Jump to content

Fuel Pressure Alarm


N751JM

Recommended Posts

  • Replies 50
  • Created
  • Last Reply

The CTLSi Aux pump makes too much pressure once the engine is running. I use it on engine start, I dont use it to takeoff on on approach landing.

 

The POH isnt giving out the right instructions for the CTLSi. The Aux Pump will always make the fuel pressure go yellow if you have it on while the engine is running.

 

Btw, I takeoff at 5,000 feet when at home.

 

Yellow zones on instruments are either cautions, or by common design in aviation on things like RPM, are fine to run in for short periods of time (5 minutes is a very typical period). If the aux pump is pushing fuel pressure into yellow, you should still use it, it just means you don't need to use it all the time.

Link to comment
Share on other sites

Too much fuel pressure with a carb could possibly overpower the needle and seat, causing an overly rich mixture.

 

Too much fuel pressure with an injected ROTAX???

 

Maybe someone needs to ascertain from them the reasons for the limitation, and the effects of ignoring it.

Link to comment
Share on other sites

The FI engine uses right around 45 psi and isn't prone to flooding with a little extra pressure like the carbs. Many Dynon units just need the upper alarm limit slightly adjusted. If you have the standard Dynon D120 the upper fuel pressure limit should be changed from 5.8 to 7.2 psi.

Link to comment
Share on other sites

  • 1 month later...

I just picked up a replacement VDO 30PSI fuel pressure sender from JEGS.  http://www.jegs.com/i/VDO/918/360-043/10002/-1?parentProductId=887192

There is a small insert in the package now that says not for use with fuel.  Maybe they know the thing is unreliable with fuel as it tends to varnish up and get flaky after a few years.  Also says not for use on aircraft, BTW

Link to comment
Share on other sites

Pretty soon they'll print it on the pilot license.  But "not for fuel" seems relevant.  I think they tend to bake fuel sitting on top on the engine which will relentlessly form varnish and eventually gum up the sensitive transducer. Isn't there another one that can be used that Dynon recommends?

Link to comment
Share on other sites

In order to install solid state oil pressure sensors, you had to make a current loop per 3-6 of the dynon installation guide: http://www.dynonavionics.com/downloads/Install_Guides/EMS-D120_Installation_Guide_Rev_H.pdf

 

I suspect that you would also have to make this loop if you use it for fuel pressure sensing with the solid state transmitters, since the wiring is similar VDO fuel sensors as with the old VDO oil sensors. A simple call to the Dynon techs will resolve that really quick. Chanik, you could probably tell them you are an electrical engineer; when I told them I'm an A&P with avionics experience, they immediately opened up with tech language instead of trying to use layman's terms that wasn't getting us anywhere :).

 

Also, for those who might ask in the future: Rotax doesn't use kavlico anymore. They went kavlico > honeywell > some new manufacturer (I can't remember the name, but this is the sensor I currently have). However, they are all functionally the same.

Link to comment
Share on other sites

No, but it does want a +5V input which means running another wire from the D120 backplane connector.  More simply, I would just come off the main battery and put a tiny low quiescent draw 5V LDO right at the unit.

http://www.dynonavionics.com/downloads/Install_Guides/Addendum_Kavlico_Sensors-Rev_B.pdf

 

Be sure to fuse it then so you don't inadvertently damage your panel! :)

 

Also, I was wondering where that page was. I was scouring my documentation trying to find it, didn't realize it was in it's own manual addendum pdf!

 

Anyways, I had tried to use the new solid state oil pressure sensor WITHOUT wiring per 3-6 of the D120 installation manual, but it didn't work until I added the current loop. Just an extra tidbit that might be useful to you, chanik, if you have problems with it :).

 

EDIT: One more thing. The sensor will have three pins in the newest design as of this post (the one I am using). If you read the latest rotax "running modifications" instructions letter, it tells you that one of the pins are not used. The sensors can output a variable voltage in one design, but a variable current in another design. Both of these sensors have the same physical build (three pins), but it matters how they have made the internal circuitry, according to the sensor manufacturer, so one of those pins will be non-functional.

 

EDIT 2: Here's the rotax running modifications bulletin: http://legacy.rotaxowner.com/si_tb_info/serviceinfo/si-912-020r7.pdf . Relevant information is in section 79-00-00, pages 1 through 3.

Link to comment
Share on other sites

  • 3 years later...

Hi all, when installing the Kavlico solid state sensor (P/N 101690-000), is it ok to just replace the VDO one and screw it in, in the same spot with a smaller adel clamp with the pressure fuel line pointing down on the firewall as per factory installation (CTLS)? (This is just a question re installation, not the electrical). And does it need a seal on top of the thread, which is not supplied as per Kavlico documentation? Thanks for any feedback.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.


×
×
  • Create New...