FT60 fuel flow transducer RV 0 reading Dynon HDX

[michelebrown]

I have installed an FT60 fuel flow transducer in my RV, but I am experiencing a constant reading of 0 on the Dynon HDX. The transducer is properly connected to the EMS-220 using the correct pins (13, 14, 15), but when measuring the voltage on the red cable from pin 15, I am only getting a reading of 7.95V. The instructions state that it should provide 12V. I suspect that this voltage discrepancy is the reason why the transducer is not functioning at all. Has anyone else encountered a similar issue? What voltage are you measuring at the transducer?

uno online​

 

[airguy]

I have installed an FT60 fuel flow transducer in my RV, but I am experiencing a constant reading of 0 on the Dynon HDX. The transducer is properly connected to the EMS-220 using the correct pins (13, 14, 15), but when measuring the voltage on the red cable from pin 15, I am only getting a reading of 7.95V. The instructions state that it should provide 12V. I suspect that this voltage discrepancy is the reason why the transducer is not functioning at all. Has anyone else encountered a similar issue? What voltage are you measuring at the transducer?

Where are you getting power from? Check your power source for good voltage first - then confirm good ground continuity. The device functions by having an LED shine a light source to a receiver, and the turbine wheel interrupts that beam of light as it spins. The LED source will indeed not like low voltage, the receiver is probably not very happy about it either.

 

[MacCool]

My FT-60 works fine getting 8v from my Dynon SV-220-EMS engine module (pin 15). It was a few years ago, but IIRC I talked to both Rob Hickman and someone at EI about that and they said "no problem".

 

[lr172]

I have installed an FT60 fuel flow transducer in my RV, but I am experiencing a constant reading of 0 on the Dynon HDX. The transducer is properly connected to the EMS-220 using the correct pins (13, 14, 15), but when measuring the voltage on the red cable from pin 15, I am only getting a reading of 7.95V. The instructions state that it should provide 12V. I suspect that this voltage discrepancy is the reason why the transducer is not functioning at all. Has anyone else encountered a similar issue? What voltage are you measuring at the transducer?

That is too low. While the transducer may work at 8 volts, you likely have a wiring problem that is preventing enough current to flow to run the transducer and hence the 0 reading. The low voltage is the clue to that. This is not just a few chips, but also a light source, so not dealing with ultra low current. First insure that the power out pin on the Dynon is givig 12 volts, then you need to re do the wiring. It could just be the connector pins or a flaw in the wire itself.

Larry

 

[MacCool]

That is too low. While the transducer may work at 8 volts, you likely have a wiring problem that is preventing enough current to flow to run the transducer and hence the 0 reading. The low voltage is the clue to that. This is not just a few chips, but also a light source, so not dealing with ultra low current. First insure that the power out pin on the Dynon is givig 12 volts, then you need to re do the wiring. It could just be the connector pins or a flaw in the wire itself.

Larry

What am I missing Larry? I read pin 15 on the EMS as being 8 volts, which corresponds to my measurements when I replaced the device a year ago.

..

 

[lr172]

What am I missing Larry? I read pin 15 on the EMS as being 8 volts, which corresponds to my measurements when I replaced the device a year ago.

..View attachment 55116

My apologies here. I only have experience with GRT and Garmin, both of which use 12 VDC for this transducer and had no idea that Dynon used 8 VDC. Should be fine, as most of these transducer chips only need a minimum of 5.5-6 volts to operate. However, I am not positive on what the red cube needs. It is more than a hall effect chip though, as it needs enough power to activate the LED light source.

The red cube should be sending square wave pulses that go from 0 -> whatever volts the dynoon is sending to be sunk by the cube. If you have 8 volts at the cube, next step is to check the ground at the cube as well as to check continuity on the signal wire.

EDIT; just looked up the specs and the cube requires 8-30 volts supply and only draws 15mA. An 8 volt feed is a bit on the low side, as you are right on the fringe of the operating specs. Kind of surprised that Dynon didn't use 12V here. I would still measure the resistance of the power feed and the ground, as any meaningful resistance here can drop you below 8 VDC. At some point, you can run a wire from the battery to the red cubes red wire to see if a higher voltage source makes it work.

 

[MacCool]

OK...thanks. I only know that for the last 12 years, my red cube has been working fine at 8 volts, as was suggested by both Rob Hickman and EI "tech support". Now...I did replace the red cube a year ago, like many others have reported, due to intermittent failure to display. Whether or not that ultimately happened due to 8 volts being a bit on the low side...I don't know.

I'd also note that my FT-60 is mounted on the firewall before the engine driven pump and boost pump...I've never seen fuel flow oscillations on the display.

 

[KRviator]

I have installed an FT60 fuel flow transducer in my RV, but I am experiencing a constant reading of 0 on the Dynon HDX. The transducer is properly connected to the EMS-220 using the correct pins (13, 14, 15), but when measuring the voltage on the red cable from pin 15, I am only getting a reading of 7.95V. The instructions state that it should provide 12V. I suspect that this voltage discrepancy is the reason why the transducer is not functioning at all. Has anyone else encountered a similar issue? What voltage are you measuring at the transducer?

Silly question but I'd better ask - have you actually told SkyView that there's now a FF sensor on Pin14? It's not just "Plug it in and she'll work"