Intermittent oil pressure reading

[Ketchgould]

I have all new wiring, sensor and gauge on my 1961 graymarine seascout for oil pressure. My gauge only either reds 40psi or zero. I've tested the new gauge, it's fine.

My sensor would not fit directly on the engine due to the tight spot so I ran poly hosing about 18inches to the sensor. The sensor is still grounded with a terminal end on the threads where this wire then grounds to engine negative bus bar.

You can see the oil retract down the poly line when the engine is not in use. I've bleaded the line of air, oil still retracts down.

What's wrong?

Poly a bad idea?

Should I get nipples and fittings to make awkward hard connection of sensor to engine?

Old gauge ran oil mechanically through gauge and several feet of oil pressure lines.

Thanks
Christian


Christian Gould
St. Paul, MN
S/V Sea Dog
Apostle Islands Lake Superior