912iS Fuel Pressure fluctuations

DBRV10

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Jun 15, 2008
Messages
505
Location
Brisbane, Qld. Australia
I have a customer with a 912iS and complete Skyview system. Everything is working great, except we seem to have fuel pressure variations from 37-44 PSI.

The sensor has once held a value with no pressure in the system, cycling the pump made the sensor respond and fall back to 0. So while it could be a faulty sensor, I don't think so. Yes it is the correct one and the correct setup.

So with the sensor/MAP/ambient pressure derived fuel pressure, I would expect the indication to be fairly consistent, but it appears that when you have reduced MAP during descent and landing the indicated pressure drops to around 36-37PSI. According to Rotax manuals this is bad.

I would like to hear from other users of what actually goes on, or does my customer have a pressure regulator problem?

Keen to be educated on my first 912iS experience.
 

porterjames

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Sep 26, 2016
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I have a 912iS and Skyview system.
At about 100 hours time in service I began to have fuel pressure fluctuations. After about 20 to 30 minutes in cruise flight the pressure would drop to around 37 psi. According to the Rotax Service Center the fuel pressure regulator is seldom, if ever, a problem. I checked for debris in the regulator just in case (found none) and replaced the fuel sensor. No problems since.
In answer to your question, my fuel pressure never deviates from around 42 or 43 psi (with one pump on) and around 44 psi with both pumps on. I have never had the fuel pressure drop below those values, regardless of configuration or power setting (other than when the sensor was faulty as mentioned above).
I know you said you verified that the sensor was correct- 101692-000, Injected Fuel Pressure-Kavlico, 1/8-27 NPT, 75 PSI .
There are other possibilities of course, one is fuel vaporization. This would cause a drop in fuel pressure.
 

DBRV10

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Joined
Jun 15, 2008
Messages
505
Location
Brisbane, Qld. Australia
Thanks for your reply. So what do you attribute the correction to? You say you replaced the fuel sensor, which I assume to mean the fuel pressure sensor?

And yes it is the 101692-000 sensor. I even decoded the manufacturers number to check :)

The SFG file is the latest, and the latest software. It is as though the software is not accounting for MAP or not doing the MAP/QNH correction at all.

Might be time to buy another sensor.
 

porterjames

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Sep 26, 2016
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That is correct, I replaced the fuel pressure sensor and that solved my fluctuation in fuel pressure indications.
 

sunfish

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Jan 21, 2013
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Is it worth checking that the MAP isn’t fluctuating? I believe there have been issues with the connectors.
 

djones

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Jul 19, 2010
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You also need to make sure the correct sensor is selected in sensor input mapping. In this case there are two different Kavlico 75 psi sensor definitions. For the Rotax 912is you need to make sure to select the KAV 75 PSI DIFFERENTIAL (101692-000)
 
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