I have an 86 BRAT GL EA81 car and I have rebuilt the the oil pump and purchased a new oil press sending unit. Prior to the rebuild my oil pressure gauge would stay pegged out. After the change, The needle barely moves up at all and doesn't even reach the numbers so i suspect the new sending unit to be faulty. 

 

After installing the pump i noticed i have a pressure switch for a dummy light as well as a sending unit for pressure reading but i only have one wire. Where is the wire i am supposed to connect to the pressure switch? 

Of the ones I have seen, (others I am sure will chime in shortly) it is one or the other. Even the few later models with a gauge and light, only had one sender, and the light was ran off of the gauge.

Fastest toubleshoot is to simply re-install the original unit, and see if the gauge reacts.

If it does not, I would move to checking for proper ground, and weather the sending unit is using the correct resistance. (Found by either testing, or simply googling the unit numbers to check listed application)

Edited November 14, 20178 yr by charles_thomas

1. It doesn't have it. Your engine isn't original and came from a car with a dummy light. Simple as that. 

 

2. Get the sending unit from Subaru. Aftermarket are crap, don't work, and may dump all your oil out on the ground. If that happens see #1.

 

GD

Edited November 14, 20178 yr by GeneralDisorder

Thanks everyone! Trying to track down a part number for a factory sending unit. I'll let y'all know what happens.

I read somewhere in here ? Someone said run one or the other but not both gauge and idiot light and of course the usual internet way - not explain why

 

I run both idiot light and saas gauge and sender with no troubles. The gauge is just more variable info to fill head with as I drive

How did you run both wires?

Factory wire to idiot light and had to put my auto elec cap on to wire up the gauge and its sender. The sender has a screw terminal for earth as well.

 

Do you not know how?

Aha. I missed the part about the aftermarket gauge.

Aha. My gauge runs low when my twin rad fans come on. Only just wired them both with relay each and power from battery. Maybe I need to earth gauge sender direct to batt neg!