Rotax fuel flow too high

[paulrkuntz]

I have a Skyview installation for a Rotax 912, with two EI fuel flow sensors - one for fuel supply, one for return. I am getting fuel flow readings that are more than twice as high as the actual fuel flow, with both sensors configured for 68,000 pulses per gallon as recommended. When I computed the adjustment factor today, I got 2.22, which produces a new value of 151,000 for pulses per gallon. This value is so large that the system will not accept it as a valid input. Something basic is wrong. Anyone have some idea where to look?

 

[mmarien]

Check to see if the second (return) cube is working. There is a status display in the sensor setup.

 

[Dynon]

What mmarien said. Look at EMS SETUP > SENSOR DEBUG DATA to ensure that they're both counting. If the return line wasn't counting, you'd get too high a perceived flow rate.

 

[paulrkuntz]

Thanks for the tips. When I checked the sensor debug data page I found that I had never configured the return fuel flow sensor. After I configured it, filled the tanks and flew a few hours to generate a new calibration, I am now getting total fuel flows that look reasonable, and calculated fuel consumption that is pretty close to actual consumption. A couple of additional tweaks and I should be right on. The only thing that bothers me is that I am getting a pulses per gallon setting of about 110,000 but the manual says the EI flow sensor value is normally 68,000. What would cause my value to be so different from the expected value?

 

[Dynon]

So what do you have set for both of your individual k-factors?

 

[paulrkuntz]

Both individual K-factors (main and return) are set to the same value. My last tank fill-up showed that I am within about 5 percent between computed and actual fuel consumption, so I am close. The new value is about 103,000. That's still far off from the expected 68,000 so I'm still wondering if there's a problem somewhere.