Fuel senders

[fallguy]

I have 2 Moeller FT64 tanks with 13” arm senders.

they are terrible and are ranging from 0-9 gallons error

On a recent voyage, I departed a marina and the gauges reported zero on one tank and I returned to port about 8 miles on one engine and once in port harbor; the gauge reading went to 9 gallons and was reading 0-3 the entire return trip.

I want advice about the best way to go for new senders. There are a few different kinds. My current senders are analog and I have Yacht Devices a/d converters which may also be contributing to errors.

And do I need to empty my tanks for the new work or do I take a stick measurement for calibration?

A bit nervous about fuel vapors/explosion, but I’ll be careful.

 

[kapnD]

I developed a well earned mistrust of fuel measurement gauges early on, and learned not to rely on them.
Get to know your crafts fuel consumption habits, and you will always have a surprisingly close tally in your head of how much fuel is remaining in your tank.
That stick is your best friend!

 

[Barry]

I have 2 Moeller FT64 tanks with 13” arm senders.

they are terrible and are ranging from 0-9 gallons error

On a recent voyage, I departed a marina and the gauges reported zero on one tank and I returned to port about 8 miles on one engine and once in port harbor; the gauge reading went to 9 gallons and was reading 0-3 the entire return trip.

I want advice about the best way to go for new senders. There are a few different kinds. My current senders are analog and I have Yacht Devices a/d converters which may also be contributing to errors.

And do I need to empty my tanks for the new work or do I take a stick measurement for calibration?

A bit nervous about fuel vapors/explosion, but I’ll be careful.

Contact a Moeller dealer and buy direct replacements

Not all guages work with all senders.

There are polarity differences as well as postive and negative ohm ranges.

 

[Darkzillicon]

You could also contact yacht device manufacturers and inquire about calibrating their digital readouts to the new gauges. I would recommend this approach as analog senders are likely the most cost-effective option Regarding simplicity, am aware that Blue Sea Systems used to offer ultrasonic fuel tank senders, should be fairly accurate and foolproof, albeit more expensive. Best of luck with your search!

 

[BlueBell]

Fuel senders are horrible, terrible things.
A dipstick is the most accurate fuel measuring device I have ever seen.
Almost foolproof.

 

[Ithaka]

I also have un unkown 40 year old sender and the YD A/D converter. I agree it is difficult to work with, the fuel is sloshing around and giving errorneous reading. My best advice is to measure the resistance when you add fuel (if you have two tanks and are half empty, you can just transfer fuel from one tank to the other and back with a transfer pump). Measure the resistance of the sender a couple of times, from min to max, extrapolate when necessary, then calculate the curves and input in your A/D parameter file. This still has a train of measurement errors (the gauge on the transfer pump, the geometry of the tanks, the approximation, etc.). Make the time averaging constant of the A/D converter longish (say 10-15 seconds at least). That would be as good as it gets. You really do not need much more accuracy. The next level is to go for fuel flow metering, there are inexpensive solutions there but it brings other problems.

 

[fallguy]

I purchased two Maretron fuel senders with float tubes. I still have to determine the line distances and see if I have any n2K cables long enough.

I also have to cut off the float tubes and epoxy them and configure the devices with existing fuel in the tanks. The cost of the system was almost $450 a tank, so some sticker shock for me, but hoping for stable readings.

 

[Barry]

Ohms / Resistance (Empty - Full)

Popular Models
Most GM cars, 1965 to Present 0 - 90 Ohms
Ford models (prior to 1989) and most Chrysler models. 73 - 10 Ohms
Industry Standard. Works with many popular models. 240 - 33.5 Ohms
Most GM models, prior to 1965 0 - 30 Ohms
Most Ford models, 1989 and Newer. 6 - 158 Ohms

I had mentioned in an earlier post that senders have to be matched to the gauge. The above list is some of the current ranges. I am not sure if the marine industry has something different

An update from a marine site.
The standard ohm range for a marine fuel tank sender in the US is typically 240 ohms at empty and 33 ohms at full. In Europe, a common standard is 0 ohms at empty and 180 ohms at full.


American Standard (240-33 ohms):

• Empty: The sender will read between 232 and 252 ohms when the tank is empty.
• Full: The sender will read between 28 and 36 ohms when the tank is full.

 

[Darkzillicon]

I purchased two Maretron fuel senders with float tubes. I still have to determine the line distances and see if I have any n2K cables long enough.

I also have to cut off the float tubes and epoxy them and configure the devices with existing fuel in the tanks. The cost of the system was almost $450 a tank, so some sticker shock for me, but hoping for stable readings.

Yea Maretron makes great stuff but i think blue sea systems makes an ultrasonic one but you have to use their proprietary gauge that's like a bilge counter and other things. but i think you're limited to depth of 32" or less. Might be less money but ive heard the ultrasonic senders are less sloshy

Best of luck!

 

[Barry]

I purchased two Maretron fuel senders with float tubes. I still have to determine the line distances and see if I have any n2K cables long enough.

I also have to cut off the float tubes and epoxy them and configure the devices with existing fuel in the tanks. The cost of the system was almost $450 a tank, so some sticker shock for me, but hoping for stable readings.

Just remembered a small but important point
The gasket has to be a rubber (not sure if neoprene, ABS etc) as compared to the cork and rubber combination that often comes with automotive style senders. As they are Maretron, they are probably all rubber