Pressure sensor stopped working

[maartenversteeg]

I have a legacy Dynon fuel pressure sensor (100411-000) and I installed it in my project, initially it worked fine, gave a zero pressure reading on the display (in my garage) but recently it stopped working (red cross). I tried to reinstall old configuration files but that didn't help. When I measure the sensor I get a resistance of 5.4 ohm, when connected to the Dynon I see a raw value of 99 with a CalV of 0.1196 and an indication of nan for the pressure measurement. Is this a proper behavior for the sensor or is something broken?

 

[maartenversteeg]

Add: Pressure sensor stopped working

The temperature in my garage has dropped, could it be that due to a change in the sensor temperature the resistance of the sensor changed and that the converted value now falls outside the valid range?

 

[jakej]

Maarten

Did you try connecting a ground wire from the sensor to the Dynon ?

Jake J

 

[maartenversteeg]

Jake,

There is one ground wire connected to the sensor (from pin 30) and the fuel pressure sense wire (from pin 8) at the 37-pin connector that normally goes into the EMS I measured the 5.4 ohm between these two pins, this is the configuration that indicated a zero pressure before. Would you mean that I need to connect another ground wire to the sensor? The sensor itself is isolated from frame is connecting to rubber fuel hoses and is supported by an adel clamp.

 

[jakej]

Maarten

Yes, you must have the sensor grounded preferably to a ground direct from the Dynon.

Jake J

 

[maartenversteeg]

Jake,

Yesterday evening I finally got around to testing the fuel pressure sensor again. Adding a ground from Dynon to the fuel pressure sensor didn't change anything (partly as expected since there are already two wires between the EMS and the pressure sensor: pin 8 the sense signal and pin 30 ground, each goes to one of the two tabs on the sensor). Then I realized it is much colder in my garage now than it used to be, so with my heatgun (on low and pretty far away) I heated the sensor slightly.  This did the trick, the raw measured value from the sensor increased from 117 to 140 and with this the converted value came within range and the Dynon reported a zero pressure again. So I think this is a combination of a zero fuel pressure on the sensor (no wings with tanks attached yet) and the temperature sensitivity of the sensor just pushing the converted output value below the lowest allowable pressure of zero and thus indicating that the sensor was broken (red cross).