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New inexpensive product to display engine data on your NMEA2000 compatible GPS/Multi-Function Display

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I am currently developing a small electronic product that retrieves data from your boat engine's computer (ECM, ECU, etc) and broadcasts it on your NMEA2000 compatible network so that it can be displayed on your GPS/Multi-Function display.

The installation is easy. Simply plug it into the engine's existing diagnostic 10-pin plug and connect the other end into your NMEA2000 compatible network using the supplied T-connector and drop cable. Thats it. Now you'll have engine data on your GPS updating once per second.

What engine data is broadcasted? Fuel Flow Rate, Engine RPM, Engine Coolant Temperature, Engine Run Hours, Battery Voltage, Various Alarms (High Engine Coolant Temp, High Exhaust Manifold Temp, etc).

What engines are compatible with this? Thats a great question and I need your help to find out. I designed my product to be compatible with my 2002 Four Winns 268 Vista which is powered by a single Volvopenta 5.7gxi-b using a MEFI-3 ECM model #16237009. The MEFI-3 ECM is made by Delphi and is used with many other engines including Mercruiser as well.

There are several different model numbers associated with the MEFI-3 ECM and I want to make sure my product is compatible with all of them. Additionally, the MEFI-4 shares many similar characteristics to the MEFI-3 and would likely be a good candidate for a future version of my product.

Who am I? My name is Allen Murrow and I'm a Nuclear Reactor Operator for a local power company. I happen to have a broad range of interests and hobbies that made developing this product challenging and fun, but most importantly, achievable. I dabble with computer programming, websites, microcontrollers and electronics, machining (lathe and mill operations), welding (MIG, TIG, and Stick), hydraulic equipment repair, and boating.

I expect to sell my product for about $210 each. This price will depend on the demand though. If there is a high enough demand, I may be able to get a much better deal on the individual components and circuit board printing.

The purpose for this post is to gather data on the number of people interested in purchasing this product. I would also like to hear from those who would want to help test this on their MEFI-3 ECM and I would like to hear from those who would be interested in a MEFI-4 version.

Please understand that I do not run a business. I have a personal life with my beautiful wife and an adorable 1 yr old daughter (and a Rottweiler, a Pit bull, and a Great Dane). This product does not yet come with any warranty nor do I assume any responsibility for any potential damage occurring during its use. This product only suggests that it is "compatible" with your NMEA2000 network and devices. It is not NMEA2000 "certified", "approved", nor any other word that would lead one to think that I would be required to pay a license fee for its use. All of the technology used to create my product was publicly and freely available on the internet. The goal for this project was to produce an affordable product in our overpriced marine electronics industry while attempting to earn some startup capital to create a small Research and Development business to pursue additional marine electronics products and technologies. Eventually, I plan to seek certification from the National Marine Electronics Association.

Thank you for your support.


60 Replies

  • I think you might find more testers if you can specify other engines that come with similar MEFI-3 ECM's.

    Also, I'm curious if the MEFI-3 uses J1939 as its native data protocol. In that case, Maretron already makes a gateway:

  • Thanks for the reply. The MEFI-3 does not use J1939. If it did, I would not have created my electronic device, I simply would have just purchased one. I know there are analog based units that connect to individual sensors, but they are expensive, complicated to setup/calibrate, and they would not offer fuel flow (unless you already had a fuel flow sensor). My device receives the fuel flow rate from the ECM.

    As for the suggestion about listing other engines that use the MEFI-3, I do plan on compiling a list. But for now, I wanted to let the boating community know that the product exists (in a development stage). I have already devoted several months to this project and am seeking assistance on identifying the other compatible engines. My wife and child appreciate this decision.

  • I have 2005 Crusader 6.0's with MEFI4, they don't support J1939. I have expolored the Maretron solution and they can be added if you change out the ECM, an expensive proposition. Livorsi currently has a device selling for $500 per engine that will support MEFI 4B, and connect to the NEMA2000 back bone with a cabling kit +/- $125, so all in cost for that for twin engine is $1200. I would be interested in your solution because of cost, but some assurance it won't grenade an 1800 ECM would be comforting.

  • Hi Allen -

    Sounds like a great idea...I have a 1998 Suzuki DF70 which has the MEFI-4, I believe. I would be interested in your product for testing when it becomes avaialble.


  • I think this is a great idea. I Was researching the possibility of doing this myself when I came across your post. Glad to see someone else taking this on. I have a 1999 380 Sundancer with Mecruiser 7.4 Horizon which are mefi 3. I have just purchased a mefi scan to start the research. I would be interested in purchasing/testing/assisting with your unit. I am an electronic technition and have some experience with interfaces,protocols, and marine electronics.

  • Great idea, I came across your thread as I was researching a way to do exactly what you are talking about. Glad to see someone taking this on. I currently have a 1999 380 sundancer with Mercruiser 7.4 Horizon engines which are mefi 3. I have just purchased mefi scan to experiment with talking to the mefi controller. I would be interested in purchasing/testing/helping with your unit. I am an electronics technician and have some experience similar technology.

  • Thanks for the replies. Please contact me at allen.murrow at so we can discuss some specifics related to testing. The MEFI-3 version is fully functional and has been used on my boat for several boating trips from the North East River to the Bay Bridge, Middle River, Chesapeake City, the Susquehanna River, and everywhere in between. I will build a few more hand soldered development version boards and will start fine tuning the circuits for a production run on a printed circuit board in a month or two. I'd like to finish this MEFI-3 version first so the MEFI-4 version will not likely be available until next year.

    On a related note, part of my engine gateway obviously needs to interact with the NMEA2000 network on my boat in order for the GPS Multi-Function Display to receive the engine data. To make this connection easy, I purchased a certified NMEA2000 panel mount connector from Actisense and an additional T connector and drop cable from Garmin. In my opinion, those cabling products are very expensive so I decided to pursue and affordable alternative which is not currently NMEA2000 certified. My non-certified cabling products will be included in both the test versions and production versions of my MEFI-3 engine gateway and will also be available separately for those who just wish to save money on NMEA2000 compatible cabling products. I plan on creating a website with videos, pictures, and detailed descriptions of my cabling products as related to wire size, shielding, resistance, costs, and more details on the engine gateway. As I stated in my original post, I do plan on eventually obtaining certification from NMEA2000 but before I spend time and money on that, I'd rather focus on making the best affordable product available. The cabling certification is separate from the engine gateway certification but is definitely something I will pursue. There is no reason why fully certified NMEA2000 cables can't be sold for a realistic price. Those 5 pin waterproof connectors have been in use for a long time and in many other industries. For those who wish to test my MEFI-3 engine gateway, I would also appreciate your feedback on the cabling products I had manufactured.

  • Will this interface with 2005 Volvo 675hp diesels- if so - can you please send me details of your product and please elaborate on installation procedure or issues.
    thank you ,

  • Allen, I have been pursuing a solution for MEFI display for years. The 2 commercial ventures that exist(ed) are B&G Instruments Network Engine, and the still available MEFI Scan. You probably know this already.
    I have a number of vessels that have MEFI-1 and MEFI-3 computers. I am also a Systems Engineer, and Electronics Engineer. Just never had the time to sit down and do this myself.
    I am located in Florida and Alabama.
    If you would like to pursue testing with MEFI-1 and 3, send me an email to an intermediate account I use, and then I'll get back to you with my daily email. use dadsgearcloset at yahoo. Looking forward to finally getting some traction on this.

  • Wouldn't it be nice to get the Pre-2008 Honda Outboards on your list! A ton of their proprietary "digital" OB's (now without a Digital Honda gauge option - since they discontinued them in 2012) exist. I admit I have no idea what protocol they use, but Id be in for two of your gauges if they were.

  • The inboard engine population is sizeable but the outboard number is vast. If your skills and interests include outboard engines the potential may be worth exploration.

  • Another thought is to explore converting from MEFI to ODBII. Then, you would have hundreds of apps, tons of display possibilities, and connectivity options.

  • I would definitely be interested in seeing this materialize. I have a '99 Horizon 240 with the 7.4Gi engine (L29 454 utilizing MEFI3). I've had a couple of ECM/fuel injection related issues since I acquired the boat. I have done quite a bit of testing with a DMM among other things, and have repaired the issues found with no change in performance. The only available tools that can read these MEFI ECM's are pricey, albeit worth it I'm sure. (Techmate, Merc. Scan Tool, Diacom, etc.) Let me know if you need any help whether it be testing, electrical/electronic assistance, whatever. Count me in!

  • I have twin 2004 Crusader 8.1's with MEFI-4b ECM and would be interested in seeing what your product would do for monitoring on my Raymarine E120 Classic MFD.

  • I would be interested in testing as well. I have a 2001 Volvo 5.7 GSIPEFS with a MEFI 3 (#385888). Would love to have a MEFI3 to NMEA converter to connect my display to the engine.

  • I have 2 Horizon 385hp in my 1990 350 and there is no good interface for the alarm system. I would be very interested in one and if possible a Y connector and ability to switch between motors.


  • So did this project get off the ground? I have a Mercruiser 350 MAG MPI that uses a MEFI 2 or 3 and I would absolutely love to tie in sensor values into my electronic system. Is the device available?


  • I have a 1997 Sea Ray Express Cruiser with twin 7.4 EFI Throttle Body engine that I would like to monitor. Would your product work for these ?

  • I have 1 1999 SeaRay 340 Sundancer. 7.4 MPI engines (inboard). Would like to setup a laptop or iPad to monitor MEFI info from ECM.

  • Taking a 5.7 gsi pefs off one engine and putting it on mine. I have a flow meter, but am baffled what if my engine quits so am trying to learn. any input would be nice. was a techie in my other life (vacuum tubes) but this stuff hangs me out to dry

  • I have a 2016 4.3 efi mercruiser with a hummingbird Helix 9. I have interest in your product.

  • I have been using 2 of these units for 6 months on my 1998 370 Sundancer communicating over bluetooth to 2 iphone 6S for dual display, or 1 phone and the ability to select which engine I wish to monitor.

    The units are mounted on the forward engine room bulkhead and I have reception at the helm and in the cabin with no issues.

    The next things I would like to see from Fox Marine is a monitoring app on Android, and a simple display app on either that lets you pick the PGNs you wish to monitor, and display them as virtual gauges or readouts on my phone/tablet.

  • I have 2002 crusaders, 350s I am interested in your product. Can you send me some information about the product and the cost.
    thank you

  • Older marine diesels lack electronic monitoring systems. My 1977 Perkins has only oil pressure, engine temp and a very inaccurate RPM gauge.

    I built an Arduino-based monitoring system that costs about $125 to build. Everything is open source and the code and schematics are published to

    The system currently displays basic engine data to a 16 X 2 LCD mounted on the dashboard and connected to the main Arduino enclosure using CAT6a. The "next" button pages through the sensor output:
    - Raw water in temp
    - Raw water out temp
    - Coolant entering HX temp
    - Coolant exiting HX temp
    - Cyl head temp
    - Engine room temp
    - Oil temp
    - Exhaust gas temp
    - RPM using a hall sensor, very accurate

    Now that the first phase is complete there is demand for the device to publish the engine data to NMEA devices such as chart plotters.

    Your system seems like a perfect marriage, to bridge this data from older engines to more modern NMEA chartplotters.

    I was thinking about doing the NMEA integration myself, however if I could provide an output plug and the correct protocol to your device it would greatly simplify everything.

  • Have we heard back from the OP since 2014? Is the OP reading this forum?

  • Hello Rob, will your system work with gas engine? I will check out the site you address.
    Maybe we can talk further.
    Thanks Allen shelton

  • Short answer: yes, I'm here and reading all replies. Long answer: wait for detailed reply this weekend.

    Someone recently mentioned the business name I had formed to pursue this project further but I'll be posting a link and a bunch more info after I finalize some more details on my website this weekend.

    Thanks again for everyone's support.

  • The MEFI-3 engine gateway that started all of this has progressed into four separate engine gateways: MEFI-1, MEFI-2, MEFI-3, and MEFI-4. All four models are currently available on my website Please review the FAQ page for more details. I plan on starting an advertising campaign after the details are finalized with another local business which will be supplying my fully assembled/soldered circuit boards with surface mount components within the next few months. For now, the printed circuit boards are either sourced out for hand assembly/soldering or I personally take on that task when time permits.

    I expect to receive my next batch of cabling products soon and will post those details when they become available.

    Thanks again for supporting and following this idea from a project to a small business.

    Fox Marine, LLC

  • Hi
    I currently run a 2007 fourwinns with a pair of volvo penta 8.1's and wondered if i could use your product to display my engine data?

  • Hi allen
    I'm currently run ing twin volvo 8.1's in a 2007 fourwinns 378. Any chance your hardware will permit me to see engine date on my chartplotter? (Raymarine E120)

  • Jeremy, my MEFI-4 engine gateway should work for you. Refer to my FAQ page for details on connecting to your Raymarine E-Series. You should email volvopenta with your engine model number to have them confirm you have a MEFI-4.

  • I hooked up a Raymarine ST70 MFD over the weekend. It appears to be working with a couple of issues. The default engine display was showing fuel economy in gph, and the fox gateway is broadcasting fuel flow in gph. A simple data display reconfigure fixed that. You may find the same issue in the E series plotter.
    The second issue may be setup related, and unique to my motors, not yours. I do not have the master slave wire on my 1998 MAG mpi 454s. I set one gateway to engine 1 and the other to engine 2 using dipswitch 1. The Bluetooth iPhone app sees both and you can select one or the other. The ST70 usually only sees one gateway, and occasionally the other (guessing by diff in rpm and coolant temp switching back and forth), but I can't find a designation or display setting to select which engine each page should read. Still playing with it.

  • Rereading the installation guide for the gateway, it is a bit ambiguous on dip 2, master/slave. Maybe I need one set to slave for the st70 to recognise there are 2 engines. Allen?

  • Cliff please check your email and call my cell so I can help troubleshoot.

  • I wanted to let the viewers of this forum know that the Raymarine ST70 Instrument Display issue described above was the result of both engine gateways configured with dip switch #1 in the down (off) position. Essentially, both gateways were trying to broadcast data as if they were the port engine.

    The ST70 Instrument Display is fully compatible with Fox Marine Engine Gateways. I validated this by working with the customer, purchasing my own ST70 Instrument Display, and borrowing one from a friend.

    As a result, I will be updating the Installation and Operating Instructions to not only clarify the various uses for the dip switches but to also include a Troubleshooting section.

  • Hi Allen,

    I have 02 fountain with twin 377 scorpion motors with the mefi-3. I would like to connect them to my simrad go7 using the nema2000 connection. Is it possible with your setup?

  • Yes Rick, your ECMs (MEFI-3) and GPS (Simrad GO7) are compatible with Fox Marine products.

    Assuming you don't have a NMEA 2000 (N2k) network setup yet, here’s your material list:
    2 qty Fox Marine MEFI-3 Engine Gateways
    2 qty Fox Marine (or equivalent) N2k T-connectors
    2 qty Fox Marine (or equivalent) N2k 2m Drop Cables
    1 qty N2k Starter Kit (Lowrance 124-69 or Garmin 010-11442-00)(with 15ft backbone or 32.8ft backbone respectively)
    1 qty Aux Switch at your helm to power the N2k network

    Take a look at the FAQ page, Photo Gallery, and instructions on my website ( for more details.


  • So i have a 2000 johnson 200 ocean pro, i love my motor, but id love to get rid of all my gauges and have it go through my gps, is this possible yet? 813 394 0333. Thanks, Randy

  • Randy,

    Unfortunately, the Fox Marine Engine Gateway models currently available are only for MEFI-1/2/3/4 ECMs and would not be compatible with your outboard. As Fox Marine expands, I’ll keep your engine in mind for a future compatible product.



  • Allen,
    Does your device work with Pre-NMEA2000 HONDA outboards? I'm after fuel burn information etc to interface with my Garmin unit.


  • I have this installed on 2000 Mercruiser 7.4 MPI. Easy install and works great. I removed my tack and speed gauges and replaced them with Lowrance NEMA gauges.

    One question. The total engine hours on the bluetooth feed seems to change. Was 300 or so, then 1000 or so, and now 500 and change.


  • Thanks for bringing this MEFI-3 engine hours issue to my attention.

    Please check your email so we can begin to troubleshoot and update the iPhone App as necessary.



  • I recently purchased a 2002 Regal 2450 LSC with a 5.0 gxi-b and have a Garmin 527 chartplotter with NMEA2000. I am interested in your product. How do I get started? Thanks, Phillip Neely

  • Phillip, take a look at the FAQ page and instructions on my website

    Using the FAQ page as a guide, you can confirm that your ECM is a MEFI-3.

    Assuming you don't have a NMEA 2000 (N2k) network setup yet, here’s your material list for a single engine setup:
    1 qty Fox Marine MEFI-3 Engine Gateway (confirm MEFI version)
    1 qty Fox Marine (or equivalent) N2k T-connector
    1 qty Fox Marine (or equivalent) N2k 2m Drop Cable
    1 qty N2k Starter Kit (Lowrance 124-69 or Garmin 010-11442-00)(with 15ft backbone or 32.8ft backbone respectively)
    1 qty Aux Switch at your helm to power the N2k network (or power it from the ignition circuit)



  • Seems to be a lot of knowledgeable and helpful people here..
    Maybe this should be in another thread or new one - not sure. Please bare with me if this wrong and help ask in the right way.
    I'm also interested in reading some basic data from a Volvo Penta 4.3 Gi, 1996. I think it is MEFI-1.
    Can anyone confirm this please?

    Also - does anybody know how to read the data? I have all hardware needed and it is only one pin with data to read from. I'd like to get this data into the linux-box serial-port, thats the easy part.
    But what is the format of the data?
    Any help most welcome!


  • I have a 350 Horizon Mercruiser. Will you system work with this motor please.

  • Dear NMEA2000 specialists,

    I am the owner of new Catamaran with two Volvo Penta D2-40 engines. I have standard Volvo instrument at Flybridge stearing wheel, but no motor information at inside stearing place!
    France company Poccon was not able to install two Volvo NMEA2000 gateways to show motor information.
    So what I need: I want to buy 2 NMEA2000 adapters for my both Volvo Penta D2-40 and connect them to my FURUNO NMEA2000 bus to show all motor information.
    Can some helb me, by mail or may be by person?
    Hans (from Catamara Nicole)

  • If I purchase a Gateway and use my Iphone do I need to purchase all the wiring please.

    Has anybody tried on a SIMRAD please

  • I am a bit late to this party, but nevertheless am interested. I have a newish Volvo Penta D2-40F engine and an even newer NMEA network based on B&G Zeus2 Chart Plotter. I'd like to get the Volvo's data on the Zeus. Your gizmo seems ideal. Where are you with the development? What do I need to buy/do to install it. Sounds great...

  • I am a bit late to this party, but nevertheless am interested. I have a newish Volvo Penta D2-40F engine and an even newer NMEA network based on B&G Zeus2 Chart Plotter. I'd like to get the Volvo's data on the Zeus. Your gizmo seems ideal. Where are you with the development? What do I need to buy/do to install it. Sounds great...

  • Hi - I have this installed on a Mercruiser 7.4 MPI from 1998 - MEFI2. It Works absolutely great - BUT I am struggeling to find the right fuel flow (correction) factor. In the APP 10 is the center point - the range is from 1 to 255.
    Any number above 10 will increase the reading and any nubber below will decrease the reading - but which number is correct for the MEFI2 7.4 MPI engine?? Would be great to get this correct - any input/comments anyone?

  • Just checking to see if there has been any update on providing a gateway for my 2000 Johnson ocean pro?

  • I was wondering about the future of the android app. This would be awesome except I don't have any apple devices and currently use an android tablet as a chartplotter. I'd love to be able to use your product.

  • Hello,

    I have 1998 Mercruiser 502 MAG MPI and that will be MEFI 1 ( checked your FAQ on the website). I want to buy, but have som questions.

    Will Use with new Garmin 721xs.

    I noticed mogens from denmark had issues with fuel flow.
    Are you suppose to set some kind of correction ourselves? And like Mogens says, how can we get this right and based of what?

    And how is your device different from the existing
    Mercury OEM Engine NMEA 2000 Gateway Module Part # 84-8M0105243 SS 8M0065208 ?

    Or is it the same but just cheaper?

    On Garmins website it says you will need an adapter of some kind if using the on from mercury for talking to Garmins display ... really confused here.

    check the linK

  • Tried to telephone your office but I got a message the number has been disconnected.

    I am ringing from Australia so perhaps there are issues.

  • Hi Nev, the Fox Marine number was answered from here in the States, but it was voice mail. I'm confident that Allen is still in business and suggest you try email or Fox's web contact page:

  • thank you I will try again

  • wwould this work with a Volvo penta gxi-c if so where do I purchase?

  • Allen, are you still pursuing this system ? I have a 2007 Fourwinns vista with a single Volvopenta GXI and am in the process of installing the fuel data system. Please let me know if you are still pursuing your project.

  • Did you ever finish this product to display engine data on NMEA2000 compatible GPS/Multi-Function Display?
    Does it work for twin engines 2005 Mercs mefi4?