poor oil pressure indication

[isnms]

My oil pressure indication sucks. An test gauge shows the, operating temp, idle, pressure, to be ~20psi. My gauge sits near to zero.
Would this most likely be the sending unit, wiring or the gauge?

 

[scottiedawg66]

Usually the gauge.

~scott

 

[smagnotta]

Hrmmm...

I always heard it is most likely the sending unit.

I guess check all the items you listed...

By the way, my does the same thing - I just check the level of oil to make sure it is OK and ignore that gauge.

 

[scottiedawg66]

You can check the sender with an OHM meter. So all you really need to do is that to determine what you need to replace. In the 3 MKiiis I have experience with that have no oil pressure readings it has been the gauge. Mabyee just me tho.

~scott

 

[isnms]

I checked every page on the lubrication section of the tsrm and did not find out how to test the sending unit with an ohm meter.
Could you tell me where it is?

 

[scottiedawg66]

I dont believe there is one on TSRM. I just checked for continuity, then used my alligator clips on my ohm meter and reved to 3000rpm to see a voltage, or change in impedence, cant remember if that gauge reads off resitance, or volts, i think its a voltage change.

~scott

 

[Bishop92t]

I have seen a couple Supras where the oil pressure sending unit was at fault. They're fairly cheap from JW, just hard to replace. IMO the real fault is the whole system is 1980's technology and you'll never get a good oil pressure reading off the stock gauge. A nice aftermarket unit is my solution.

 

[scottiedawg66]

same here bish autometer or bust.

~scott

 

[chevyeater]

My stock guage reads 35 psi @ hot idle so, it is possible for it to work (it is correct as well).

The easiest test for the guage and wiring is to remove the plug from the sender, turn the key on and check the guage, it should be all the way up. Then, ground the wire and check the guage again, it should be all the way down. If it works like this, replace the sender. If it doesn't work like this, either the guage or wire needs repair.

 

[isnms]

^now that's info I can use.
Thank you chevyeater

 

[chevyeater]

You are welcome. Only one little correction, I realized that I remebered backwards, lol! After consulting the TSRM to be sure, wire off should be guage down, wire grounded should be guage up. Sorry!

 

[CPT Furious]

Yes, when grounded it shoots all the way to the top. My wire accidentally broke and I watched the gauge peg in about 2 seconds! Needless to say I freaked until I opened the hood and saw the wire laying on the block...

 

[isnms]

How fast is the gauge suppose to react?

I tested my gauge. When grounded, the needle would go all the way to the top. When I removed the ground it would very slowly fall back to zero. Hit it with ground again and it would go all the way to the top. It wasn't instantaneous but it was quick. Remove ground and slowly it would travel back to zero.

 

[chevyeater]

It is working then, they are filled with molasses.

 

[isnms]

That's good news.
I did not get the sending unit replaced today. The one I got from autozone had the wrong thread pitch or just the wrong part. When I took it back they double checked and it was the one they showed to go on this car. :dunno:
Unless someone has a known good working unit for sale cheap :icon_ques I'll just order one from Champion Monday.