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Randy,
I had a similar problem with the oil pressure sensor after about 12 years of service. Climbing out IFR I get a low oil pressure light, pull power, point the nose at the nearest airport and declare an emergency. Once on terra firma I diagnose a bad sensor. I buy a new one (only $350) install it and 6 months later deja vu all over again. I replaced everything but the sensor believing it couldn't be the sensor. Guess what? Now I'm pissed, so I research to find that the sensors are actually common industrial products, the Honeywell Media Mate series rated to only 90 degrees C., 50 PSI for the fuel (MM050PG1HA) and 100 PSI for oil (MM100PG1HA). However these use the Hirshmann connectors which use Faston friction connectors (which BTW may be where your problem lives) and Fastons are CRAP^2.
I decided to use a higher quality sensor rated to 125 deg C and design an adapter for a proper bayonet mill spec connector. See the attached picture. The sensor I used was a Honeywell 19C100PG4K (oil) and you would use a 19C050PG4K for the fuel (available for ~$130 from Mouser or maybe DigiKey).
Having said all that, the first thing you want to check are the connections to the sensor. Be sure you are getting 5 volts to the terminals of the SENSOR, NOT just to the faston. There can (will) be corrosion between the faston and the spade. Same goes for the output. The differential signal across the output pins should be 1mV per PSI on the fuel and 1mV per 2 PSI on the oil sensor.
On request I'll send you the drawing for the machined aluminum adapter.
Merry Christmas!
Brent Regan
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