Hey guys,

As usual, you folks are absolutely amazing about responding with thorough and thoughtful responses.

I have this question though, I don't know if I'm being too **** about my vehicle but I think there may either be something wrong with my oil pressure gauge/sensor or oil pump...

The reason why I'm saying this is that when the car starts up cold, the oil pressure is REALLY irratic, it will go up to 50%, down to 0% then to 15% 20% and so on until eventually it kind of stabilizes in park at about 15-20% I also notice the needle is very shaky instead of smooth.

Then after I leave my garage, and start to drive, if I hit about 2,000rpms the needle starts to drop to 0 violently and stay that way for a bit (a few seconds) and then go back up to 15-20% as if it was nothing.

And then once I hit the freeway, going 65mph to 70mph my needle reads about 20% and in 10 minutes after the car has been riding a while, it levels off at a nice, even 50% and stays that way.

So I dont know if its the oil pump acting wacky, or the sensor or gauge, or is the normal? I have no idea. Is there any way that I can check externally (without digging into the engine) to test if its a sensor acting weird/gauge or pump?

Any suggestions would be great guys, thanks a ton!

 

Year of your car and model is most important, however in most cases it's the sending unit on the engine on z car from 1970 on. Bet that's the culprit.

 

Oops! My mistake! It's a 1983 Datsun 280zx

Sending unit? What's that? I'm still learning how the car functions inside and out.

 

Moved to S130 / 280ZX forum.

RETICON, click:

XenonS130 - S130 Reference
Nissan OEM part diagrams
Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

 

Thanks for switching to the right forums. Been sick, hard to focus.
I already have the reference and diagram sheets all printed and in a binder too. Did it when I purchased the car.

 

Likely the sender unit... but you would have to check.

 

What are some techniques to check and diagnose this issue?

 

XenonS130 for the FSM. Probably run meter leads inside the car and see if the resistance jumps all over the place when you are driving. Mine did the same thing and when I pulled the connector off it was covered in oil. Cleaned it out and it was fine until enough oil got in there to cause a problem again. My sender had a very slow leak - replaced it and it's been fine.

 

I looked at the FSM and saw that there is an oil pressure switch. I haven't worked on the engine yet, if that oil pressure switch is dirty, could that be a culprit? Or is there a sensor elsewhere other than that switch?

I attached an image from the 1983 FSM with the engine assembly the object in question is highlighted in red. I'm just wanting to know if the switch contributes to the oil pressure meter in the car or is it a sensor elsewhere?

 

there is a sensor for the oil pressure. if you ground that wire to the frame it should pin the gage to the max. bad connection corroded can cause weird readings but just get a new one they are cheap and be sure the connection is clean and corrosion free. what you have highlighted is it. called a switch but isn't a switch.

 

Actually depending on what year you have there is an oil pressure switch. Check out page EF-21 in the 1980 FSM and you'll see where the oil pressure switch hooks up to the fuel pump relay.

 

says he has an 83

 

Right so his wouldn't be an "oil switch".

The reason I mentioned it is because people come and search for answers to their questions - not just the OP. When they come to this thread they will see the extra information that broadens the thread not to just cover the 1983 model but all 280ZX from 1979 to 1983. Most people don't even know that the oil presure switch interfaces to the fuel pump relay or even that some cars have a second fuel pump relay for that matter. Now they do