CIES fuel senders vs overhaul

[rwabdu]

Getting  factory fuel gauges checked possibly overhauled in my m20c as the first step in finding out why they are not even close to accurate. Looking for opinions on anyone who has replaced senders with the CIES senders (if it turns out not to be a gauge problem). Did you keep your factory gauges or buy the digital gauge? if so, would love to get some ballpark on how much time it takes a mechanic to replace the factory gauge with the digital one? Seems like I can get the factory gauges and senders overhauled for a few hundred dollars. Wondering if there is an reason to get the CIES senders without upgrading from the factory gauge. As usual, the bottom line comes down to cost. Thanks for any advice. 

[DXB]

The CiES senders with digital gauges are far more reliable and accurate, particularly at lower fuel quantities, than perfectly working stock senders. Whether or not to spend the extra cash to upgrade might be guided by whether you ever fly missions down to minimum fuel reserves and how long you plan to keep the plane.  If you keep the plane a long time, it's more easy to justify spending on vastly superior modern replacements when antiquated stuff goes bad because you'll have longer to enjoy the benefit of the upgrade.  When I fly longer trips, the added peace of mind provided by the CiES senders backed up by fuel totalizer data is worth a lot - there are some longer legs I would not have attempted without them.

[KSMooniac]

I agree. I world also ask if you have a fuel totalizer/flow gauge too. That will help you know exactly how much fuel you have, provided you don't have a big leak somewhere. Having both is best!

I have the totalizer/flow from my EDM 900, but will upgrade senders to CiES in the next few months. They weren't available for Mooney when I did the EDM upgrade, and my factory senders still suck.

Sent from my LM-V600 using Tapatalk

[DXB]

5 minutes ago, KSMooniac said:

I agree. I world also ask if you have a fuel totalizer/flow gauge too. That will help you know exactly how much fuel you have, provided you don't have a big leak somewhere. Having both is best!

I have the totalizer/flow from my EDM 900, but will upgrade senders to CiES in the next few months. They weren't available for Mooney when I did the EDM upgrade, and my factory senders still suck.

Sent from my LM-V600 using Tapatalk
 

In case you haven't figured out already, you will likely need to send your EDM900 back to  JPI for a firmware upgrade to accept the digital senders - they wouldn't let my avionics shop do it in the field.  The new firmware also has some quirks that still continue to annoy me.

[Jpravi8tor]

On another note but somewhat related...Does anyone make or use a calibrated dip stick to verify their fuel loads? I would certainly like to have one for my 75 F model

[DXB]

11 minutes ago, Jpravi8tor said:

On another note but somewhat related...Does anyone make or use a calibrated dip stick to verify their fuel loads? I would certainly like to have one for my 75 F model

I made one for the 27.4 gallon/side bladders. I think there are plenty of folks here who have the measurements for the standard wet wings.

[Skates97]

17 minutes ago, Jpravi8tor said:

On another note but somewhat related...Does anyone make or use a calibrated dip stick to verify their fuel loads? I would certainly like to have one for my 75 F model

I have one of these, easy to calibrate and you'll know within a gallon what you have on board. I have the CIES senders and an EDM900 which is a very accurate setup. I still dip the tanks before each flight. There are a lot of things that could go wrong on a flight, the one that I should be able to prevent is to never run out of fuel. 

https://www.aircraftspruce.com/catalog/pspages/fuelhawkuniv16.php?clickkey=11785

[DCarlton]

I bought a spare overhauled gauge for my left side.  Installed it and noticed how differently it responds from the previous gauge or right side.  Just for grins, I'm planning to get my original left side overhauled and then compare the two on the left.  I use time and max fuel burn almost exclusively to measure fuel used.  The gauges put me in the ballpark.  When I get my tanks resealed I'm thinking of upgrading to CIES senders but I've flown with the current gauges for almost 20 years.  Flying with an IO-360 is easy though.  Would be much more difficult with some other engines where fuel flow varies so much.  

[Ragsf15e]

1 hour ago, rwabdu said:

Getting  factory fuel gauges checked possibly overhauled in my m20c as the first step in finding out why they are not even close to accurate. Looking for opinions on anyone who has replaced senders with the CIES senders (if it turns out not to be a gauge problem). Did you keep your factory gauges or buy the digital gauge? if so, would love to get some ballpark on how much time it takes a mechanic to replace the factory gauge with the digital one? Seems like I can get the factory gauges and senders overhauled for a few hundred dollars. Wondering if there is an reason to get the CIES senders without upgrading from the factory gauge. As usual, the bottom line comes down to cost. Thanks for any advice. 

Just to be a bit contrarian, my factory senders work great.  They were OHd when the prior owner put in a jpi930, and they are accurate down to +-1 gallon as far as i can tell.  Close enough for me since I never want to get close to needing more accuracy.

I think you’ll find that your gages aren’t going to read very well even with accurate senders.  And cies senders won’t work with those gages anyway.

[DCarlton]

7 minutes ago, Ragsf15e said:

Just to be a bit contrarian, my factory senders work great.  They were OHd when the prior owner put in a jpi930, and they are accurate down to +-1 gallon as far as i can tell.  Close enough for me since I never want to get close to needing more accuracy.

I think you’ll find that your gages aren’t going to read very well even with accurate senders.  And cies senders won’t work with those gages anyway.

I should probably get both sides overhauled and then dip stick them to see if they perform similarly.  Been focusing on the left which was getting wacky.  I think part of the issue with the F is they have the two senders on each tank wired in series (if I remember correctly; not an expert).  Seems like I remember the gauges getting a little bouncy too when the outboard sender is near the bottom of it's arc.  

[Ragsf15e]

13 minutes ago, DCarlton said:

I should probably get both sides overhauled and then dip stick them to see if they perform similarly.  Been focusing on the left which was getting wacky.  I think part of the issue with the F is they have the two senders on each tank wired in series (if I remember correctly; not an expert).  Seems like I remember the gauges getting a little bouncy too when the outboard sender is near the bottom of it's arc.  

Agree.  I have had the outboard one stick once or twice after refueling and only indicate about 15 gallons.  Taxing over a few small bumps and it unstuck.  Never had any issues getting accurate readings in flight.

Do you have ff and a totalizer?  Having that to compare to gages is really helpful.  2 separate accounts of your fuel state.

[ArtVandelay]

The new firmware also has some quirks that still continue to annoy me.

Can you elaborate?

[Utah20Gflyer]

I upgraded to the CIES senders and an aerospace logic fuel gauge at the beginning of the year.  After making the upgrade I wouldn’t ever want to go back.  I get the desire to save money but this is an area I wouldn’t choose to skimp.   
 

I created my own calibrated dipstick by emptying a tank and adding 1 gallon at a time and creating a chart based on the measurements. 

[ArtVandelay]

Do you have ff and a totalizer?  Having that to compare to gages is really helpful.  2 separate accounts of your fuel state.

And if you have the wing gauges that gives you 3.
FF is the most accurate.
I overhauled because I have 4 senders and only the inboard ones needed it.

[DCarlton]

2 hours ago, Ragsf15e said:

Agree.  I have had the outboard one stick once or twice after refueling and only indicate about 15 gallons.  Taxing over a few small bumps and it unstuck.  Never had any issues getting accurate readings in flight.

Do you have ff and a totalizer?  Having that to compare to gages is really helpful.  2 separate accounts of your fuel state.

Negative.

[MikeOH]

Heretical, I know, but I really have no desire to spend the bucks for the CIES; heck, I barely even look at the factory gauges.  I was taught to fly by fuel flow (power setting) and time, and stick the tanks before flight.  I do have a FF/totalizer which I like but, again, don't trust to be unerring.  On typical 50 gallon fill ups it's within 1-2 gallons; about 4% and that may be due to differing ramp locations.

I only use those gauges (ship's and FF) to verify something bad isn't happening, not to fly to the last gallon before reserve.

Another way to weigh this is look at the improvement in accuracy.  Are you going to trust the CIES to better than 1%?  Not likely, so you have a, maybe, 3% improvement in accuracy (from the 4% FF/totalizer).  On 64 gallon tanks, that's 2 gallons more "you can count on". At 10 gph, that's an extra 12 minutes.

I really try not to put myself in a position where I need another 12 minutes of fuel

[rwabdu]

1 hour ago, MikeOH said:

Heretical, I know, but I really have no desire to spend the bucks for the CIES; heck, I barely even look at the factory gauges.  I was taught to fly by fuel flow (power setting) and time, and stick the tanks before flight.  I do have a FF/totalizer which I like but, again, don't trust to be unerring.  On typical 50 gallon fill ups it's within 1-2 gallons; about 4% and that may be due to differing ramp locations.

I only use those gauges (ship's and FF) to verify something bad isn't happening, not to fly to the last gallon before reserve.

Another way to weigh this is look at the improvement in accuracy.  Are you going to trust the CIES to better than 1%?  Not likely, so you have a, maybe, 3% improvement in accuracy (from the 4% FF/totalizer).  On 64 gallon tanks, that's 2 gallons more "you can count on". At 10 gph, that's an extra 12 minutes.

I really try not to put myself in a position where I need another 12 minutes of fuel

All makes a lot of sense. Seems like if I can cheaply overhaul the current senders I'll just do that unless I could get the CIES gauges for less than 1AMU which doesn't seem possible. Maybe go for the CIES when more disposable income. 

I currently have a JPI with fuel flow which I use to verify my fuel burn. Only things I can't account for is if my tank were to leak without me knowing or if the FBO is careless about how full they get my tanks. I recently almost took off with 12 gal less than expected because the FBO was carless about filling my tanks all the way up. I always look in the tank before going, it didn't look full. I asked them come back and fill the rest of the way up, added 12 gal to my 54 gal tanks before departing on a 370mi cross country.... Next free day I had I emptied a tank and filled it back up 5 gal at a time and marked out a dip stick. Emptying the tank is also what confirmed my factory gauges were bad. Next time I'm at the hangar, I can take a picture of my fuel stick next to a ruler if anyone wants to try to replicate it without having to empty a tank. 

Really appreciate the opinions. 

Edited October 29, 2022 by rwabdu

[MikeOH]

You don't have to empty your tanks to make a fuel stick; just a little fuel showing at the bottom is what I did.  Dip, mark that level, then fill and mark at whatever interval you like (doesn't even have to be the same interval amounts as long as you keep track). When filled to the brim, that's 32 gallons (or whatever full for your plane is), then subtract your interval amounts and mark the stick accordingly.  True, you can't know the amount if the tanks have less than the starting point.  But that's going to be in the 5-8 gallon range.

[FlyingDude]

Try owner-building a sender using 1940s Chevy truck sender. It's the same thing...

[ArtVandelay]

Try owner-building a sender using 1940s Chevy truck sender. It's the same thing...

Same armatures?

[FlyingDude]

4 hours ago, ArtVandelay said:

Same armatures?

They used to have the exact same item. Now, suppliers combined 2 part numbers so now the floats are different. Brass versus plastic. Your mech can swap the armatures.

this is the correct part number. But note that it says brass float in the description:

https://www.streetrodhq.com/detail/30031/Chevrolet_Gas_Tank_Sending_Unit_030_Ohms_For_Gas_Gauge_6V_Or.html

so you end up getting this:

https://www.chevsofthe40s.com/detail/42209/Gas_Tank_Sending_Unit_030_Ohms_For_Gas_Gauge_6V_Or.html

no biggie for a good mechanic...

 

[S.C.]

I tried getting the old ones overhauled in my C.  Paid a few hundred dollars, put them back in and they still were jumpy and inaccurate.  It was frustrating. 
 

I put the EDM 900 in, it was better, but the old senders were still telling the same inaccurate story. 
 

Last year, I had the tanks resealed and put in the CiES.  Now I am very confident that the gauges are accurate. EDM reset was not too bad, they were very helpful and worked directly with my mechanic.  I still fly by timing the fuel but know that now the indicators in the cockpit are matching the math on my flight plan. 
 

I recommend going all in and not doing it piece meal if you can afford to do it now.  Upgrades are a more expensive up front but less stress and recurrent headaches in the long run.  
 

 

[jlunseth]

I put in the CiES senders and they were an improvement, but I did not find them to be the miracle workers they are sometimes portrayed to be. They connect to my JPI930. I still don’t rely on tank gauges. I rely on knowing how much is in each tank at the start of a flight less fuel flow from each tank. I tested the fuel flow readout for accuracy quite a few years ago, it was accurate too .1 gallon out of 50 gallons used. Probably should test it again, but my aircraft has so much endurance, especially at LOP, that fuel is really a non-issue on the vast majority of flights, but when it is, I would not rely on the gauges for anything except a general indication of what is in each tank.

[ArtVandelay]

BTW, senders can work great with analog but not with digital gauges because the readings aren’t consistent. You can manually check this using ohmmeter and verifying readings are stable and consistent as you move the armatures.

[DCarlton]

19 hours ago, rwabdu said:

All makes a lot of sense. Seems like if I can cheaply overhaul the current senders I'll just do that unless I could get the CIES gauges for less than 1AMU which doesn't seem possible. Maybe go for the CIES when more disposable income. 

I currently have a JPI with fuel flow which I use to verify my fuel burn. Only things I can't account for is if my tank were to leak without me knowing or if the FBO is careless about how full they get my tanks. I recently almost took off with 12 gal less than expected because the FBO was carless about filling my tanks all the way up. I always look in the tank before going, it didn't look full. I asked them come back and fill the rest of the way up, added 12 gal to my 54 gal tanks before departing on a 370mi cross country.... Next free day I had I emptied a tank and filled it back up 5 gal at a time and marked out a dip stick. Emptying the tank is also what confirmed my factory gauges were bad. Next time I'm at the hangar, I can take a picture of my fuel stick next to a ruler if anyone wants to try to replicate it without having to empty a tank. 

Really appreciate the opinions. 

The one fuel related failure mode I have swirling in my head that I worry about is....  what happens if the fuel sump drain valve doesn't seat properly and you drain both tanks in flight?  I've always wondered if that is possible.  During my preflight, I pull the valve, let it drain for a few seconds, push it down deliberately, and then walk around to the left side of the plane to make sure it's no longer dripping.  Fuel gauges might help you spot that sort of failure before you're dry.  Wondering if anyone has experience with that drain valve not reseating properly and failing open ?  I've never seen the guts to know how it works.