Get 0 at idle goes up to 40ish at 5k rpm. I read somewhere that I can run a ground wire to the sensor cable and the gauge will go all the way up. Just want to find out if it’s the gauge or sensor. Motor has been running for 2 years so I don’t think I have 0psi oil pressure at idle.

 

my guess is the sensor not reading correctly. the gauge either works or it doesn't. and yes, grounding the wire will peg the needle to the high side.

 

I wouldn't reply on the factory gauge. It's a good indicator that there is pressure. I alway run an after market gauge from an oil pedestal block. Same goes for water temp.

 

Your oil pressure is probably fine; rotary engines don't run for long without oil pressure. Just replace the "mushroom" sender unit located under the oil filter pedestal. These get gummed up over time from crap circulating through your system and eventually don't read properly to the gauge. It's a simple spin-off, spin-on and tighten thing, with a single spade connector. You might also get lucky and find the spade terminal is just corroded and when you clean up the electrical connection, it starts reading correctly at the gauge.

Even the gauge is optimistic, as these engines run at low oil pressures compared to most other engines; my SE runs at 40-60psi at normal operating temps at cruising RPMs, and it has a slightly higher regulator than a 12a. The engine won't run more 20-30miles with no engine oil, and hence zero pressure - and overheating would be your first clue.