Lowrance Fuel Flow sensor

[CDory23]

Hi all,

I"m considering purchasing a Lowrance Fuel flow sensor:

http://northernmarineelectronics.com/lo ... 11517-001/

This would be for my HDS 7 Gen 2 touch. This isn't a necessary addition but I'm curious as to my fuel flow at certain RPM's and I think it would help me optimize my fuel usage and be handy on longer trips such as Catalina island. I also just think its a cool gadget in general. I have twin outboards and I was considering just buying one and putting it in line between my fuel selector switch and fuel filter/water seperator. This obviously will only give me total fuel usage and not separate engine data. Does anybody have any experience with these and/or any reasons why I should consider purchasing one for each engine?

Thanks

 

[ssobol]

Hi all,

I"m considering purchasing a Lowrance Fuel flow sensor:

http://northernmarineelectronics.com/lo ... 11517-001/

This would be for my HDS 7 Gen 2 touch. This isn't a necessary addition but I'm curious as to my fuel flow at certain RPM's and I think it would help me optimize my fuel usage and be handy on longer trips such as Catalina island. I also just think its a cool gadget in general. I have twin outboards and I was considering just buying one and putting it in line between my fuel selector switch and fuel filter/water seperator. This obviously will only give me total fuel usage and not separate engine data. Does anybody have any experience with these and/or any reasons why I should consider purchasing one for each engine?

Thanks

I have one on my dual tank single engine installation. The manual says the sensor should be after the Racor filter. The sensor needs to be installed in a certain orientation.

Out of the box it is calibrated pretty close. You can refine it if you want. At low engine speeds there may not be enough flow for the detector to sense. If you spend a lot of time there your readings might be off. At low engine speeds on FI engines you might see the FF go from zero to some value and then zero again as the low pressure pump on the engine cycles.

I use the LMF-200 display. With a GPS input you can get remaining range in addition to FF, MPG, Fuel Used.

If the unit is on and you get a low bus voltage (e.g. during engine start) you can screw up the saved info and the values reset. I found it is better to have the unit off during starts to prevent this from happening. Same thing happens to the battery monitor.

Since the sender is a bus device and "smart", sometimes it does not initialize correctly. You have to reboot it by cycling power or rescanning the NMEA network although this may be an issue with the display unit and not the sensor). While you can hook the network up to the ignition switch, it is handy to have a power switch for the sender or the network for this purpose and the low voltage issue mentioned above.

I was most interested in the remaining range function. I found that after using the FF indicator for a while that the numbers are pretty consistent (at least on my boat). So the indicator is a bit redundant now. I know the FF at various RPMs and can do the math in my head. We have a comfortable cruising speed for our boat that we travel at a majority of the time (~18 mph) if conditions allow.

The remaining range is calculated dynamically. In rougher water the value will change as the boat speeds up and slows down in the waves and the engine revs change. So you may have to filter the numbers in your head to get an idea of the actual remaining range.

The sensor is mechanical (an impeller in a tube). It can fail or get jammed up. I've had one sensor fail pretty early on (second day I used it).

It would be nice if there was a portable system you could rent or borrow that was self contained and easy to hook up. One could use it for a couple of days to get the numbers and then return it/send it to the next guy. You could reuse it every couple of years to revalidate your cruising numbers or after an engine refit.

All in all it is interesting information. However, I still look at the sight gauges for the tanks regularly to check the remaining fuel quantity.

 

[journey on]

Journey On has a fuel flow meter. The fuel flow is interesting but you get what you get. On a 25, that's 4 g/nm at hull speed and 2 g/nm at cruise. A flow meter doesn't allow me to "optimize" the flow because I want to travel at a given speed in a certain condition. So fuel flow by itself isn't too useful.

What is useful it total flow. It'll tell the gas you've used and that's important when you've been out a week or so. Fill the tank when you start (or some other baseline), do a little subtraction and you have what's left.

If you have 2 engines and you want the flow to each engine, you need 2. If you only want the total flow, obviously you can get by with one. I only have 1 engine on Journey On.

Google the flow meter on the internet. It's a little cheaper elsewhere. And since it's NMEA 2000 it can run with your display or any other NMEA 2000 display. You have to buy the starter kit.

Boris

 

[thataway]

I have had several of these. You can put a fine mesh filter (does not have to be the Racor) before the sensor. You must have a filter however. They sensors must be installed as specifically oriented. I had several fail. Just buy another! They are simple turbine devices. Reasonably accurate, except as noted at low speeds.

To avoid the problems at "startup" have the electronics on a separate battery from the engine start battery. Use a voltage sensitive relay, and the electronics or house battery will start charging when the start battery reaches about 13.7 volts.

I learned the hard way, over 45 years ago the hard way, that you don't want expensive electronics on the start battery because of low voltage and voltage spikes. Today's electronics are far less sensitive than they were in the early 70's.

Often twins will burn different amounts. Most like to have two sensors for twins. Agree with what ssobol stated. They are especially useful when you have a long trip and need to manage your fuel.

 

[hardee]

That one will measure down to 0.6 gal/hr. Might be low enough to keep tabs even at idle. I had looked at fuel flow sensors a long time ago, but they would not read low enough for a 40 HP, and as mentioned, I thought there should be one on each engine. (Mine are 40 Yamis, and each engine runs of the tank on that side --> Port tank feeds port engine, starboard feed starboard engine.)

Having the fuel flow info would be great, but I can see my tanks, and can see the fuel level in them, so it's easy to watch the thirds.

Let me know how these work for you. If I remember right you have twin Yamis also. Hope it works well.

Harvey
SleepyC :moon

 

[ssobol]

That one will measure down to 0.6 gal/hr. Might be low enough to keep tabs even at idle.

My BF90D only shows intermittent fuel flow at idle when the low pressure pump picks up fuel to feed the high pressure pump. There must be a reservoir of some sort in the power head that only needs to be replenished from time to time when the engine is idling.

 

[thataway]

That one will measure down to 0.6 gal/hr. Might be low enough to keep tabs even at idle.
Harvey
SleepyC :moon

The installation instructions say

This sensor has been optimized to measure flow rates between 0.6 to 45 gallons

My experience (3 engines) is that it is not accurate at less than 1 gallon per hour for current consumption. It seemed to be fairly accurate for total fuel used...but I spend very little time at idle.

Boat Test.com C Dory 22, with 90 Honda, shows 0.5 g/h at 670 RPM. the same at 1000 RPM and then 0.8 g/h at 1500 RPM. (Flow scan digital or factory on board diagnostics. For the 25: They show 0.6 g/h at 1000, and 0.9 at 1500. In both cases the lowest RPM has a lower "range" than at the next higher RPM...That defines logic--and points to the fact that all of these type of fuel flow meters are not accurate at lower flows. There are some flow transducers which are more accurate at low flows, but Lowrance is not one of them.

 

[hardee]

Bob, Thanks. Flow Scan was the brand I looked at originally. And the Boat Test. com numbers shown are for a single 90. My 40's would be less than half, probably. Having the total flow I could divide by the hours used, and get usable numbers, but for my use, just looking at the tanks has been pretty successful.

Harvey
SleepyC :moon

 

[ssobol]

That one will measure down to 0.6 gal/hr. Might be low enough to keep tabs even at idle.
Harvey
SleepyC :moon

The installation instructions say

This sensor has been optimized to measure flow rates between 0.6 to 45 gallons

My experience (3 engines) is that it is not accurate at less than 1 gallon per hour for current consumption. It seemed to be fairly accurate for total fuel used...but I spend very little time at idle.

Boat Test.com C Dory 22, with 90 Honda, shows 0.5 g/h at 670 RPM. the same at 1000 RPM and then 0.8 g/h at 1500 RPM. (Flow scan digital or factory on board diagnostics. For the 25: They show 0.6 g/h at 1000, and 0.9 at 1500. In both cases the lowest RPM has a lower "range" than at the next higher RPM...That defines logic--and points to the fact that all of these type of fuel flow meters are not accurate at lower flows. There are some flow transducers which are more accurate at low flows, but Lowrance is not one of them.

I wonder how they determined the low speed fuel flow. In the engine or at the input fuel line with some sort of meter. Perhaps they have a precision flow meter, rather than a consumer unit. My boat shows intermittent fuel flow at low speeds. My reading about FI engines says this is typical as the low pressure pump cycles. Maybe they average the pulses out to get the fuel flow or measure total fuel used for awhile and do math.

 

[thataway]

I chose that example, because the flow meters do not show accurate flow at low idle speeds. The most accurate way, is with measured fuel container, and amount of fuel used vs time. This is the way it is often measured for long distance cruising boats, where accurate consumption is essential for the range to cross oceans. Boat Test, uses Flow Scan--which suffer from the same issues as other meters. From the engine, is usually from the computer which most injected engines have.

 

[gulfcoast john]

C-Dory 23,
Most outboards after 2006 vintage have a plug from the ECM that can be plugged into your existing N2K network or MFD and get fuel info plus lots more engine info 'for free'. Suzuki plays well with Lowrance.
I didn't do that because Yamaha insists on an isolating hub, and the rigging tubes are too full to snake through. 2 Garmin GFS 10's are cheaper and I could rig them myself. The scariest part is cutting the fuel lines, usual precautions. No reliable idle readings, but fuel flow is tiny there and can be computed separately if needed.
Just something to be aware of and do your own cost/benefit check.
Happy Rigging!
John

 

[ssobol]

The commonly used Honda BF75D/90D does not do NMEA. Don't know about the 115. The 90 was one of the few Hondas that don't have it.

Hondas in ~90HP class did not get NMEA until the BF100 came out.

 

[starcrafttom]

[url=http://www.interactio.co/optio-fuel]http://www.interactio.co/optio-fuel [/url]