights in the center of the instrument cluster.  Sorry for the PS228 typo. 

While you're in there, it'd be a good idea to attach a mechanical oil gauge and let the engine warm up to operating temp to see what your true oil pressure at idle speed.  Many of the new sending units give an incorrect reading.  I once bought 3 before I got an accurate one.  Autozone and Advance were both incorrect.  I got a good one from AC Delco.  Ed Parks at The Fiero Factory received a whole batch that had a faulty circuit in them.  He was the one that alerted many of us to the problem.  If you need to borrow a mechanical gauge, I have one. 

[cogcaviz24]

Its installed! what a pain in the butt. i borrowed a mechanical oil pressure gauge from my neighbor. the read out on my gauge isn't perfect, but its close.

[Fierofool]

I hope you removed the battery to get access to the sensor.  A 9/16 open end and a small adjustable wrench makes it pretty easy.  Or should I say easier?  It's even easier on a notchback because you don't have to work over the long sailpanel. 

[cogcaviz24]

yeah,i took the battery out. i didnt have a 9\16 for some reason. vice grips did the trick. i climbed in the trunk and hugged the engine. i changed out the belts too, also not that fun in the driveway