Fluctuating fuel consumption on 2014 DF300

[Fishfool]

One last question please............

I purchased a couple of the maintenance kits to go ahead and give the motors a 200hr service. I was told the spark plugs come pre gapped but I want to check them just make sure they are right. What should the gap be?
thanks!

[FishTales]

This seems like a better topic secession for the discussion of current fuel flow indication problem with my 2014 Suzuki DF225 twin outboard installation. I have the SMIS multi-function indicators installed. 1 for the Port Engine and 1 for Starboard Engine, third for the vessel indications. Once again, the problem is that the starboard engine is indicating about twice the fuel flow that it should be at all power settings.
Moonlighter requested additional information for trouble shooting the system.
Here's the details.
Twin DF225's installed and rigged on a 1997 Pursuit 2870 in February 2014. Old 2stroke Yamaha's and rigging removed. Boat was operated several years as rigged by dealer. I then chose to update the electrical system with a house battery and Three battery selector switch and the 3 bank battery charger. Electrical circuitry was maintained for the engine power side as rigged. New switch has a diode system to isolate engines charge systems/ batteries from house battery system. Installed optional house battery charge indication system, if lite is illuminated house battery is being charged.
Next big maintenance event was February thru April 2021, I did another electrical and electronic up grade. I removed a 2010 Garmin 4208 GPS Chart plotter because it was degrading in operation quality. Also it was indicating low system voltage, down to 10.5 as displayed on the plotter. Voltage indicated on the SMIS gauge to be 14.2. So this boat was exposed to a saltwater environment all those years, up to 2010, had an electrical system resistance problem. In the center console All Molex connector wire terminals were removed from their connectors. Wires were trimmed back to expose non corroded ends, polished, and new correct terminal ends installed. Tube type, old buss fuses and holders were removed and new Bluesea fuse/electrical distribution units were installed along with new system switches located in a more convenient and identifiable location for a senior operator.
A new Garmin GPSMAP 1024 XSV was installed at that time. None of the data bus systems are linked together. Raymarine Auto-Pilot has it’s own system. Garmin System and components have their own system. Suzuki is isolated even more in the fact the only connection, is the charge system to the house battery.
So now, May 2021 the boat is in the water, Lake Erie Walleye are calling and were fishing. No problems for several trips. Everything is playing as advertised. My son goes up to use the boat, needs to put on some additional fuel. Goes to the gas dock, shuts down engines, fuels, cranks up and no standard display on the starboard engine. It runs just fine, no longer has our custom display settings. I learned how to program gauges when installing new battery system. I like vaulted memory, think that what it is, once you program the system it’s in. They go out and have a good day. I get back up to the lake, so now I get things reprogramed to our normal displays. When I crank engines up my fuel flow indication are really messed up. We run as it is, last summer and my wife and I get covid in August, so were shut-down until mid-September. I try to get my tech to look at this problem and it takes to October before he can get to the boat to check things out. He sees what my complaint is, swaps EEC’s or is ECU’s, problem remains on the Starboard side. Boat is coming out of the water in less than a week, so he said they would check it out the data systems during winter layup. He accomplished oil changes and normal 100 Hr. Suzuki maintenance. Check ECU’s for faults, with none noted.
Only one other note, with this installation the engines need to be centered in order to be raised, if not, the rig housing contacts structure, so in 2019 I had the composite material rig housing adapter on the Starboard outboard replaced, during lay-up. Everything passing though the adapter had to be disconnected in order to replace it. What occurred was the + and – power cables were not completely secured. When running I would get some alarms intermittently. Finally, the engine shut-down while trolling. Ok got to find out what’s going on. Pulled the cowl and checked connections and found loose nuts. Tightened, put things back together and continued on. I contacted the tech and he came to the boat checked things out, cleared faults and we continued on.
This is my story, I’m a retired aircraft maintenance tech. Need some tech support.

[Moonlighter]

Background of how this system works:

Engine data goes to the Suzuki interface cable, which translates it into NMEA2000 format and sends it to the NMEA2000 network. The cable runs software designed to work with certain model year engines so its important to have the correct version that matches your engines. Each engine has its own interface cable.

The wiring connections go like this:

- at the engine end (on each engine) there are 2 x harness connection plugs to the ecu on mechanical control (not fly by wire) engines. One is for analogue gauges, the other is the SDS plug which is used for digital gauges/engine data to NMEA2000. When SMIS gauges are used, the harness that goes to the dash is swapped from the analogue plug across to the SDS plug. This sends digital data up thru the harness to the gauge harness behind the dash. (The SDS plug is the same one used by the mechanic to connect their laptop to wheh they use the Suzuki diagnostic program to service the engine and check codes etc)

- behind the dash, the engine interface cables are then plugged into the gauge harnesses at one end, and the other end plugs into a network T piece in the backbone.

Then, any displays that are also attached to the same network can show engine information. Multiple displays can show the same information. Gauges have to be told which engine’s data they should display.

The SMIS “gauges” are really just network displays that can be assigned to show information from the engines and/or other sources such as GPS (speed), and they can do other functions such as combine speed and fuel flow to calculate and display fuel economy.

Therefore, when engine info goes missing, the cause is either a physical wiring issue in the network wiring (corrosion, loose or broken wires in plugs or in the engine harness) as described earlier or, its an issue with the interface cable doing its job of transmitting the engine data to the network.

Interface cables can go bad, their software can get corrupted, or their connections to the network T or to the gauge harness can be damaged. Water can get into the module that does the calculations and that is invariably fatal.

Your tech must have zero idea about Suzuki outboard gauge systems if they went around swapping ecu’s to try to fix the problem…. If the ecu’s failed to the point that no data was sent, the engine would not run.

As a tech you will know the proven problem solving approach of …. Change one thing, then test. If problem persists, change next thing, test again. Rinse and Repeat until problem solved.

So, before just replacing an interface cable, start by

- unconfigure and reconfigure the starboard interface cable. Turn key on, in any SMIS gauge, select bus devices, scroll down to the starboard engine, select unconfigure, then when thats done, select configure and complete the configuration steps as prompted. You might also see an option there to reset fuel flow, cant hurt to do that too. Then test and see if that fixes it. Fuel flow at idle will either be correct or wrong, and if its wrong at idle it will be wrong at all rpm, so no need to test it at speed.

- checking the harness connection to the SDS plug on the engine. Given that things have recently been disconnected and reconnected there, look for loose or broken wires in the harness plugs, bent or corroded pins in those plugs or wires. Make sure the plugs are pushed firmly together and click into place. If you find loose or broken wires there is a tiny tab above the pins you can lift and then pull the wire/pin out from the back of the plugs, fix them, and push back in until they click into place.

- Then at the dash end, check the interface cable’s connection to the gauge harness for the same issues - loose or broken wires etc. As a tech, you know what to look for in that regard.

- Make sure that the connection of the interface cable to the network T is firm and tight.

- With the engine key turned on, check the black module in the interface cables. A hot module often indicates an internal failure and then you know it needs to be replaced, so leave the key on for a few minutes then check the modules, compare the problem side with the other interface cable.

There could also be damage to the harness between the engine and the dash. This can be harder to find but thee are potential failure points/joins/ etc where wiring can be damaged or connections get corroded.

If all that fails to solve the problem, the issue is likely to be the interface cable. The correct replacement version for a 2014 engine is Version 3.5.7 and its the current model that suits engines from 2013 until 2022. Available from Suzuki dealers. Plug it in, use the SMIS to configure it, set its location as starboard is all that needs to be done.

[FishTales]

Thanks for this valuable information. I'll let you know what I find out.

[FishTales]

Action Completed 06/01/22
Finally, was able to travel up to Port Clinton, Ohio. Upon arrival at the boat, checked electrical installation under/ in the center console. Visually checked connections adjacent to engine switches, NEMA 2000 devices and SMIS instruments.
Then as advised, I completed the Unconfigure and Reconfigure for the starboard engine/interface cable. With the first attempt no change was noted in fuel flow error indicated at idle. I then repeated the same procedure and found the starboard engine now indicated .4 GPH @650 RPM, which was the approximate indication prior June 2021. I still have a split in fuel flow between the engines at the dock in neutral .2 GPH less for the Port Engine. At 1300 RPM the split increased to .3 GPH. I repeated the Unconfigure and Reconfigure for the Port Engine, just to see if it’s indication would change any and it didn’t. When I get away from the dock, I will monitor Fuel Flow indications at higher power settings. Hopefully I won’t see higher split in GPH indications.
Both engine cowls were removed and ECU electrical connections and adjacent wiring visually inspected. No discrepancy was noted.
I appreciate your assistance with this digital technology. I’m an analog mechanic living in a digital world.
Thanks

[Moonlighter]

The fuel flow will almost certainly be affected by the same % variation at all rpm.

See the link below to the user manual for the SMIS gauges.

Check page 15, from the top of that page it tells you how to reset calibration (eg fuel flow).

Its possible, even likely, that the previous owner has calibrated fuel flow and messed it up, the interface will then have a incorrect equation stored. Resetting calibration will take it back to factory settings which gives you a clean starting point. I might add that most times the factory setting is very close to spot on.

From there, you can calibrate fuel flow at subsequent refuelling events to improve the accuracy to close to perfect. Page 44 sets out how to do that.

IMPORTANT: there is only one sure way to know if the fuel flow rate being reported is correct/true or not. And, that is to start with a full tank of fuel, go boating and burn a decent percentage of the tank (I would argue that at least 1/4 tank) then go back to the same gas pump, refill, snd compare actual amount taken to fill with the amount the Suzuki gauge system says has been burnt. You can then calibrate to improve the accuracy.

https://www.brownspoint.com/store/pc...nch_Manual.pdf

Just as a final note -
There can of course be minor fuel flow variations between engines of the same hp (which flows through to fuel used results). Partly its just that engine #1 is just running that little bit better from engine #2 for a host of reasons.

More often than not, differences in fuel used is MAINLY due to variations in the propellors!

Even though the props may be marked as identical sizes brand etc, when you get them scanned its extremely common to find that pitch can vary by an inch or more and that individual blades shapes can be quite different. Thats why many people with twin or triple engines get their set of props scanned, tuned and balanced to be as close as is possible to absolutely identical.

The result will be smoother quieter engines and any resonance minimised. And fuel used data close to identical.