Garmin Fuel Monitoring

I have a Garmin 740S Chartplotter which has the ability to monitor fuel, however Garmin's fuel monitoring device only works with Gasoline and any respecting trawler owner run the diesel stuff. Has any one had success or investigated using the NMEA 2000 connection on a Garmin for fuel monitoring and what meter do you use?

Garmin GFS 10 Fuel Sensor

I talked to Flowscan. it would cost about $700.00 bucks for an interface for the nema 2000. Then it would work.

Do you currently have a fuel flow monitor?

Sd

SD,

Thanks, I don't have one now and with a LH120 not sure I really need one, but would like it. $700 holy smokes, Flowscan is so expensive but I understand very good

David

I looked into it because the garmin I have, has the dash board gages on one of the screens.
When I thought about it was not much of an issue just to look at the Flow Scan.
It has a tac with a gph and an hour meter as well as a total fuel used
the interface is A nice option but not really worth the cost to me that is

SD

How much was the self contained flowscan system?

Maretron also have a solution....which was recently favourably reviewed in PassageMaker and seen as being superior to FlowScan. It is also cheaper and has recently taken out an industry award. Details: Maretron : Marine Electronic Instruments

When I bought mine I don't remember.
Google Flow Scan.
Give them a call. Nice people.

SD

however Garmin's fuel monitoring device only works with Gasoline

The gas flow meters only count the fuel going to the engine.

A diesel requires a return flow meter , and the unit counts the difference.

However not all diesels have a return flow that matters very much.

Usually the Bosch style does not return a lot , but its individual , A VW diesel is like a DD , the return is huge.

Perhaps a measure to find the return volume on your engine , might be the place to start to see if the gas unit would work?

FF

As nice as it would be to monitor fuel use on my boat, it appears that it would cost nearly $1K. My fuel use for the four years I have owned my boat has averaged less than $1K per year.

Saving 10% in fuel use by monitoring it would take more than ten years before the savings would pay for the system. I don't think it's a wise investment for me.

Rwidman, you make very valid points. I think I'll run the boat for an hour at a time at different rpms and record fuel level. We travel to and from Catalina island here in California. So I could easily judge fuel use in that regard. Thanks for the advice and input all.

patzfan4eva said:

Rwidman, you make very valid points. I think I'll run the boat for an hour at a time at different rpms and record fuel level. We travel to and from Catalina island here in California. So I could easily judge fuel use in that regard. Thanks for the advice and input all.

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For many fuel management systems are more about fuel usage than savings...especially because the average fuel tank monitor for boats are often so inaccurate or unreliable.

Many feel because of the total tankage, sight guages, and low consumption...you would have to be pretty incompetent to run out of fuel in a trawler while coastal cruising.

Usually once you get an accurate fuel usage on a small diesel...however you choose to do it...guestimations from there on are pretty accurate.

patzfan4eva said:

SD,

Thanks, I don't have one now and with a LH120 not sure I really need one, but would like it. $700 holy smokes, Flowscan is so expensive but I understand very good

David

Click to expand...

The 120 Lehman, 2715, returns somewhere around a pint in 8 hours at full throttle. The Garmin unit would work just fine.

From Garmin....

"The plastic the GFS 10 is made of will deteriorate with diesel fuel. NMEA 2000 is an industry standard so a Diesel sensor from another manufacturer can be used."

Interesting diesel would eat it and gas wouldn't. I wonder what the time frame is ?

Vyndance said:

Interesting diesel would eat it and gas wouldn't. I wonder what the time frame is ?

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It does seem at odds with most of the chemical resistance charts. PBT is given an "A" grade for diesel fuel resistance by these guys while they give it a "B" for gasoline.

Several sources give PBT a good compatibility rating with diesel. Maybe the manufacturer is just trying to discourage people from using these on a diesel so they will by a more expensive system.

Pressing them again, now the answer is that the wheel on the inside won't read the diesel fuel correctly. There's gotta be more to this story...but I'm done trying to figure out what. LOL!

patzfan4eva said:

Pressing them again, now the answer is that the wheel on the inside won't read the diesel fuel correctly. There's gotta be more to this story...but I'm done trying to figure out what. LOL!

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There really isn't much more to it than they want you to buy their more expensive system.

Turbine and paddlewheel flow meters of the kind they use will work over a reasonably wide range of viscosity that includes gas and diesel.

If you want to homebrew a system, look on the net for automotive fuel flow meters for an inexpensive turbine or paddlewheel meter with a pulse or 4-20mA output (pulse is cheaper) and then look at Ebay for a totalizer meter to hook it up to. Voila! a fully functional flowmeter and totalizer for around $200 or less that can easily be calibrated very closely.

Rick,

I thought that as well, but they don't a more expensive fuel flow sensor system. When I asked why I was told that they don't know why or when they'll put one on the market. I wonder if there is an intermediate communication device need for diesels due to the return flow sensor requirement that they feel would price them out of competition. Anyway, FL is a fuel miser engine and my reminded me that with some short runs and refills of fuel I can easily determine fuel flow at different rpms. It would be nice to have the rate displayed on my chartplotter was the only real modivation.

Usually once you get an accurate fuel usage on a small diesel...however you choose to do it...guestimations from there on are pretty accurate.

For most cruisers the engine hour meter will serve to know the tank fill state.

patzfan4eva said:

I wonder if there is an intermediate communication device need for diesels due to the return flow sensor requirement that they feel would price them out of competition.

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A truly accurate diesel system does require measuring both streams in order to calculate the difference and display that as the burn rate. That doubles the number of flow meters and increases the computing requirement so it naturally costs more.

It would be nice to have the rate displayed on my chartplotter was the only real modivation.

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For our purposes, a flowmeter attached to an engine that returns very little fuel will be reasonably accurate as long as the return flow is very low and/or constant across the load range. The return fuel can measured the old fashioned way by flowing it into a container and then be be calibrated "out" of the calculation as an "offset."

This type of system won't work on engines with large return flows without two flowmeters.

There are plenty of cheap, plastic or nylon housing automotive fuel flow meters available and their output can go to a cheap flow
totalizer that provides an output readable by your nav system. It might be a fun project if you are into that sort of thing.