Jump to content

Gallons Per Hour


FMay

Recommended Posts

EMS-D120 

  • GPH fuel display is showing 8-9 GPH in level flight at 5250 rpm. The book doesn’t show how to change fuel  consumption . Only adding gallons of fuel to the monitoring system.

Does anyone know how this can be changed?

Link to comment
Share on other sites

On a related note, does anyone have figures for "normal" and "high" fuel flow?  My normal looks good ranging from 4.6 at low power to 5.3 at higher power settings  BUT I've been getting "Fuel Flow High" alarms for a few seconds on takeoff just before liftoff.  Self cancels after only a few seconds but distracting during a critical phase of flight.  Dynon is set at 10.3 for HIGH flow alarm.   Rotax manuals seem silent on the subject.

 

 

 

Link to comment
Share on other sites

That's normal and seen everywhere. You'll notice it coincides with fuel pressure changes. I standby my belief that we have vapor issues that get trapped in the fuel pump and take a moment to clear. Once the vapor is pushed out and hits a carb, the whole system has a momentary speedup of fuel flow due to rapid displacement of gas.

Link to comment
Share on other sites

22 hours ago, EricB said:

On a related note, does anyone have figures for "normal" and "high" fuel flow?  My normal looks good ranging from 4.6 at low power to 5.3 at higher power settings  BUT I've been getting "Fuel Flow High" alarms for a few seconds on takeoff just before liftoff.  Self cancels after only a few seconds but distracting during a critical phase of flight.  Dynon is set at 10.3 for HIGH flow alarm.   Rotax manuals seem silent on the subject.

 

 

 

Just curious, what RPM numbers are you using for "low power" and "high power"?

IIRC the 912ULS docs from Rotax list cruise RPM numbers down to 4600rpm, which would be very low fuel consumption, around 4gph.  Up at the high end I think you can get the engine to burn around 6gph, but you're at a setting that doesn't buy you any appreciable speed more than a lower RPM around 5.3-5.5gph.

Link to comment
Share on other sites

On 9/4/2024 at 1:16 PM, EricB said:

High power would be 5000 - 5300 or so

Low power 3500 or so.  In between , call it medium

 

Really? 

5000-5300rpm to me is normal cruise power, above 5400+rpm would be "high power".  Anything 4800rpm or below is "low power" in my mind.  3500rpm is really, really low power, nobody would cruise at that power setting unless they're trying to keep pace with an ultralight. If you are burning 4.6gph at 3500rpm (the "low" fuel flow you mentioned), you need to check for fuel leaks!  😁 (or more likely check your flow calibration)

I occasionally fly alongside a buddy in an Avid at 3800-4000rpm, and I bet my fuel flow is about 3.8-4gph. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...