m20k fuel senders and engine monitor install

[FloridaMan]

Going to install an EDM-900 in the Rocket. One shop told me that since my factory fuel gauges were accurate to not touch them and that the 1981 M20K used high frequency (not resistive) fuel level senders that would have to be rebuilt or I would lose any chance of having the same level of accuracy on the EDM-900. Can someone confirm this? I'd like to remove the entire gauge cluster, but if I'm risking screwing up by touching those fuel level gauges, I'd rather just leave that feature off of the JPI. 

[KSMooniac]

You should consider installing the CIES senders along with the 900. That will stop any concerns.

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[Marauder]

Going to install an EDM-900 in the Rocket. One shop told me that since my factory fuel gauges were accurate to not touch them and that the 1981 M20K used high frequency (not resistive) fuel level senders that would have to be rebuilt or I would lose any chance of having the same level of accuracy on the EDM-900. Can someone confirm this? I'd like to remove the entire gauge cluster, but if I'm risking screwing up by touching those fuel level gauges, I'd rather just leave that feature off of the JPI. 

I would be curious to understand if frequency type senders were part of the upgrade to a Rocket. That is one of the versions the CiES senders you can buy. I would be really surprised if they updated them to frequency since the original K gauges for 1981 were definitely analog resistive.

Are your gauges factory original for fuel? If they truly are frequency senders, you can still purchase a JPI 900 version that can be set and run in frequency mode.


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[ArtVandelay]

What year?
Since the Js used resistive I find it hard to believe the Ks were different.
I used existing resistive senders, I had to overhaul 1 that I thought was good (enough for analog), but digital would read sporadic spikes. I have 3 ways of reading fuel levels: wing mounted gauges, factory senders to JPI, and fuel flow total. The factory reads a little lower, but that’s because my JPI is configured for 32.0gal per side, when actually its 33.5. Not wanting to redo the calibration I left it alone, having 3 gallons more then factory specs isn’t a bad thing.

[flysamo]

install jpi 900 in my ovation, AV company had a hell of time to get set of wing fuel levels to work correctly, replaced both indicators in one wing and every thing works, found out that jpi recommends replacement of fuel senders after the fact, cheaper to replace then trouble shoot

[carusoam]

Antares,

sounds like checking the details are in order...

It is unlikely, that the K got frequency type floats while every other Mooney got resistance type floats...

Unlikely, but not impossible...  

You could work with a parts manual, Lasar, or look at the sensor itself to find out what senders you have...based on part numbers....

what makes the Cies gauges interesting is the number of divisions from empty to full.  Then they add a few things like average the details over a few seconds to give really accurate numbers without any flickering.... or so they described while working on the Mooney installs and testing...

So, in the end... frequency vs resistance doesn’t make one better than the other... number of divisions from empty to full, does... using a digital platform makes the data even more usable...

Integrating with JPI is going to be important.... knowing what sensors you actually have is going to be important there as well...

PP thoughts only, not a mechanic...

Best regards,

-a-

[Jeev]

On 7/22/2018 at 8:52 AM, flysamo said:

install jpi 900 in my ovation, AV company had a hell of time to get set of wing fuel levels to work correctly, replaced both indicators in one wing and every thing works, found out that jpi recommends replacement of fuel senders after the fact, cheaper to replace then trouble shoot

This is often times true and can save time and money in the long run but as some have noted the factory gauges can work too, JPI does recommend the CIES senders with EDM 900 and 930's.  I would definitely verify what senders you have by part # before going any further.  The CIES sensors are well made and stand up to the claims of accuracy but are not cheap at around $1,600 for the K however you are preatty much guaranteed an accurate fuel reading and they last a long time.  Also if you plan on doing the senders its better to do so when you first purchase the EDM 900 so you can have it configured for the digital CIES senders.  If you do it later JPI charges around $300 for the change.

Please let me know if I can help with any additional info.

Sanjeev

Wolf Aviation

sanjeev@wolfaviationsales.com 

[Marauder]

This is often times true and can save time and money in the long run but as some have noted the factory gauges can work too, JPI does recommend the CIES senders with EDM 900 and 930's.  I would definitely verify what senders you have by part # before going any further.  The CIES sensors are well made and stand up to the claims of accuracy but are not cheap at around $1,600 for the K however you are preatty much guaranteed an accurate fuel reading and they last a long time.  Also if you plan on doing the senders its better to do so when you first purchase the EDM 900 so you can have it configured for the digital CIES senders.  If you do it later JPI charges around $300 for the change.
Please let me know if I can help with any additional info.
Sanjeev
Wolf Aviation
sanjeev@wolfaviationsales.com 

When I installed the CiES senders last year, JPI was anything but happy with the CiES. They certainly weren’t recommending them. Mainly because Scott from CiES was telling people like me at Oshkosh that their senders were drop in replacements. Sorta true if you run them in resistive mode. But if you have an older JPI, you’ll need to fork up $350 to have the firmware updated and a cable sent. New JPIs have the CiES as an option that you can order (I suspect this is why JPI is happy recommending them now).


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[gsxrpilot]

I would start by finding a shop that is actually happy to install an EDM-900 in your Rocket. Evidently this shop hasn't done many, or hasn't had great success with the installs, or both. Either way, this means more expensive and less chance of success for you. And when features don't work, the shop will just say, "we told you so."

I'd find a different shop.

[fuellevel]

Yes JPI has come around.    Nobody in Aviation likes the new guy, that is a rule and probably in the CFRs   I wasn’t so popular here as well.    In later Mooneys there is a conversion box to take the analog resistive input and convert it.   I don’t have one,   but I suspect a voltage divider so that sensors from potential other manufacturers like Rochester could be used without changes to the instrument panel.    Resistive to Frequency wasn’t a big item back then as fuel totalizers using frequency were new.   This method was also applied to Bonanzas and Barons as another example.     In most cases with a new Engine monitor or engine information system this box goes away.    

Garmin EIS would be the only potential exclusion as it accepts resistance, voltage and frequency,   So the conversion  box could stay, but the active question for the install shop is why.    

[FloridaMan]

On 7/31/2018 at 10:48 AM, gsxrpilot said:

I would start by finding a shop that is actually happy to install an EDM-900 in your Rocket. Evidently this shop hasn't done many, or hasn't had great success with the installs, or both. Either way, this means more expensive and less chance of success for you. And when features don't work, the shop will just say, "we told you so."

I'd find a different shop.

It sure looks like a straightforward install to me. Things are a little tight on the Rocket, but at this point I fail to see anything that gives me cause for alarm or concern. If there is some supernatural complexity with the TSIO520 in this configuration that would make things fail to work, I would certainly like to know about it.