Suzuki 2012 140hp issues + dual battery wiring

[Bee888]

Hi Guys,

I'm hoping someone on here can help me out.
I have an odd issue with my Suzuki 2012 140hp.

To give you some history, i first installed this motor second hand last year. Initially, I had issues with it stalling everytime i decelerated and came back to neutral.
When I purchased the motor, I knew it was a clean good motor, and had a diagnostic done, no issues, alarms or any problems detected.

I raised a thread here and some kind fellas posted replies, mainly pointing towards IAC as the cause.
As we were in lockdown at the time (Thanks Gladys) I couldn't take it to a dealer to check it out.

I ended up replacing the IAC, and then re-set the idle speed. My issue's got better but was still stalling at times.
After this though, I realised the IAC was likely not the issue and focused on the setup, I ended up replacing the throttle cables as mine were old, to some nice new premium ones, re-setup the CTP switch at the motor end by using a continuity tester and changing the turn buckle on the throttle cable to match the manual. After this, my stalling problem went away!

The motor has been running fantastic, but did occasionally end up with the odd stall here and there.

Fast forward some months and my stalling begun again, but very very random. Out of say 10 times out, it would do it only a few times. In low idle, either say backing away from a wharf or powering up onto the trailer etc. At times here and there it did stall when decelerating.

As it was so random and intermittent i knew it was going to be hard to have a dealer diagnose, so i put up with it.

Now though, a new issue begun - in the last 3 times I have been out, It randomly wouldn't go over 4000rpm. No diag lights, no alarms etc.
Hammer all the way down and 4000rpm was the max, it felt sluggish and had no power as if a rev limiter was kicking in. To fix the issue when I am on the water, i simply pull back to Neutral, power off and start up again - Wam back to normal and get rev it out and motor is running amazing again. I should also add in idle sometimes i hear a weird sneeze/sputter from the exhaust.

Since it was fixed with a shutdown, I am inclined to think this is being caused by an odd issue.

I've had a chat to a couple dealers, and am planning to take it in for a professional to put it on the diagnostic etc, however everyone is busy atm - I'm looking at a 4 week wait atleast everywhere.

One dealer mentioned I should check my battery connections, + white wire for any corrosion while I wait till they can slot me in.

While waiting for a dealer to see it, I have now done the following:

- Replaced Neutral switch in binnacle - no fix
- Checked and clean all batt connections.
- Checked white switch wire - no breaks, corrosion.

This now leads me to the reason I am posting, I think my current setup with dual battery system may not be ideal and possibly causing these issues for me.

I have:

A Standard 30amp battery switch, with Both, 1 , 2 and OFF functions.
My white wire is connected to the Common on switch
My outboard positive wire is connected to the Common on switch
Batt 1 has nothing connected to it - starter battery and + is connected to 1 on switch
Batt 2 has some accessories connected to it.
Switch panel etc go to Common on switch.

When running, I usually have it set on "Both" all day.

I think, it should be done as the following:

White wire connected to + on starter battery
Outboard + connected to + 1 on batt switch
1 on switch connected to + on starter battery

Accessories on Common

2 on switch connected to + on house battery
and accessories connected there
switch panel etc on common through bus bar.

I am just trying to eliminate all the pesky, easy things before it goes to the dealer.

Do you guys think the current battery setup is possibly causing low voltage or spikes to the ECM and causing my problems?

Any help will be appreciated, apologies about the LOooong post.

[Moonlighter]

Low voltage/poor connections are usually accompanied by multiple false fault codes. They dont show in the ecu record but show on the gauge. You haven’t mentioned that?

I think its just as likely to be fuel supply related.

You stop the engine, then turn the key on and the LP pump runs to re pressure the system…

…. and that might cause blockages in the VST to shift and allow fuel to flow more freely for a while again….. or it might temporarily compensate for an air leak in a fuel hose/primer bulb.

- Has the high pressure filter on the engine even been changed?
- primer bulbs are notorious for failing, must be pointing upwards too. Check clamps either side and the condition of the hoses under the clamps. Prime it to hard and see if it holds pressure.
- fuel lines with an air leak - anywhere between the tank and in the engine under the cowl where lines connect to filters etc. So, again check the hoses under the clamps, if any doubt at the very least you may be able to cut off a couple cm and reconnect with clean hose on the barbs
- running a Racor style fuel filter? Change the element.

The other simple thing to do is change the spark plugs, one bad plug can cause rpm loss at speed but be hard to feel it at idle/lower revs.

[artdf175]

many of the symptoms you describe I was having..
The stalling for the most part is the IAC valve . earlier had the cutting out problem being caused by a butt-end connection that had literaly corroded.

the problems with the 4000 RPM situation is voltage related...
the ECM on these engines is very sensitive to the correct voltage. In my situation a good digital tester the will measure your RPM's and show you fluctuations helps. mine was jumping all over the spectrum.
My lowrance was getting multiple alarms, rpm's jumping from 0 to off the top. my case was the white wire voltage issue. I wrote the Sticky regarding the white wire several years back.
this time I was doing some rewiring and off the battery switch inadvertently spliced in an undersized wire between h the battery and the white wire.. what a disaster,.. Rpm's all over the place, overheat errors several more checked them out and only could find lower voltage at the key switch.
fixed the undersized wiring and the problems are gone.
Art

[artdf175]

Moonlighter- turning the key off resets the ECM. and it will run perfectly until the rpm' go off the chart again

[Bee888]

Hey Moonlighter, Correct - havent seen any low voltage issues on my gauges.
I run multiple devices and on my Garmin sounder I see a healthy 14.7v +- charge while running, and batteries sit around 13v when off.

The high pressure filter was replaced last year when we mounted on the motor, although I do see one of the hoses on it is held by a cable tie only?

I just checked the fuel bulb, goes hard when i pump it but after a few mins sitting I can pump it a few times gain. It isnt completely empty or collapsed, but i can squeeze it a few more times and feel it go hard again. Tested this for a while, same thing. Ive just gone through and had a look at all of the fuel lines from the tank to motor, cant see any leaks.

From what I know the bulb wont always stay completely hard, since its low pressure fuel and it will settle again after being pumped?.

I realise now the service was done 9 months ago, only 34 hours run time since though.

I do have the SDS interface cable connected to my Garmin sounder
In my research I found a post you had mentioned the red wire was the cause of low voltage sent to the ECM putting causing the rev limit issue.

I wonder if this is my cause?, thinking about testing the theory by unplugging the cable and going for a run?

[Bee888]

artdf175 Thanks, ive checked my white wire, i also spliced it and extended it a while back, but I used same size tinned wire.
I have now cleaned up it again and fit it directly to my starter battery pos terminal.

I havent seen any issues at all with my electronics, gauges etc accompanied with the rev limit issues I am having.

[Moonlighter]

You can try unplugging the engine interface, but that wont be the issue - my old post was very specific - the engine went into safe mode and wouldn’t rev past 3000rpm. You said that yours gets 4000rpm when it has the issue. So thats not the issue.

So did you just look at the fuel hoses, or did you undo them and properly check their condition under the clamps? Be thorough.

And yes I would replace that zip tie with a proper hose clamp.

At this stage my money is still on fuel issue. Eg contamination causing a blockage, or an air leak. Second choice - a bad spark plug, changing them isnt that expensive, and we do occasionally see reports or new out of the box plugs that are bad. If you replace them and thats not the issue, you can always put the previous ones back in or keep them for the next service.

Has the VST ever been inspected and cleaned out? Theres a tiny screen filter in there - if it blocks up then Ive seen many reports here on the forum of rpm problems much the same as yours.

[Bee888]

So, un-plugged the engine interface and took it for a run yesterday afternoon, issue didn't occur. Motor ran great the whole time.
Tried multiple times with turn off, sit for a while, restart and go etc and had full RPM all the way through. Could the fact I get 4000rpm be due to the way the boat planes, is propped etc?

When i checked the fuel lines i pumped the primer ball hard, and sprayed soapy water on the connections i could see everywhere, looking for a small air bubble etc.
All the hoses in side under the cowling stayed nice and hard and none showed any leaks - even the cable tied ones.

Now I'm also taking it with a grain of salt, as my issue was intermittent, however the last few outings as I had mentioned it did happen everytime.

I too think it could be something else lurking, blocked VST, filter etc.

I don't know the history of VST ever replaced, however i do know the guy i bought it from was very thorough when looking after it.

I plan to do the following now:

- Plug the engine interface back in and test again hopefully this afternoon and see how it goes.
- Check fuel lines more thoroughly, and replace any cable ties with clamps.

The water sep fuel filter is about 1.5yrs old, so ill get that changed out.

My dealer has just called me and advised it can come in now, so I think ill drop it off and ask them to go right through it, check fuel system for any leaks, service it - repl plugs and check/clean out VST.

Regarding the engine interface wire - is there any known problem with re-wiring the red wire direct to batt just incase?
And if so, should it be fused and direct to the house batt?

[Moonlighter]

I simply pulled the pin for the red wire in the SDS Adapter cable at the engine end - that removed the ecu power source to the interface cable, and then at the dash end of that cable, tapped into the red wire in the adapter cable and wired it to a switched + source.

3000 rpm is the “safe mode” rpm that is set by the ecu. Nothing to do with load etc. also, in safe mode, the ecu restricts spark advance and fuel, so when mine had the issue, as soon as I started to accelerate I know the issue was happening because it was very doughy.

What make and model boat do you have?

[Bee888]

Ok, yeah I read that in your post.
I can easily do that and wire the red cable from the plug behind the dash straight to a positive bus bar I have there, that goes to my Common on switch.

I'll test the boat more with and without the SDS plugged in before making the change.

When I lose power, i can also tell instantly.
It just has nothing at all, usually from 4k beyond is when I feel the motor power kick in and scream off, when the issue happens as soon as I start to accelerate its also very doughy.
I have a video on my phone I can send you if you'd like to see what happens in real life.

Boat is a Haines Signature 542f.

[Moonlighter]

The other thing is that with the rpm issue I had, we though it might have been the neutral throttle switch ON THE ENGINE. That is the one that limits rpm until it sees that the engine is in gear.

Its on the gear linkages on the starboard side and can have intermittent issues. However when my dealer hooked up the SDS computer he could see that switch was working correctly when the engine was put in and out of gear. A physical inspection also confirmed it wasn’t loose or broken.

I went back and re read your first post.

You replaced the wrong neutral switch.

The one in the binnacle prevents the engine from being STARTED in neutral. Its the one on the engine gear linkages that prevents it being revved in neutral.

Find and inspect the one on the engine, it can just get gummed up. Otherwise its not an expensive part so replacing it might be just as easy.

[Bee888]

Sorry about the long delay in replying. Boat went to the dealer, and they seem to have sorted the issues.

They found the following:

- Red wire at SDS cable they also believe was cause of the rpm limit or could become a factor. This was chopped and re-wired to positive post behind dash.
- One injector fuel flow was a bit low. 3 were ok but all 4 were sent off for a clean and all flow now equal.
- Couple white wires on ECM harness apparently had corroded, (no idea what they were or what this would have caused) They fell out when they pulled on them. So these were replaced.
- Thermostat had seized open, causing motor to always run cold.

Seems like there were quite a few niggly issues missed in the last service.

They fixed the above, and then re adjusted idle with SDS diag, came up a little bit.

Testing so far has been really good, motor ran beautifully and no issues at all.
No stalling or RPM limits.

I'll keep running it for now and test but I think they have sorted it.

Thanks for taking the time to help with these issues.

[artdf175]

I just found your post. besides the maintenance issues that should have been found with regular yearly servicing.
IT WAS THE WHITE WIRE!!!
These engines need 100% voltage - all the time..
corroded connection as I wrote about in he sticky is a huge problem
Glad you are back and running
Art

[Bee888]

Hi Art,

It wasn't the white sub wire we connect to batt +
That was checked and was all ok - no corrosion, good solid connection and moved to + post on starter battery just incase.
I was still having the issues even after confirming this was ok.

The corroded wires they did find were on the harness that connects to the ECM.
No idea what they do exactly, but obviously would have been causing weird voltage/signal issues etc.

If they in-fact somehow match up to the sub white wire, dunno, maybe someone has an ECM diagram they can verify.. but yes they were 2 white ones in the pictures I was shown.

[artdf175]

Did you happen to find the "sticky" page?
https://www.suzukioutboardforum.com/...-power-failure