DF140 - neutral switch functionality

[Helgeo]

I have a 2011 DF140 with 90 hours on it. Sometimes it refuses to get more than 4000 rpms, and sometimes it refuses to start. I have two steering positions in my boat.

When it refuses to get more than 4000 rpms the problem is solved by switching to neutral, then stopping and starting the engine.

When it does not want to crank the engine, shifting in and out of gear a couple of times will fix that.

I believe that both the motor and the remote control(s) have switches to detect that the motor is in neutral.

The neutral switch has two purposes:
1) Prevent the motor from over-revving when not in gear
2) Prevent the motor from being started when in gear

Are both these functionalities controlled by the same switches or do they have separate circuits?

I assume that both problems are switch related, any other ideas?
Which switch is most likely to be causing my problems?

Thanks!

[Moonlighter]

Look, I wish I could answer with certainty, however......

I have been having a very similar problem with my 2009 DF 115 Suzuki. Same engine family as your 140.

The one where you start the engine, put into gear, but it refuses to accelerate normally and won't get full power, nothing more than about 3000-3500rpm. Stop, shift to neutral, turn off, wait a few seconds, start again and it then runs perfectly. Same as what you described.

My mechanic and I considered many things and checked lots of things, the ecu showed no codes on his laptop using the diagnostic software. We checked all electrical connections and fuel lines, filters, etc. everything was fine, even the fine filter in the vst.

At one stage, the problem occurred so regularly that I would turn the key to the on position but not start the motor, turn it off again, then turn it on, and start, it then went perfectly every time I started it using ths procedure.

He believes that it is a fuel related problem. A couples of months ago, he changed the fuel regulator as he thought that it might not be seating properly, therefore losing fuel pressure. He believed that restarting when the problem occurs runs the electric fuel pump again and re-pressures the fuel system.

The only other thing we changed at that time was the fuel bulb in the fuel line. Put a new large OEM Suzuki one on.

Well, so far, I've done another 8 hours running and the problem has not recurred.

So, have a talk with your mechanic and suggest this.

Like you, I thought it might be the neutral switch, but perhaps not, given my experience. But it's only been 8 hours running, so not 100% sure we have solved the problem yet, but it looks promising.

Where are you located? I am in Australia, my mechanic is Jon Eadie, Bayside Suzuki Marine. You can get his contact details from the Suzuki Australia outboards website if your tech wants to discuss with him.

He did talk to Suzuki head office and noOne else had reported similar problems, so they couldn't help. Seems like its just you and me!

Cheers

ML

[Helgeo]

Thanks for you answer Moonlighter, I believe we have discussed the NMEA interface for these motors over on The Hull Truth - Boating and Fishing Forum a few months ago?

I'm located in Norway, so quite far away from you.

I have googled this problem extensively and found a few similar cases, some have been fuel related and some have been neutral switch related. And some have just been solved without the owners really knowing what fixed it.

At least one person wrote that the problem was caused by the fuel primer bulb being collapsed. That should be possible to check by inspecting it while the engine is still running after this problem has happened.

As I have the Suzuki NMEA interface I do get fuel consumption readings on my Simrad plotter, interesting thing is that when the rpm-limiting problem sets in the fuel readings go extremely high. Consumption can be close to 40 liters/hour at less than 4000 rpm. Did you experience the same thing?

One thing that just struck my mind is that the wire for the NMEA interface (SMIS) runs alongside one of the fuel lines, perhaps that could put a small restriction in the fuel flow? Maybe just enough to create this problem every now and then.

My motor is still under warranty, but since the problem is intermittent I feel it could still end up being costly to take it to a service shop if they cannot find anything.

Regards from Norway,
Helgeo

[redlowrey]

It will be the neutral switch on the motor, it might be loose. If the ECM see's an in gear signal on crank there will be no starter and no fuel injection pulses, and if it see's a neutral signal when it is in gear it will keep the revs to 3000 rpm and timing fixed at 8 deg.

[Moonlighter]

Hi Helgeo

Yes, I think we have talked before on THT re NMEA interface. They work great, hey! Especially now that Lowrance have fixed the calibration equation for those of us who use litres! My actual fuel used and what the network reports are now nearly always exactly the same. Very accurate indeed!

I have never looked at the fuel flow data when the problem occurs, very interesting observation you have made there. If it recurs, I will check.

It also makes me think more about the neutral switch still being a possible culprit, as what redlowrey says would be consistent - no advance when accelerating would probably cause fuel consumption to increase. It actually feels like that is the sort of thing that is happening. It sounds very logical and plausible to me.

Like you I also thought that the NMEA wiring running beside fuel lines might be a possible cause, but it doesn't seem very plausible when there are so many other wires also beside the fuel lines plus the NMEA cable carries very low amps, just some data signals. Very unlikely to affect fuel lines I think.

One thing I did notice last weekend - we were away for a 3 day fishing trip and had the boat on the water 3 separate times, and the new fuel bulb stayed noticeably firmer than the old one did. The problem did not happen once, we must have done 50 drifts and started the engine as many times, and it performed flawlessly. However, we have thought previously that we had it fixed and it subsequently recurred.

Redlowrey:
Thanks heaps for chiming in. Really appreciate your thoughts.

Can you give us a bit more info about the neutral switch- when you say it could be loose, what exactly do you mean and how could it be fixed? - is it a replacement job, or simply tightening something, such as a wire connection or something like that?

Is this issue something you have experienced or seen previously and was solved via doing something with the neutral switch?

Where exactly is that switch, so I can have a look at it?

Really appreciate your further thoughts on this.

Cheers

Grant

[Helgeo]

Grant,
Thanks a lot for your comment about the software upgrade for our plotters, that made me just find the new v2.0 upgrade for the Simrad NSS. Will install it tonight. I have not been able to use the calibrate function up to now, as it would always completely mess up the fuel figures.

When talking about the NMEA cable running alongside the fuel line, I was thinking that it might physically interfere with the fuel tube, creating some kind of restriction. But the cables are very thin and the fuel tube is very stiff, so it seems unlikely.

The neutral switch is still my prime suspect, but not ruling out other possibilities yet.

Redlowrey: Thanks for your comment on the switch on the engine, will inspect mine and see if there is any evidence of misalignment or other signs of why it would fail occasionally.

Regards,
Helge

[Moonlighter]

Hi again Helgeo

Great to hear that they have updated the NSS software too. I am sure they will have applied the fuel calibration fix. I had to calibrate 3 times, and since then it has been perfect.

Where do I find this neutral switch on the motor? I want to have a look at it and see if there is anything obvious that is loose etc.

By the way here is a pic of a great snapper I caught on the trip last weekend, a new personal best, caught on a soft plastic lure, it weighed 11 kg, caught on 10 kg braid line.

http://i729.photobucket.com/albums/w...1kgupload2.jpg

Cheers

Grant

[Helgeo]

Hi,
Here is some more info on similar problems, also a couple of pictures of the neutral switch:
Help need information-Suzuki DF140 motor problem

Nice catch, not a fish that we can get in Norway

Regards,
Helge

[Stonka610c]

Gents, I know this thread is a bit old now but hoping you may have an update as to whether this issue is resolved. I have a 2011 DF140 that has had the same fault almost from day one. Exactly as Helgeo described, won't rev past 4000rpm and fuel consumption on the readout doubles. Bring back to neutral, switch off and restart and all back to normal. Has done it from cold (rare) but generally after being stopped for awhile and restarting as with drift fishing. On a few occasions when throttling back to restart it it will stall or idle very rough, the over fuelling I suspect.
I am an ex-automotive service manager and tech, and have thought it to be ECU related from day one due to the fact it never sets a fault code. Found in the auto trade similar intermittent faults that did not log a code most often led back to an ECU fault. To date we have replaced MAP sensor, NMEA cables, re-routed wiring and checked the fuel system to death. No luck. The neutral switch sounds like the most sense yet so keen to know if anyone has finally had success. Cheers