How To Plug An Old Engine Into NMEA 2K

[San_Diego_SeaRay]

Hello All -

I have a carbureted '93 Mercruiser 7.4 engine and I'd like to use the NMEA 2k network to monitor things like RPM, oil pressure, voltage, and water temp. Basically make my analog gauges obsolete.

Apparently there are some devices out there that allow you to plug analog signals into them and they will convert it to a digital signal that is compatible w. the NMEA 2k protocol. The most promising one to me looks like the Actisense EMU-1.

Does anyone have any experience w. this Actisense? Or any other of these types of devices? I was wondering how reliable and simple they are. I've heard that some devices don't play nice on the NMEA 2000 networks.

The NMEA network would be plugged into my Garmin GPSMAP and that's how I'd be doing the engine monitoring.

Thanks in advance!

 

[sam am I]

Or any other of these types of devices?

yes............

I was wondering how reliable and simple they are. I've heard that some devices don't play nice on the NMEA 2000 networks.

Seems solid enough and true, the particular analog sensor/s have to scale properly for the what is expected at the particular input/s.

 

[QBhoy]

I know a guy that did it himself…and literally for some ridiculous pennies worth of a sum of money. On the other end of it..I know a guy who bought a kit to do the same for his Volvo Penta too.
Maybe wise to be aware that some (not all) may need additional gateway to work with the plotter. Some don’t though (wiry regards to simply going from analogue like yours to nmea..and with compatible mating.
Nice modern update perhaps, but obviously the data will only be as accurate as the sender’s ability to send accurate parameter variance (just like they do with gauges previously…as in, not terribly accurate on some occasions).
Having ecu fed data on two of my own boats…I was really surprised at how far out some of the dash analogue gauges read, in comparison. In particular the tachometer at higher rpms and the temperature gauge too.

 

[dingbat]

Having ecu fed data on two of my own boats…I was really surprised at how far out some of the dash analogue gauges read, in comparison. In particular the tachometer at higher rpms and the temperature gauge too.

In reality, I think your going to find the digital data is not as accurate nor up to date, as the "instantaneous" analog signal

The resolution and averaging times of A/D converters is no where near that of analog.

To this, you have to include the update rate of the NMEA link and the update rate of the display itself.

 

[San_Diego_SeaRay]

In reality, I think your going to find the digital data is not as accurate nor up to date, as the "instantaneous" analog signal

The resolution and averaging times of A/D converters is no where near that of analog.

To this, you have to include the update rate of the NMEA link and the update rate of the display itself.

Thanks and good point. I actually don't mind a lower refresh rate w. digital. Accuracy, yes. That would be more of a problem.

But really I like the thought of being able to manage everything through one multi-function display. Not only does it save on real estate, but then you also have the possibility of plug and play expandability. Here are some cool things that I would be able to monitor from the MFD using NMEA:

Fuel flow rate
Fuel Tank Level
Miles Per Gallon (or Gallons Per Mile )
GPS Speed
Paddlewheel Speed
Gallons Per Hour
Trip Avg Miles per Gallon
Trip Fuel Used
Water Temperature
Depth
Alternator Voltage (and starting battery voltage when engine is turned off)
House Battery Voltage
Oil Pressure
RPM
Trim Position

My boat is from 1993 and the gauges are getting old. The Tach already doesn't work. If I get new gauges I'm already 50% into the cost of getting one of these engine monitoring thingies. And then and going forward I'll have a NMEA network to build off of. I can always keep the gauges (and probably will) as a 2nd reference.

The "monitoring gas useage" is actually the main reason why I'd like to get into the NMEA technology. I bought an LMF-400 digital gauge w. a fuel flow sensor. Later found out that my Garmin GPSMAP could do the same things as the LMF-400 . And the ability to monitor the engine will just be a bonus to my fuel monitoring priority.

 

[flashback]

Can't help you but I think your headed for endless problems.. that said, good luck!

 

[QBhoy]

In reality, I think your going to find the digital data is not as accurate nor up to date, as the "instantaneous" analog signal

The resolution and averaging times of A/D converters is no where near that of analog.

To this, you have to include the update rate of the NMEA link and the update rate of the display itself.

Can’t beat ecu provided data on injector pulses and rpms to be honest.

 

[dingbat]

Thanks and good point. I actually don't mind a lower refresh rate w. digital. Accuracy, yes. That would be more of a problem.

But really I like the thought of being able to manage everything through one multi-function display. Not only does it save on real estate, but then you also have the possibility of plug and play expandability. Here are some cool things that I would be able to monitor from the MFD using NMEA:

Fuel flow rate
Fuel Tank Level
Miles Per Gallon (or Gallons Per Mile )
GPS Speed
Paddlewheel Speed
Gallons Per Hour
Trip Avg Miles per Gallon
Trip Fuel Used
Water Temperature
Depth
Alternator Voltage (and starting battery voltage when engine is turned off)
House Battery Voltage
Oil Pressure
RPM
Trim Position

My boat is from 1993 and the gauges are getting old. The Tach already doesn't work. If I get new gauges I'm already 50% into the cost of getting one of these engine monitoring thingies. And then and going forward I'll have a NMEA network to build off of. I can always keep the gauges (and probably will) as a 2nd reference.

The "monitoring gas useage" is actually the main reason why I'd like to get into the NMEA technology. I bought an LMF-400 digital gauge w. a fuel flow sensor. Later found out that my Garmin GPSMAP could do the same things as the LMF-400 . And the ability to monitor the engine will just be a bonus to my fuel monitoring priority.

The problem you run into is that none of this data is available from a motor in 1993. You will need to buy and install individual sensors for each function.

Things like paddle wheel speed you can buy Plug and play NMEA sensors but most will require a break out box like the NMEA convertor above.

The Garmin GFS-10 works well. Been running it for almost 10 years now.

 

[QBhoy]

The problem you run into is that none of this data is available from a motor in 1993. You will need to buy and install individual sensors for each function.

Things like paddle wheel speed you can buy Plug and play NMEA sensors but most will require a break out box like the NMEA convertor above.

The Garmin GFS-10 works well. Been running it for almost 10 years now.

You can use the original sender units on the engine. Just need to convert and calibrate the signal from them to suit. Thought I’d mention, if it’s helps.

 

[San_Diego_SeaRay]

The Garmin GFS-10 works well. Been running it for almost 10 years now.

Yep. And a huge advantage that the GFS-10 has over my Lowrance sensor is that it not only measures fuel flow but it ALSO monitors fuel tank levels and dumps that info into NMEA 2k. Two birds. One stone.

 

[Jllindy]

Hello All -

I have a carbureted '93 Mercruiser 7.4 engine and I'd like to use the NMEA 2k network to monitor things like RPM, oil pressure, voltage, and water temp. Basically make my analog gauges obsolete.

Apparently there are some devices out there that allow you to plug analog signals into them and they will convert it to a digital signal that is compatible w. the NMEA 2k protocol. The most promising one to me looks like the Actisense EMU-1.

Does anyone have any experience w. this Actisense? Or any other of these types of devices? I was wondering how reliable and simple they are. I've heard that some devices don't play nice on the NMEA 2000 networks.

The NMEA network would be plugged into my Garmin GPSMAP and that's how I'd be doing the engine monitoring.

Thanks in advance!

View attachment 388525

Did you ever find a solution, I have looked into the exact same upgrade but the actisense is out of my budget…I did find a cheaper option on eBay…my motivation is the same as I would like to replace my gauges with a Garmin 93SV