The Hull Truth - Boating and Fishing Forum

The Hull Truth - Boating and Fishing Forum (https://www.thehulltruth.com/index.php)
-   Marine Electronics Forum (https://www.thehulltruth.com/marine-electronics-forum-19/)
-   -   Managing fuel quantity? (https://www.thehulltruth.com/marine-electronics-forum/896140-managing-fuel-quantity.html)

stephenson 12-08-2017 06:12 AM

Managing fuel quantity?
 
So, am getting new boat with 250 Yamaha, but without Yamah gauges ...clean console except for switches and CB panel.

Looks like straightforward install of 8xx Garmin MFD, but I hadn't even considered how to monitor total fuel in the tank ...looks like the broad process of knowing how much fuel in the tank relates to a full starting point, resetting the fuel management software on the MFD each time you refuel to Full, then the MFD takes burn rate from the motor (with time factor), and subtracts that number from the total fuel added (based on number of gallons setting you put into the MFD for "Full."

Some folks report they added a Lowrance (Navico) Fuel Data Manager as an interface - Simrad shows the same part ...looks like a common part. This device apparently stores the burn rates and maintains the data all th tim, whereas some MFDs will only compute but not store the data?

Is this needed in all setups, or just certain MFDs?

Here's what Navico says about the device:

"Navico Fuel Data Manager

Monitors Fuel Rate/Fuel Flow from NMEA 2000 engines, and accumulates Fuel Rate into Fuel Used. Outputs seasonal, trip and total fuel used.

Features
Replaces EP-85
Monitors Fuel Rate/Fuel Flow from NMEA 2000 engines, and accumulates Fuel Rate into Fuel Used
Outputs: Seasonal/Trip/Total Fuel Used
Will report accurate Vessel Fuel Remaining if MFD Fuel screen is maintained at every refuel
One sensor will monitor up to 3 engines
Additional Fuel Data Managers can be added for more engines
Will monitor fuel rates from multiple engines transmitting through a single gateway

Manufacturer Part Number: 000-11522-001

Fwpratt 12-08-2017 06:29 AM

1 Attachment(s)
your Garmin requires nothing more than the NMEA 2000 input from the yamaha -

(why Navico requires (continues to?) a separate module is beyond me)

Using the Garmin "virtual" fuel gauge - "Total Fuel Onboard"-
rather than an actual N2K fuel tank level sensor input (which is an alternative)

you will at any time have three options:


Attachment 1026036


I use the Garmin function, and find the Yamaha input very accurate.

However, I would not be comfortable without a "second opinion";
I also have a WEMA tank sender and analog VDO gauge -
which, motionless at the dock, is repeatable/accurate/precise to well within 5 gallons

rickboat 12-08-2017 06:33 AM

Correct, but I've found you have to indicate the change in fuel and then keep the switch on (or use the boat) for some period of time (unknown). If I turn the key on, hit Fill Up All Tanks or Add Fuel to Boat, and then turn the key off, the setting is lost. But if I fill up, start the engine, and then do it and go for a ride, it's fine. Don't know what length of "On Time" is required.

arich 12-08-2017 07:11 AM

After a few cycles you gauge how accurate it is. Mine are about 10 gallons off in each tank after burning 120-130 gallons per engine. So if my computer tells my I've burned 260 total gallons on a trip each tank will only take 120 to fill to the top. Caught me off guard a couple times with the high flow fills. Now I slow down when I'm ten gallons away from what I think will be full and slowly top it off to avoid overfilling and making a mess.
Ant

smac999 12-08-2017 01:26 PM

get a tank sensor and always know the exact amount. I wouldn't trust a calculation on how much you've used and how much is left.

Marshfly 12-09-2017 06:32 AM


Originally Posted by smac999 (Post 10909403)
get a tank sensor and always know the exact amount. I wouldn't trust a calculation on how much you've used and how much is left.

The engine knows exactly how much fuel is being run through the throttle body on modern fuel injected outboards. My last three Yamaha setups have been within a quarter gallon on every single fillup and I can attribute that difference to changes in the way I pump and the slope of the concrete at the service station. A buddy with an Evinrude G2 sees the same level of accuracy.

These aren't estimates. This is the engine computer telling exactly how much fuel it is metering into the injectors.

Fwpratt 12-09-2017 06:44 AM


Originally Posted by Marshfly (Post 10910997)
These aren't estimates. This is the engine computer telling exactly how much fuel it is metering into the injectors.

well, on the Yamaha, its the ECU reporting how much fuel should be flowing
a "calculation" of rpm X injector actuation time

- assuming the rail pressure is as designed
- assuming the injectors are 100% clean, and opening/closing as designed

none of which is actually verifiable by the ECU

but it certainly can be extremely accurate

stephenson 12-09-2017 07:23 AM

Hmmmm ...

FWP - I thought measurement was based on the amount of air being sucked past the MAF, and then the fuel usage extrapolated from the fuel injected data table ... my understanding is that the airflow sensor (MAF) is extremely accurate, so, even though the fuel usage is related, it isn't actually measured.

In summary, then:
- readout on the "gas gauge" whether analog or digital is pretty much a resistance based summary based on a float or liquid level in the tank with commensurate errors based on tank size estimates, float or resistance errors, length of the bar measuring resistance, etc.
- readout of fuel used (or remaining as computed by the MFD) on from the engine is based on much more accurate process of measuring the actual amount of fuel (or, air and extrapolating fuel) used by the engine, but knowing the amount remaining does require resetting the MFD or gauges each fill up to full (Marshfly's experience is pretty typical and reported widely)

Both sources is a good idea ...however, to me it makes sense to hide the resistance reading gauge because it is now more of a backup - with much lower accuracy - ASSUMING the gauges/MFD are reset each fill up.

pmgia 12-09-2017 10:00 PM

I have a Suzuki connected to the NEMA2000 network and it alone is super. I also have the Simrad Fluid Level Sensor analog to NEMA2000 device that my fuel tank sensor is connected to and it works great.

When I fill up these are within 0.2 gallons consistently.

If you go Offshore I recommend both!

With my setup I calculate fuel two ways and both are displayed on my Simrad evo2. I have the amount in the tank from the sensor and also what Suzuki says is my fuel burned since fill up subtracted from a full tank, compare those amounts to fuel added as a double check and I’m confident I’ll never run out of fuel.

If you stay inshore one way might be ok, but Offshore I like having two methods to determine my fuel on board and I display both on my MFD all the time.

stephenson 12-10-2017 06:04 AM

4 Attachment(s)
pmgia,

I think what you are talking about is this two wire to NMEA connector? http://www.simrad-yachting.com/en-US...sor-en-us.aspx. Photo shows the two wire connector to NMEA 2000 connector.

Did you install it yourself? What does it show on your MFD - a bar graph of some sort? I would not think it would be able to display quantity very accurately since the basic analog signal from the sending unit it just a converted resistance reading ...not sure how it could compare to 0.2 gallons given this type of signal.

If, however you are talking about the Simrad E85 Fuel Data Manager at http://www.simrad-yachting.com/en-US...a-Manager.aspx, then it reads like it is doing the same thing your MFD is doing - i.e. receiving the continual fuel burned readings from the engine computer and saving and then displaying them - sounds like it may also be saving these readings. Do you have to reset it, as well, when you refuel? Photo shows an NMEA 2000 connected and powered device that saves engine fuel burn data.

pmgia 12-10-2017 08:53 AM

You are correct, I will fix my earlier post, I am using the Fluid Level Sensor, it is within 0.2 gallons when I fill up my tank. For example,
Assume 100g tank
Fluid level will show 50.2 gallons remaining
Suzuki full less burn will show 50.0 gallons remaining
I will fill the tank and it will take 49.8 or 50.1 gallons of fuel. I always tell the guy at the dock how much I think I'll take in fuel and he's usually amazed I know within a 1/4 gallon.

I did install the Fluid Level Sensor myself, on the setup in my Simrad I had to put the size of tank and I selected the maximum number of points in the tank, I think it was 5. I then filled the tank, told the equipment it was full and the first 3-4 times I fueled up I told the system how many gallons I added, not its very accurate.

My Fluid Level Sensor display shows XX.X in numbers and it varies when on plane accelerating or slowing but when the boat is sitting in calm water the Fluid Level Sensor reading and the Suzuki full minus used is within 0.2 on average. The fuel calculation that Suzuki makes doesn't fluctuate on during accelerating or slowing and I would trust the engine computer accuracy over the fluid level, new engines and their onboard computers know exactly what they burn.

stephenson 12-10-2017 09:23 AM

pmgia,

That is pretty remarkable fuel tank sending unit ... is it a resistance type? Float or straight?

Usually these things are within about 1/4 tank :-). If they are more accurate with NMEA connection to an MFD, it may mean the MFD interprets the resistance reading better - or, more accurately - interesting!!

So, back to the NMEA install - after a bit more looking, the connector cable is a standard Navico product - another $100 cable ... sigh. Looks pretty straightforward.

This has been helpful - now means I don't need a separate fuel gauge - assuming two MFDs, there is always a backup device able to display the information. Waaaay better than drilling a round hole somewhere to make me feel good! Shoot, $100 may be cheaper than having someone drill the hole and connect the wires to it ... :-)

Thanks!

arich 12-10-2017 03:11 PM


Originally Posted by stephenson (Post 10913200)
pmgia,

I think what you are talking about is this two wire to NMEA connector? http://www.simrad-yachting.com/en-US...sor-en-us.aspx. Photo shows the two wire connector to NMEA 2000 connector.

Did you install it yourself? What does it show on your MFD - a bar graph of some sort? I would not think it would be able to display quantity very accurately since the basic analog signal from the sending unit it just a converted resistance reading ...not sure how it could compare to 0.2 gallons given this type of signal.

If, however you are talking about the Simrad E85 Fuel Data Manager at http://www.simrad-yachting.com/en-US...a-Manager.aspx, then it reads like it is doing the same thing your MFD is doing - i.e. receiving the continual fuel burned readings from the engine computer and saving and then displaying them - sounds like it may also be saving these readings. Do you have to reset it, as well, when you refuel? Photo shows an NMEA 2000 connected and powered device that saves engine fuel burn data.


Going to order two of those, Thanks

norton79 12-11-2017 04:48 AM

I also have a fluid level sender connected to a wemma tank sender and have very accurate level readings. I agree that if going off shore you need more then just the computer readout for fuel remaining. Can the computer tell you if there is a fuel leak and there is now only 1/4 tank when there should be 1/2?

stephenson 12-11-2017 07:58 AM

norton79,

Which of the Wema sending units do you have ... looks like they make several varieties - all are resistance based, I think....?

http://www.wemausa.com

Onewolf 12-11-2017 08:09 AM


Originally Posted by Marshfly (Post 10910997)
The engine knows exactly how much fuel is being run through the throttle body on modern fuel injected outboards. My last three Yamaha setups have been within a quarter gallon on every single fillup and I can attribute that difference to changes in the way I pump and the slope of the concrete at the service station. A buddy with an Evinrude G2 sees the same level of accuracy.

These aren't estimates. This is the engine computer telling exactly how much fuel it is metering into the injectors.

Do they know if some thief has siphoned/drained fuel out of your tank? :grin:

stephenson 12-11-2017 10:44 AM

Fixed my post - Wema, not Woman .,... :-)

norton79 12-12-2017 05:53 AM

Im not 100 percent on the exact unit but can look it up on the weekend. Yes it is a resistive type and you need to get the right resistance. One type as fuel level drops resistance will drop and the other resistance will raise. You just need to follow the instructions in the ep60r or ep65r. Cannot remember with one it is. I have a older outboard and use both for flow and level. If i fill my 40lt tank and run out and use 18lts i expect to see just over half a tank level. If i see less i start to look for problems eg leaks

Marshfly 12-12-2017 06:18 AM


Originally Posted by Onewolf (Post 10916022)
Do they know if some thief has siphoned/drained fuel out of your tank? :grin:

My boat sleeps in a garage so that's not an issue. A quick look at the fuel level gauge would tell me that however. And they make keyed gas fills if your boat has to stay outside. No way in hell would I really on a tank level gauge to accurately tell me how much fuel I've burned to the tenth of a gallon. I can reliably do that with the total fuel used on the Yamaha gauge because I've tested it through dozens of fillups under very differing usage conditions.

You have to test whatever method you are using to know how much fuel you are using so that you know without a doubt that it is accurate. On my EC Caimen it was a wooden stick stuck in the tank. On my Maverick HPXV and my YF21 it's the Yamaha gauge.

Arguing about differing methods on different boats is dumb. You have to test YOUR method on YOUR boat and if it isn't sufficient for your use, figure something else out. For my use, the the factory Yamaha gauge gives me enough accuracy to run multiple trips without refilling the tank knowing that it will remain accurate. Then I verify at the pump when I reset it.

Onewolf 12-12-2017 06:24 AM


Originally Posted by Marshfly (Post 10918912)
My boat sleeps in a garage so that's not an issue. A quick look at the fuel level gauge would tell me that however. And they make keyed gas fills if your boat has to stay outside. No way in hell would I really on a tank level gauge to accurately tell me how much fuel I've burned to the tenth of a gallon. I can reliably do that with the total fuel used on the Yamaha gauge because I've tested it through dozens of fillups under very differing usage conditions.

You have to test whatever method you are using to know how much fuel you are using so that you know without a doubt that it is accurate. On my EC Caimen it was a wooden stick stuck in the tank. On my Maverick HPXV and my YF21 it's the Yamaha gauge.

Arguing about differing methods on different boats is dumb. You have to test YOUR method on YOUR boat and if it isn't sufficient for your use, figure something else out. For my use, the the factory Yamaha gauge gives me enough accuracy to run multiple trips without refilling the tank knowing that it will remain accurate. Then I verify at the pump when I reset it.

I'm sorry, I thought you were saying that a classic fuel gauge was not necessary because the ECU fuel metering was so accurate.


All times are GMT -7. The time now is 07:51 PM.

Powered by vBulletin® Version 3.9.3.7
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.
Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.