Dynon Fuel Pressure Sensors

I'm posting this to alert any other Dynon customers that may be experiencing the same fuel pressure problems I've been dealing with for a few months. This is, in no way, intended as a criticism of Dynon. I'm merely trying to raise awareness of this issue.

I had unreliable fuel pressure. I replaced the legacy Dynon fuel pressure sensor with a Kavlico 0-15 PSI sensor that I bought from ACS in August of 2015. My fuel pressure indications were better but I still had issues. I'll save you the details but, the big reveal is in why they were unreliable.

It turns out the 0-15 PSI sensor that I received from ACS was actually a 0-150 PSI sensor. I didn't discover this until I sent the numbers stamped on the sensor to Dynon tech support. So, all my reliability issues were actually due to the fact I was trying to operate the sensor in the lower 10% of it's range. Obviously not good. Dynon tells me that they had a packaging problem with some of these sensors and sent out some 0-150 sensors in 0-15 packaging. So, it wasn't Spruce's fault, they thought they were delivering the 0-15 sensor I ordered but I actually got a 0-150 sensor.

The bottom line here is that you should check the numbers inscribed on your fuel pressure sensor to ensure you have the right sensor installed. For a carbureated engine like mine, you need the 0-15 sensor. You can find all the numbers on the Dynon website but, if you have any questions, give Dynon tech support a call with the numbers off the sensor in hand.

To their great credit, when this issue revealed itself, Dynon was happy to send me a new 0-15 sensor for free.

Thanks again Dynon for the great customer service!

I think I helped Dynon discover his problem. A lot of head scratching, but Mike in tech support knows his stuff, so when I called and read him the number stamped, he knew right away which was which and where the problem was. Great people to deal with.

I just went through this, I took out all the parts for my EMS install and lied out the sensors on the table, the oil and fuel PSI senders look identical, had to look up the numbers on the Dynon site, I have a 0-50 for fuel and 0-150 for oil, easy to mix these two up.

I have several of the Kavlico sensors and was at first quite concerned about the wide range stamped, when I was going to use only a little at the bottom. Dynon assured me that these sensors have accuracy over the entire range. Did changing from the 0-150 to the 0-15 cure your problem?

DonFromTX said:

I have several of the Kavlico sensors and was at first quite concerned about the wide range stamped, when I was going to use only a little at the bottom. Dynon assured me that these sensors have accuracy over the entire range. Did changing from the 0-150 to the 0-15 cure your problem?

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Unless you are dealing with very high end stuff, I would not expect quality resolution at the extremes of the measuring range. I see pressures around 3-4 PSI (at altitude) in my carb'ed setup and I wouldn't expect any 0-150 PSI sensor to provide reliable reporting in my range and that seems to be proven with the OP's experience.

Larry

The issue with the OP is that while the system thought they had a 0-15 PSI sensor, they actually had a 0-150. The system didn't know what sensor they had, so when the 150 PSI sensor saw 5 PSI, it changed the output 3% instead of 33%. So SkyView would show 0.16 PSI, not 5. This isn't an error in the sensor, it's that the system assumed a different sensor, making the error look huge.

The sensors aren't more or less accurate or sensitive at the top or bottom of their range. The issue is total percent error. They are spec'd at 2% error, so a 150 PSI sensor can have up to 3 PSI error. Fine when you are measuring 100 PSI, not so good when you are measuring 4 PSI. It doesn't matter if you are measuring 4 PSI, 75 PSI, or 146 PSI, the error band is the same.

That's why we sell 15, 50, 75, and 150 PSI sensors. The 2% error does make it so that it makes sense to choose the right range, but it's not like you need a sensor rated for 33 PSI to read 30 PSI.

Most importantly, make sure SkyView is set to the same range as the actual sensor or nothing will make sense.

Fuel Pressure Sensor

Kudos again to Dynon Tech Support (Mike) for helping me figure this one out. I haven't received the replacement 0-15 sensor yet. The behavior that Dynon described in the previous post is EXACTLY what I was seeing though so I completely expect to see a vast improvement with the 0-15 sensor.

Low Fuel Pressure Fixed!

I installed the 0-15 Kavlico sensor today and test flew it for an hour. It works perfectly. For the first time since replacing the legacy Dynon fuel pressure sensor, I have solid, reliable fuel pressure readings. It was unfortunate that Dynon packaged a 0-150 sensor as a 0-15 sensor. I spent months chasing the problem. But, once I zeroed in on the issue an began collaborating with Dynon Tech Support, they went over and above helping me resolve the problem. They even overnighted the new sensor to me.

I hope this thread will help some future searcher avoid a similar experience. Check the stamped numbers on those sensors before you install them folks!
Randy

dynonsupport said:

The issue with the OP is that while the system thought they had a 0-15 PSI sensor, they actually had a 0-150. The system didn't know what sensor they had, so when the 150 PSI sensor saw 5 PSI, it changed the output 3% instead of 33%. So SkyView would show 0.16 PSI, not 5. This isn't an error in the sensor, it's that the system assumed a different sensor, making the error look huge.

The sensors aren't more or less accurate or sensitive at the top or bottom of their range. The issue is total percent error. They are spec'd at 2% error, so a 150 PSI sensor can have up to 3 PSI error. Fine when you are measuring 100 PSI, not so good when you are measuring 4 PSI. It doesn't matter if you are measuring 4 PSI, 75 PSI, or 146 PSI, the error band is the same.

That's why we sell 15, 50, 75, and 150 PSI sensors. The 2% error does make it so that it makes sense to choose the right range, but it's not like you need a sensor rated for 33 PSI to read 30 PSI.

Most importantly, make sure SkyView is set to the same range as the actual sensor or nothing will make sense.

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Is it possible to post the stamped part numbers of each fuel and oil pressure sensor on here so we all can check what we have?

Thanks!
BK

Bottom line, its the installers responsibility to verify the part number of every item put on an aircraft, that's why they are marked on the part during manufacture.

From the Dynon Manual:

Fluid Pressure 0-5 PSI (Kavlico) – P/N 101715-000
Fluid Pressure 0-15 PSI (Kavlico) – P/N 101690-000
Fluid pressure 0-50 PSI (Kavlico) – P/N 101716-000
Fluid Pressure 0-150 PSI (Kavlico) – P/N 101693-000
Fuel Level (resistive)
Fluid Temperature 1/8”-27 NPT (Dynon Avionics) – P/N 100409-000)
Fluid Temperature 5/8”-18 NPT (Dynon Avionics) – P/N 100409-001
OAT (Dynon Avionics 2-wire) – P/N 100433-003