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High Fuel Flow readings

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yankee-flyer

Well Known Member
Did the second engine start, fuel system calibration, taxi test, and runup today. At full throttle I get a High Fuel Flow alarm (10.4 gph), and at 2500 rpm the fuel flow reads 5.8 gph. I don't think that's corect (temp 80 deg, density altitude about 1600 ft) since we weren't dumping fuel overboard or on fire, so I hope there's some calibration I can do to get more reasonable numbers. What and where? Getting impatient to fly this thing!

Wayne 120241 N143WM soon?
 
Wayne,

What do you have your K Factor set at? That will certainly influence your fuel flow. It should have been on a card that was wired to your electric fuel pump when you got it. I seriously doubt that you are running 10 gal/hr. Mine is set at 46,000 but they are all different.
 
See Dynon Install manual pg 6-14.

Because of the return fuel flow the flow transmitter needs to be set high.
 
Also make sure you didn't install the dual hose assemble located on the top of the engine, backwards. That would position the flow restrictor in the wrong hose path and allow a very high flow in the return line to the tank.
 
Pressure and flow issues

If the restrictor was installed backwards would it produce low fuel pressure and a high flow rate? I can not get my pressure much over 3.0 psi and the aux pump by itself only reaches 0.8 to 1.0 psi.

Here is a picture showing my rpms at 4710 but my flow was 6.6 and the psi was 2.7. I have the red cube and the K was setting at 96500. I've checked the gascolator screen, the flow out of the gascolator and the flow to the fuel pressure sensor and it all looks good.

I'll double check the assemble tomorrow.

http://picasaweb.google.com/ronedmark/Misc#5541704137749426162

Thanks,
-Ron
 
redmark said:
If the restrictor was installed backwards would it produce low fuel pressure and a high flow rate? I can not get my pressure much over 3.0 psi and the aux pump by itself only reaches 0.8 to 1.0 psi.

Here is a picture showing my rpms at 4710 but my flow was 6.6 and the psi was 2.7. I have the red cube and the K was setting at 96500. I've checked the gascolator screen, the flow out of the gascolator and the flow to the fuel pressure sensor and it all looks good.

I'll double check the assemble tomorrow.

http://picasaweb.google.com/ronedmark/Misc#5541704137749426162

Thanks,
-Ron
Click to expand...

That is exactly what the symptoms would be.
You need to check and see if you have the sensor/fuel return hose installed backwards.
 
I double checked the VA-216 line and confirmed the black fitting was connected to the fuel pressure sensor and the yellow fitting was connected to the return fuel line. I even pulled both fittings and did the blow test to see if the yellow side was more restrictive and it was. I checked the clamp block and made sure the jets were removed.. good too. The gascolator screen is clean and I'm getting a good flow from it all the way to the fuel pressure sensor.

Also I checked all the d-sub connections and they looked solid. I powered on the Dynon change the K value to 68000 (red cube). Without the engine running I'm seeing 2.2 gph flow and 0.2 psi of fuel pressure. I measured the voltage across the fuel pressure sensor and it was 202.3 mV. I assume that equals the 0.2 psi?

Bad fuel pressure sensor or fuel pump? With the engine running I'm getting around 3.0 psi. The first 3 hr. of running the engine I don’t recall seeing pressure problems. Only after 1.2 hr. of the first phase did this popup.

I did notice one thing when I pulled the line off the fuel pressure sensor… the fuel that leaked out was tinted orange-ish? More poured out the sensor when I shook it. Any ideas what that could be?

Thanks,
-Ron
 
Fuel pressure

Ron,
The fuel that I drained from the gascolator had an orange tint. I think it comes from the gas station that color.
I measured the voltage at 0.166vdc across the fuel pressure sender with the engine off and the electric fuel pump fuse pulled out, if that will help you any. A pressure gauge could be temporarily connected to verify the Dynon fuel pressure reading.
Joe
 
K-Factor

I set my K-factor around 96000 (forget exactly what) and the problem went away. I'm collecting data to set it more accurately, but at 96K I have no fuel flow alarms and pressure looks good-- so far!

Wayne 120241
 
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