Dual station electric oil pressure gauges read low and other issues

[sdowney717]

I notice when I turn the key to on, the oil gauges move up to read maybe 10 lbs? Without the engine running.
I have mechanical gauges and they read normal, about 10 to 15 lbs higher
I checked the sender ohms, and it reads 120 ohms with engines off, so they are dual station senders.
I swapped in a new gauge and it responds like the old gauge.

Do your oil pressure gauges move when you turn on the ignition switch?

I will check the senders and wires out some more.

 

[alldodge]

I notice when I turn the key to on, the oil gauges move up to read maybe 10 lbs? Without the engine running.
I have mechanical gauges and they read normal, about 10 to 15 lbs higher
I checked the sender ohms, and it reads 120 ohms with engines off, so they are dual station senders.
I swapped in a new gauge and it responds like the old gauge.

Do your oil pressure gauges move when you turn on the ignition switch?

I will check the senders and wires out some more.

I would say yes, that is as a non-expert but with some knowledge.

Dual station senders (120 ohms) are half the ohms as a single station senders (240 ohms). Turning power on to the gauge causes the gauge to start reading. The resistance being half the ohms cause the meter to react. If your not having problems with the differences between the mechanical and electrical gauges when the engine is running, I don't think there is a problem

 

[sdowney717]

I would say yes, that is as a non-expert but with some knowledge.

Dual station senders (120 ohms) are half the ohms as a single station senders (240 ohms). Turning power on to the gauge causes the gauge to start reading. The resistance being half the ohms cause the meter to react. If your not having problems with the differences between the mechanical and electrical gauges when the engine is running, I don't think there is a problem

These are SW gauges. I replaced with another gauge, and it reacts the same.
On the SW gauges, turn on the ignition and needles move to the first white mark, which seems to to be 10.
I think they should stay down at zero with ignition on and engine off.

But I am having problems with the electric gauges, they read too low compared to the mechanical gauges.
I have lived with this for a while, maybe as long as I have had the boat. It is one reason I added mechanical gauges as I dont trust the electric gauges accuracy.
I figure either the senders are bad, they are likely 20 years old, or the wiring is weak. I did renew-clean and verify the terminals. The gauges are fine as the new replacement gauge reacts like the other three. I had to replace it since a prior owner put in a non marine version of an SW oil gauge and it completely rusted away.
I put in a Teleflex in it's place.