Lower Range Fuel Pressure Transducer

[daveg]

I am currently using a Dynon D180 with a Jabiru 3300 powered Zodiac 601XL.  The nominal operating fuel pressure is in the range of 1.5 to 2.0 PSI.   The 30 PSI transducer supplied for carbuerated engines is at it's very low end in my application.  I get a fair amount of "low fuel pressure" alarms that I am sure are just due to the in-ability of the transducer to be very precise that low.

Are there any plans in the future for Dynon to supply a smaller range transdcuer??  If not, it would be nice to know if there was a known smaller range transducer that could be installed and calibrated with the Dynon EMS's

Thanks,

DaveG

 

[dynonsupport]

We don't have current plans to introduce any new pressure transducers, but this is largely because we haven't seen many problems at all with the ones we currently offer. Is it possible that you are seeing real momentary dips in fuel pressure from fuel sloshing, etc. I don't know what the specs are for the 3300 without doing more research, but are you using the bottom of a nominal range as your redline value, or a lower value than that?

 

[lwhitlow]

Hey there Dynon Guys

This discussion started on the Jabiru Engines list and a number of us have carried it over here for your thoughts

The Jab 3300 had a Bing altitude compensating carb installed and the engine has a mechanical fuel pump fitted in front of the carb.

The Bing expects to see pressures in the 1-2.5 PSI range in normal operation, and if the pressure gets much over 3 PSI then the pressure forces open the float valve in the bowl and that is usually classified as "NOT A GOOD THING" (tm)

Our discussion turned to the fact that we are using less than 5% of the VDO sender  Dynon supplies (0-30 PSI IIRC) and just how accurate it would be in the 0-3 PSI range we are looking at.

We know of other sensors  of a more optimal range that could be used but the Dynon only supports the VDO.  It could be a simple matter of a different look-up table to support another sensor, or giving us the means to calibrate the Dynon to a different sensors range.

Anyway, this discussion is just a way of making sure we are getting the best data from the engine thats possible and to see if there are alternatives to what we are doing.

Thanks for a great product and really doing your best to listen to what we look for and to try and stay ahead of the crowd!

Larry Whitlow
601 XL

 

[dynonsupport]

What are the other sensors? We may be able to do tables for them, we may not.

 

[lwhitlow]

I have identified one 0-7 PSI sender and two 0-15 PSI senders that look to fit the bill

From the Aircraft Spruce Catalog

UMA Pressure Sender (U) 0-7 PSI Differential 10-00980
UMA Pressure Sender (U) 0-7 PSI                10-01057

From any online auto parts and/or marine parts supplier
Stewart Warner 114874
Hardin Marine 105-25480 (this unit is listed for a high vibration install)

The UMA units are priced around $100 and the other units come in around $40

Guys, we all really appreciate you just taking the time to see if its possible. We understand that even if it is possible, you might not be able to add support for these senders to the product, But it never hurts to ask!!!

Thanks
Larry Whitlow
601XL

What are the other sensors? We may be able to do tables for them, we may not.

 

[DavidRose]

Hi Dynon Support,

Rotax users are in the same place as the Jab guys. Our 912s have Bing carbs that have a fuel pressure range of 2 to 5.8 psi.

Supporting a lower range sensor would be great for us - and there are alot of us!

Thanks

 

[dynonsupport]

Sorry for never getting back on this.

As I mentioned in the other thread, the UMA sensors won't work because of the way the sensor outputs (they can't drive against a resistor), and the Stewart Warner senders have been tested and are highly inaccurate (much worse than the current sender). We'll see if we can get one of the Hardin ones and if it's any better.

 

[PhantomPholly]

Just for grins, how accurate IS the Dynon supplied sensor and is it possible to display more digits of precision?

 

[dynonsupport]

It's always possible to give you more digits on the screen. As to if they are "precision" of not...

I can't answer the question as to how accurate the current senders are. We calibrated a few many years ago and they were acceptably repeatable, unlike the Stewart Warner. Specific numbers I don't have, but a 1PSI offset variance between units on a 30 PSI sender would pass our limits, so a constant 0.06 BAR offset wouldn't be a failure.

 

[JR]

Any progress on this?

 

[dynonsupport]

We have not yet found a sender that is more accurate than the one we currently use, and we have tested all of the ones listed in this thread. We're still open to suggestions.

 

[JR]

What input can the fuel pressure channel handle?
I can get a small transducer 0-25psi but outputs 0-5V, runs on 12vdc
Any way of using something like this?
JR

 

[dynonsupport]

Possibly, depending on the exact characteristics of the sensor. If it's an UMA sensor, it probably won't work due to the way they're driven. Note that all sensors need to be evaluated and characterized here before they can be used - you can't just hook any sensor up and have it work.

What's the sensor (brand, model, etc) that you have in mind?

The main issue is finding a sensor that has enough resolution and sensitivity at the very low pressures. None that we've found so far do a phenomenal job.

 

[JR]

Made by Kavlico Model P155, Stainless, 0-15psi range, requires 5vdc to drive it though www.omniinstruments.net

I have found a 12vdc one but its 0-25psi

 

[JR]

Bump, is there any progress on this?
Did you look into these transducers?
0.5 to 4.5 VDC, needs 5mA @ 5vdc to run, 100 Ohm impedance