Fuel Flow Cube

[mike.smith]

Hi Mike,

I'm curious. What are the exact problems you are encountering?
What type of EFIS is the Gold Cube connected to?

MGL Xtreme Mini.

Fuel flow in cruise can show 9 gph one minute, then 3.5 gph the next. And anything and everything in between. It's like that in every flight mode. Even when nothing changes, the fuel flow does. I consistently burn an average of 4.5 gph as measured by actual fuel use. So I know in cruise I should be seeing something like that most of the time. I rarely do. I have a graduated visual fuel sight tube, so it's pretty easy to cross check fuel use in flight, too. When I dip the tank after a flight I NEVER get even a close match on the fuel-remaining read out. So I have to manually reset it to the actual value.

[XenosN42]

Hi Mike,

Thanks for the details. I've used the Gold Cube for about 11 years. Five in my Xenos and now six in my OneX. Both have worked perfectly until about 4 months ago. Since then the fuel flow in the OneX has consistently indicated about 20% lower than expected. However, the power output (RPM), CHTs & EGTs and any other observed values have not changed. Therefore, all evidence points to the measured fuel flow being incorrect.

I've also seen odd transient spikes in the fuel flow reading. It reads a constant value then shoots up to 80 GPH for a second only to return to normal. Never experienced that before.

Could be either the Gold Cube or the MGL Explorer EFIS. No clear data proves the fault is in one or the other. The only way I can think of to eliminate one would be to replace the Gold Cube and observe the result.

[GraemeSmith]

I asked elsewhere but didn't get an answer. Does anyone use a "pull up" resistor to get their EFIS to read the cube?

[mike.smith]

If anyone is curious what the Gold Cube looks like inside...
https://www.youtube.com/watch?v=HXJMLcpcl10

[XenosN42]

I asked elsewhere but didn't get an answer. Does anyone use a "pull up" resistor to get their EFIS to read the cube?

I have used a 5600 ohm resistor on both my Gold Cube / MGL installations. Installation instructions: https://support.michiganavionics.com/portal/api/kbArticles/500733000001263225/locale/en/attachments/1hflqd90b8a89eda849e6b3eb88a5eb6a0e96/content?portalId=edbsnf81d70f15908a70949bfab1c6d8894b811a79c962862c03fe12b8cbd658104da&inline=true (Note: the picture in the documention shows a red cube, but the instructions are the same for the red and gold cubes. )

[mike.smith]

I asked elsewhere but didn't get an answer. Does anyone use a "pull up" resistor to get their EFIS to read the cube?

I have used a 5600 ohm resistor on both my Gold Cube / MGL installations. Installation instructions: https://support.michiganavionics.com/portal/api/kbArticles/500733000001263225/locale/en/attachments/1hflqd90b8a89eda849e6b3eb88a5eb6a0e96/content?portalId=edbsnf81d70f15908a70949bfab1c6d8894b811a79c962862c03fe12b8cbd658104da&inline=true (Note: the picture in the documention shows a red cube, but the instructions are the same for the red and gold cubes. )

I have that on my Gold Cube installation but it still doesn't work for me.

[XenosN42]

Hello all,

A few weeks ago I posted about a problem with my Gold Cube fuel flow sender. It was reading too low. After that post I did a one hour flight, beginning with a full fuel tank. After the flight I topped it off with ~ 4.3 gallons, which matched what I assumed my AeroVee burns per hour. The reading from the Gold Cube was in the 2.6 gallon/hr range.

So I bit the bullet and purchased a replacement Gold Cube. As an aside I ordered it from Aircraft Spruce. I placed the order at around 11am and it arrived around 10 am THE NEXT DAY! That was with standand shipping. What great service. Admittedly I live in eastern PA and it was shipped from western PA.

It was easy and quick to swap out the senders. And the verdict? The old sender was bad. So much for the vendor's claim of a 10,000 hour service life.

Here are the results of the RPM vs fuel flow tests:

[pfhoeycfi]

Hello all,

A few weeks ago I posted about a problem with my Gold Cube fuel flow sender. It was reading too low. After that post I did a one hour flight, beginning with a full fuel tank. After the flight I topped it off with ~ 4.3 gallons, which matched what I assumed my AeroVee burns per hour. The reading from the Gold Cube was in the 2.6 gallon/hr range.

So I bit the bullet and purchased a replacement Gold Cube. As an aside I ordered it from Aircraft Spruce. I placed the order at around 11am and it arrived around 10 am THE NEXT DAY! That was with standand shipping. What great service. Admittedly I live in eastern PA and it was shipped from western PA.

It was easy and quick to swap out the senders. And the verdict? The old sender was bad. So much for the vendor's claim of a 10,000 hour service life.

Here are the results of the RPM vs fuel flow tests:

Is there a reason to use the Gold Cube rather than the Red Cube? Doesn't the Red Cube have a lower minimum gpm? I installed the Gold Cube but I'm questioning my selection. I haven't run the engine yet waiting on a prop.
Peter

[GordonTurner]

It looks to me like the flow difference that is significant is at flow rates significantly higher than anything we are using. Fir our little motors the red cube doesn’t present an obstruction to gravity fed systems. If you’re the guy with the O-540 on hi is Sonex, then you would be better advised to stick with the gold cube.

[GraemeSmith]

It looks to me like the flow difference that is significant is at flow rates significantly higher than anything we are using. Fir our little motors the red cube doesn’t present an obstruction to gravity fed systems. If you’re the guy with the O-540 on hi is Sonex, then you would be better advised to stick with the gold cube.

Notwithstanding our modest fuel flow needs and a lot of folks indicating success with red cubes.

The Gold Cube is indicated for Gravity Carbureted and Injected Engines

The Red Cube for engines supported by a fuel pump.

As they are both the same price at Aircraft Spruce at this time - Go with the Gold! :-)