[hiccup]

The electrical sender/analog gauge system is prone to false readings, especially as things age (like the wiring/connections). Step 1 is to get a reading with a fluid filled mechanical gauge. Temporarily remove the sender and replace it with a mechanical gauge and get readings in F/N/R. Get a gauge good for about 600psi, less than $20 on Amazon. Use a thread sealant. The connection for the sender is 1/8 NPT. Normal pressure in N is about 70psi.