OleKnees

Hello All –
I’m a new owner of a 1993 Rx7 and I have a newbie problem and question to ask. (and will have more in the future) The car is in good shape and runs well, however, over the weekend I drove the car and noticed the oil pressure gauge jumping up and down quite a bit. At one point, the needle went down to zero. My immediate panic was calmed as I seemed to remember reading threads over the years about this gauge and how it’s struggled to work properly for many owners. Instead of shutting the car off I decided to cautiously drive home. When I got back I inspected the car and everything appears fine.


Anyways to the point. I’ve read several threads regarding the oil pressure gauge, and while there seems to be opposing opinions on the actual need of the gauge in the first place, I’d like to explore fixing the gauge onmy car so that it is working properly. (or as properly as it can) With that said, it seems like most people replace the oil pressure sender in order to correct the problem. My question is, how do you determine this is the actual cause of the problem? In other words, is there a way to test the sender itself? Or are people simply assuming this is the problem based on others experiences? I’d like to fully understand the problem before buying & replacing parts.

Thanks for any guidance you want to provide, and my apologies if I missed an obvious answer or location for this info.

Cheers,
Chris

Sgtblue

iTrader: (16)

AFAIK real oil pressure issues are rare. Most problems with indicated oil pressure are due to either poor contact of the spade connection at the sender or a bad sender. Clean that connector with a bit of sandpaper or cleaner and make sure it's tight. If indicated pressure, especially at warm idle doesn't improve it's probably the sender itself.

FWIW I think the Service manual specifies minimum oil pressure of 55 psi @ 3000 rpm.

OleKnees

So more of a "process of elimination" approach. I'll give it a try this weekend and report back if I get stuck. Thanks for the advice.


Cheers
Chris

Sgtblue

iTrader: (16)

You could check the FSM but I don't think there's a way to bench test the sender. And last I checked they're over $100 for new. That's why I suggest checking that connection first. It's location under the filter pedestal means it can get dirty over time. The weaker signal at idle may not be getting thru and showing as zero pressure that suddenly jumps with higher rpm (stronger signal).

j9fd3s

iTrader: (3)

basically if you want to diagnose the gauge, you can look up the values for the sender in the manual, and then you put resistors or some kind of potentiometer between the gauge and ground. then you can turn the key on (engine off) and watch the gauge.

if it works, you need a sender (or engine), if it doesn't work, you need a gauge or the wire