Fuel sender and gauge info

[fred1diver]

Hello again.
I would like to install a fuel sensor(?) to
My monel gas tank, how do I do that? Is is at all possible to do to start?

 

[FastOlson]

We have a "WEMA" fuel tank sensor mounted on the top of our aluminum tank, wired to a panel gauge. Seems to work fine for well over a decade. You would have to drain the tank and drill a hole in the top. Lots of web links, and I do not know who is reputable. Here is just one: FUEL TANK GAUGE METER AND SENDER 7-1/2" STAINLESS WEMA KUS CPFR-WW-240

 

[fred1diver]

Thank you, I should have specified that my tank is round, that unit looks great but I don’t know if I could mount it on a round tank?

 

[Stu Jackson]

Fred, in tank fuel senders are notoriously unreliable, failing often, and requiring replacement. The most important number you need to know is your fuel consumption in gallons per hour of engine run time. Knowing your fuel tank capacity will tell when you need to refill. If you don't have an engine hour meter, then installing one is way easier than a fuel sender and gauge.

 

[Tally Ho]

Do you have sort of sight gauge on the tank now? Specifically something that looks like this…



It would be mounted on the top of the tank somewhere (and it wouldn’t have a wire attached).

My O’Day 322 came with this visual gauge that was impossible to see (tank is below the floor in the lazzarette). As I researched this, someone told me that the visual gauge would also drive a fuel gauge. I was not to optimistic that was true, but found out that the Moeller sender and visual gauge would in fact connect to a fuel gauge. So I bought one for the right ohm range, hooked up a few wires (need power, a ground and the ohm wire from the little sight gauge). And boom! I have a working fuel gauge where I can readily see it.



Greg

 

[kappykaplan]

The most important number you need to know is your fuel consumption in gallons per hour of engine run time. Knowing your fuel tank capacity will tell when you need to refill.

 

[jssailem]

I agree with Stu on fuel consumption management.

That said, it is nice to have a glimpse at a gauge to support my math and calculations.

I use the same WEMA sensor shown by @FastOlson on my 85-gallon tank
I have also used a dip stick to estimate the volume of fuel in the tank when I question the sensor or have misplaced the fuel log and need to add fuel to the tank.

Many options exist. If you can drill a hole in your round tank, you can install an internal fuel sensor.

 

[Tally Ho]

Fred, in tank fuel senders The most important number you need to know is your fuel consumption in gallons per hour of engine run time. Knowing your fuel tank capacity will tell when you need to refill. If you don't have an engine hour meter, then installing one is way easier than a fuel sender and gauge.

I don’t disagree that you can calculate fuel usage (and therefor remaining fuel), but it isn’t convenient. I religiously write down my engine hours in my log, but I don’t total them up every day…so to determine where I am in the tank, I would have to sit down and add them all up (I motor about .3 to .5 hours per trip…so that is a lot of dates to add up).

Like @jssailem said, very convenient to have a fuel gauge. At least it lets me know when I am at a quarter tank, and I will either fill up or start carrying a Jerry can if for some reason I don’t want to fill the tank right away.

But just my preference.

Greg

 

[Stu Jackson]

), but it isn’t convenient.

I completely disagree.

I made a spreadsheet, and it is not any inconvenience to update it once every few months. It even predicts how much fuel I need next time!

Fuel Log 101

Fuel Log

 

[dlochner]

With a round tank, the problem having a small penetration that is easily sealed. Most sensors require bigger holes and footprints making sealing the hole difficult to impossible. On a metal tank external sensors are not a possibility.

There is one tank monitor that uses air pressure and has a small fitting that may work, Tank Tender. Take a look.

Home -

The original precision tank measuring system. One instrument measures from 1 to 10 tanks. It gauges the liquid level in water, diesel & holding tanks.

tanktender.com

 

[Tally Ho]

I made a spreadsheet…update it once every few months.

My definition of ”inconvenient”.

Greg

 

[Tally Ho]

With a round tank, the problem having a small penetration that is easily sealed. Most sensors require bigger holes and footprints making sealing the hole difficult to impossible. On a metal tank external sensors are not a possibility.

There is one tank monitor that uses air pressure and has a small fitting that may work, Tank Tender. Take a look.

Home -

The original precision tank measuring system. One instrument measures from 1 to 10 tanks. It gauges the liquid level in water, diesel & holding tanks.

tanktender.com

Is it ‘round’ as in a sphere…or a round cylinder? Which would have a flat top and bottom?


Greg

 

[fred1diver]

Think of it as a metal drum
On it’s side

 

[Stu Jackson]

Aha, fred. Then you must be aware that a float type sender will not give you much useful information on a gauge, because they are linear based on fuel depth, not actual fuel volume. Fuel consumption based on engine hours is still your best bet, and costs nothing, except for that pesky few minutes to note it down and use the spreadsheet that has Greg so distraught.

 

[MikeHoncho]

I installed a sending unit in my tank which had a single access point (outside of the fill neck). It was easy to install, you just need to make sure you account for the vent access. I ordered mine with a vent port in it. I wired it to not be energized all the time with a rocker switch below it. This saves on energy as I don't need a gauge on all the time. I can see my level through my tank (poly) by accessing the lazarette but having a gauge in the cabin has had some convenience. I read it as "full'ish, half'ish and I need to fuel up"

 

[dlochner]

Check out Gobius senders. They may have something that will work on a cylinder tank. You may have to calibrate any tank sender manually, i.e, pour in 5 gallons, see what the sender says, and so forth.

Regardless of contrary opinions, knowing your burn rate and the engine hours is important if you do any long distance motoring. If you are one who mostly day sails and fills their tank once a season, then this is less important.

 

[Stu Jackson]

I read it as "full'ish, half'ish and I need to fuel up"

Good points based on even purely rectangular tanks.

If you are one who mostly day sails and fills their tank once a season, then this is less important.

Very true, and important to understand.
However, ALL of us have and have to have fuel tank vents. Many of them drain overboard and require careful observation and/or control, to avoid dumping overflow fuel into the water. The true beauty of KNOWING how much fuel you need on your next refill is that one ends up STOPPING the fuel fill BEFORE it overflows. I fuel up with "I need 12.5 gallons and slow way down well before I get there - no vent drips," NOT "I think I need around 13 gallons and fill til it overflows." OK, I know most of you don't do that, but how often do we see questions on this and other boating forums about overfills and dribbling diesel from vents. Even with a gauge it doesn't hurt to know and keep track. Because one day your gauge sender WILL die, and you'll be disappointed you didn't keep track when It could've cost you nothing,

 

[MikeHoncho]

Good points based on even purely rectangular tanks.

Very true, and important to understand.
However, ALL of us have and have to have fuel tank vents. Many of them drain overboard and require careful observation and/or control, to avoid dumping overflow fuel into the water. The true beauty of KNOWING how much fuel you need on your next refill is that one ends up STOPPING the fuel fill BEFORE it overflows. I fuel up with "I need 12.5 gallons and slow way down well before I get there - no vent drips," NOT "I think I need around 13 gallons and fill til it overflows." OK, I know most of you don't do that, but how often do we see questions on this and other boating forums about overfills and dribbling diesel from vents. Even with a gauge it doesn't hurt to know and keep track. Because one day your gauge sender WILL die, and you'll be disappointed you didn't keep track when It could've cost you nothing,

I have a visual on my tank as I'm filling and can see the level. My previous was aluminum and with that, I'd agree.