Fuel sender wiring Garmin to Suzuki

[localboy]

Looking for some expertise. I have installed a Garmin fuel sensor (GFS 10) to my Garmin 740S. In order to run off the fuel tank sender I need to wire it into the fuel tank level sensor, per Garmin's instructions.

Instructions on the Garmin unit say the level-sensor connector should be labeled with an "S" on the back of the gauge. It isn't.

I have the following on my gauge and cannot find any data on the web:
"+" with "2" gray wire
"-" black wire
"U" white wire

The gray wire also has a resister (I think that's what it is) wired into it. See them here:
http://www.c-brats.com/modules.php?set_albumName=album2522&op=modload&name=gallery&file=index&include=view_album.php

Is the gray wire the sender?

[gulfcoast john]

Not much expertise, but I did intall 2 GFS-10'S on my Garmin N2K network including a 740s and I did muck it up bigtime, and without exploding the boat, but now it all works great.
If the 740s shows the GFS10 and some fuel use (even if 0), at idle on muff on the trailer, I'd say STOP.
My advice is forget connecting the old analog floating-arm primitive rheostat tank sensor...it's still just a primitive float rheostat and converting that to a wildly fluctuating DIGITAL number is not an improvement. The improvement is in the GFS-10 micro paddlewheels dutifully measuring every ounce of fuel passing by, regardless of wave action, rolling, pitching, etc that makes your old analog gauges bounce all over the gauge. WITHOUT the analog level sensor (which is likely a pink wire at the top of your gas tank and likely connected to the white gas gauge "u" wire later) you'll STILL get the EXACT fuel used and, with GPS speed input, the exact GPH. GPH won't be accurate at idle speeds since most modern outboards at idle pull fuel into a VST tank then run off that for a while, and the Garmin paddlewheel is in a position before the engine fuel pump so it can't know that. But idle fuel consumption is nothing compared to cruise so who cares.
Converting a primitive analog inaccurate input into a precise digital number on a digital gauge just doesn't make sense to me, whether in avionics or boating or computing. I like my analog gas gauges, and I won't get rid of them, but I see NO use in converting them to faux-digital 2-quart faux accuracy on a digital monitor. The paddlewheel-measured GPH and MPG is REAL digital accuracy and I love it. It won't know when you add gas or how much (even if you connect it to your fuel gauge) so you input that. No big deal.
I admit again that in doing this project I blew some really buried fuses because I assumed that Yellow wires were 12V neg IAW ABYC standards, but in YamaWorld Yellow is 12v IGN-ON POS. Your gauge Grey wires are likely Ign-On + (you don't want the gas gauges consuming power when the ignition is OFF). My WAG is that the gray wire 'packet' is a fuse rather than a resistor...it has to have a fuse somewhere. Mine were in godawful harness behind the water heater, and to access it I had to remove the water heater, so you're golden.
Per Garmin instructions, if you do not connect the GFS10 to a fuel gauge, connect the brown wire to ground and leave the grey wire unconnected and also the orange wire if you didn't build a N2K network. Good Luck!
John

[localboy]

Thanks, John. I'll look at all this after the weekend. I was not too sure about the analog sensor but figured it was there for a reason. Based on your input, I'll probably forgo that connection.

[jkidd]

Get this cable interface.


It will connect to the computer on the motor and will give you the most accurate reading.

You will need to cut the end off of it and solder on a Garmin end as it has a Lowrance end on it.

You can get it from Browns Point Marina and it will display all of your motor data as well on the Garmin MFP.

On mine I spiced together a Garmin and Lowrance cable so I have a Garmin terminator at one end of the network and a Lowrance at the other end then I didn't have to cut end off of the sensor avoiding the warranty problem.

[gulfcoast john]

The downside of Jody's or any engine networking interface is
1. not compatible with older engines, 2006 or so depending on maker
2. if not already rigged, you have to fish the sensor cable from the engine plug under the cowling through the crowded rigging tube, which in my case was much more trouble and expense than it was worth (required removing shift and throttle cables and re rigging them, which is beyond my comfort level). It may be easier in smaller simpler engines.

Upside is additional engine info besides fuel mgt (temp, water press etc depending on engine make). Upside of a simple fuel line paddlewheel is more compatibility and simpler installation.
Happy boating!
John

[localboy]

I appreciate Jody's input. But it appears way too advanced for my skill set. Electrical is my Achilles heel. I didn't even wire my VW when I rebuilt it. A buddy came over and helped me and he did a professional job.

[jkidd]

I put a paddle wheel type on my boat first and I found that if you spend a lot of time at idle they are inaccurate. As long as you stay above 1000 rpms they work pretty good. My motor is a 2007 DF115 not on the list off motors that will work with the interface but it does. The only part that I have never been able to get to work is the motor trim. I didn't have take apart anything major to install it. I does read correct at idle. If your game I think we can talk you through the install or you could have your friend over again. They network cable has 4 wires a plus and negative and 2 data wires. The plus connects to the plus and neg to the neg. They data wires just don't work till you get them right, hook them up and reverse them if they don't work.

[localboy]

Looking for yet more input on this. So here is where I stand with this.

-I wired the GFS10 to the Garmin 740S without the analog fuel gauge connection; brown wire to ground and the gray wire unconnected
-the fuel level (that I entered) shows up in the upper left corner of the fuel gauge screen/window. We used the boat and the numbers lowered a few gallons, so that is working.
-the GFS10 shows up in the system screen/NMEA 2000
-software is up to date; I just up-dated it yesterday

The fuel flow (gph) does not show anything in the engine gauge screen. Nada. Nothing. Zilch. The little window at the bottom of the "gauge" is blank.

I have checked all the wiring, the NMEA 2000 system backbone etc...nothing obvious.

I have an email in to Garmin support, but thought I'd bounce it off the brain trust too. I must be missing something.

[localboy]

So far Garmin support has been useless. They recommend I update the software. Already done. Waiting for a response. I may just call them tomorrow.

[gulfcoast john]

Not on the boat, but by memory "Engine Gauges' is the wrong screen... that's for info pulled directly from the engine ECM when you've hooked that up with the other DIRECT ENGINE TO NETWORK option discussed above. Of course it's blank, there is no connection there.
Look on the 740 for an option more like 'Info' 'Numbers'...You are there if the GFS10 is showing up on the N2K list and gallons are going down...you're just on the wrong screen.
Cheers!
John

[localboy]

http://www.c-brats.com/modules.php?set_albumName=AU-KAI&id=Capture&op=modload&name=gallery&file=index&include=view_photo.php

So not this screen? Hmmmmm...going outside now to look at this.

UPDATE: You were 100% spot on, John! My mistake.

I went right past the "numbers" screen in the "information" screen because it was not programmed to show fuel flow. Little did I know I could input what I wanted the screen to show, including the amount of screens. I input "total fuel left" and "fuel flow" in two of the six windows. I feel like a dolt. Thanks aka Mahalo!!!

[gulfcoast john]

When we finally tow out there, you owe me a beer.
No reasonable person would say that this situation is 'intuitively obvious', esp when Garmin tech support didn't say so (re a Garmin 740 screen). If Garmin were to ask me (I can assure you that they won't), I'd mark that 'Engine Gauges' screen with a "per Engine Network" emblem or SOMETHING to clue in the end user that a GFS10 or other non-engine sensor input won't show up there.
I get that the N2k or any protocol has to label ENGINE data differently than OTHER SENSOR data, but Garmin's GFS10 install manual doesn't even address COM with a Garmin MFD, and it should.
Cheers! You'll love it!
John

[localboy]

That's a deal, John. We won't be making it down south until I retire.

I looked thru every manual etc from Garmin. I read thru numerous threads on various websites, and could not find an answer. What really confused me was the unit was "seeing" the sensor, so I knew it was "working". I just felt like I was missing something, and probably something obvious. Turns out...I WAS! Thanks again.