tomkk

tomkk

Well Known Member
OK, I seem to be plagued with fuel problems today. A sunk carb float and now no fuel pressure reading. When returning home yesterday, I suddenly started getting fuel pressure warnings and the fuel pressure gauge on my EMS display had a big red X across it. Some time later, the fuel pressure came alive but showed pretty wildly varying numbers. Then it went back to the big red X and that's where it is now. If I turn on the Master in the hanger, I get a steady red X.

This isn't a matter of an incorrect or inaccurate reading, Skyview apparently doesn't recognize the sensor or it's in a state that Skyview doesn't know what to do with.

I dumped the User Data from Skyview and Fuel Flow during the time when Fuel Pressure was wildly varying was normal but Fuel Pressure is mostly blank with some seemingly random bursts of pressure data varying from 0.1 to 14.9.

This is the three wire pressure sensor. I've checked the wiring and it seems secure.

My thought would be a failed fuel pressure sensor but I hate to just start replacing parts. Any suggestions? Anything I can check to make sure or isolate the problem?

Last, but not least, I don't see the fuel pressure sensor (p/n 101690-000) on Van's site. Any idea where I'd find one?
 
Contact Dynon

Might want to get the S/N off the back of the sensor and check with Dynon. There were a series of them recalled - was a posting on their website if I recall.

I had my first one replaced as it showed erratic values when changing altitudes. Unfortunately the new one is doing that from time to time as well - recent email from from Dynon tech to me questioned my grounding but I haven't checked into that yet. I would think yours has either completely failed or its indeed a wiring issue. As others on here will point out, it "usually" a loose connection.
 
A red X exists when the voltage SkyView gets is below 0.5V or above 4.5V, both of which are invalid. So a broken wire, shorted wire, or broken sensor.

The recall was for sensors that could read pressure wrong as you climbed. It was not for ones that failed and red X'd, so that's not the issue.

We sell sensors direct if needed.
 
dynonsupport said:
A red X exists when the voltage SkyView gets is below 0.5V or above 4.5V, both of which are invalid. So a broken wire, shorted wire, or broken sensor.

The recall was for sensors that could read pressure wrong as you climbed. It was not for ones that failed and red X'd, so that's not the issue.

We sell sensors direct if needed.
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Thanks. Is there a way I can check out the sensor. Is it a resistance that changes with pressure that I can check?
 
Mine just did the same thing only I have the replacement sender from the recall. I left for a fishing trip so I haven't worked on it yet but I'm pretty sure it's the sender. For me, it's easier to replace the sender first than it is to rip out the wiring under the boot cowl. I did that once before when the EMS unit started doing wacky stuff and it turned out to be the EMS unit.

I like to check continuity of the wires first so I'm interested in a response to your question.
 
tomkk said:
Last, but not least, I don't see the fuel pressure sensor (p/n 101690-000) on Van's site. Any idea where I'd find one?
Click to expand...

I have at least one of these in stock that, if nothing else, you could stick in to see if it's a sensor or wiring.
 
tomkk said:
Thanks. Is there a way I can check out the sensor. Is it a resistance that changes with pressure that I can check?
Click to expand...

The sensor is a voltage output. It needs +5V between the black and red wires and then it should put out 0.5V with no pressure and 4.5V with max pressure.

So check that you have 5V at the sender(you can unplug it and check the terminals). Then check the voltage on the green wire near the sender. If it's 0.5 to 4.5V, then you have an issue with the green wire. If it's out of that range, it's the sender or the connection right at the sender.
 
dynonsupport said:
The sensor is a voltage output. It needs +5V between the black and red wires and then it should put out 0.5V with no pressure and 4.5V with max pressure.

So check that you have 5V at the sender(you can unplug it and check the terminals). Then check the voltage on the green wire near the sender. If it's 0.5 to 4.5V, then you have an issue with the green wire. If it's out of that range, it's the sender or the connection right at the sender.
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Thanks, that's what it looked like from the schematics but good to have confirmation. I'll check that today.
 
Helpful

Once again, support from Dynon. This kind of support for their product is the reason that I will use Dynon exclusively in the future. I only wish that Van's would let me use the new Dynon com radio instead of the big G radio. :(
 
I recently had the opportunity to fly an RV-12 with G3X Touch screens. My 12 has the D-180 / D120 screens. The G3X is pretty cool, but we seemed to get a lot of spurious alarms. For my money I'll do Dynon every time!
 
fwiw, just to close on my original issue, I confirmed +5v input to the sensor and got +4.97v output on the green wire with no pressure at all (the fuel was disconnected from the sensor) so it looks like I have a bad sensor.
 
tomkk said:
fwiw, just to close on my original issue, I confirmed +5v input to the sensor and got +4.97v output on the green wire with no pressure at all (the fuel was disconnected from the sensor) so it looks like I have a bad sensor.
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I just check my sensor and got the same reading on my green wire. I've contacted Dynon to see about sending it back and getting it replaced.
 
You will have 5V on the green wire unless the sender is connected. Are you getting 5V with the sender connected?
 
dynonsupport said:
You will have 5V on the green wire unless the sender is connected. Are you getting 5V with the sender connected?
Click to expand...
Not sure. I had the sensor connector attached to the sensor but I disconnected the green wire where it attaches to the harness in order to make the measurement. Not sure how to measure the voltage with the green wire connected.
 
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tomkk said:
Not sure. I had the sensor connector attached to the sensor but I disconnected the green wire where it attaches to the harness in order to make the measurement. Not sure how to measure the voltage with the green wire connected.
Click to expand...
I was going to try to get a voltage measurement at pin 8 of WH-00020 where it goes into the SV-EMS-220 but I'm not why that would be any different than measuring it where the green comes out of the sensor. I have to disconnect the circuit to take the measurement, it shouldn't matter where I do the disconnect. Am I missing something?
 
If the green wire from the EMS has about 5V on it with no sensor connected, you have a good connection to the EMS.

If the wire out of the sensor has less than 0.5V or more than 4.5V (with or without it being connected to the EMS) then the sensor is bad.

So you can check continuity to the EMS by probing the connections at the sensor connector. You should have 5V between black and red and black and green.

Then, with the sensor powered, and either connected or disconnected to the EMS, you should have 0.5V with no pressure on the sender.
 
dynonsupport said:
You will have 5V on the green wire unless the sender is connected. Are you getting 5V with the sender connected?
Click to expand...

In my case, yes, the sender was connected and powered up. I have clips where I spliced in the replacement sender so I have easy access to the wires while the sender is installed.
 
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dynonsupport said:
... If the wire out of the sensor has less than 0.5V or more than 4.5V (with or without it being connected to the EMS) then the sensor is bad. ...
Click to expand...

Got it, thanks for clarifying. That's where I measured the 4.97v. Called tech support today and a replacement is on the way. I've heard others talking about great Dynon support, now I've seen it myself. Thanks.

f1rocket said:
... I have clips where I spliced in the replacement sender so I have easy access to the wires while the sender is installed.
Click to expand...

Yeah, I did the same thing. Makes trouble shooting a bit easier.
 
tomkk said:
Got it, thanks for clarifying. That's where I measured the 4.97v. Called tech support today and a replacement is on the way.
Click to expand...

Tom, did you install the replacement and did it fix your problem? I have a new sensor on the way and was curious if it is the resolution. Thanks.
 
Just got my new sensor yesterday and installed it today. The new sensor also fixed my problem so I'm back up and running.

I've used auto fuel exclusively and I read in another thread that it might be advisable to not have the sensor located lower than the fuel distribution spider because fuel gets trapped in that low spot and the natural deterioration of the auto fuel might cause a problem in the sensor.

Don't know if that had anything to do with my sensor failure but, just in case, I also relocated sensor to a higher location. I moved the sensor bracket up to the side of the GPS antenna tray, so sensor is higher than the fuel distribution banjo bolt and oriented horizontally.
 
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