Smartcraft issue or actually mechanical ?

[Korkie]

Posted this on mechanical as well. Not sure where it belongs, but here goes.
Sorry for the length, but want to give as detailed a description as could. 2006 340 496mags Br III drives - 900 hours. Bought the boat last year and has been doing great. Survey on purchase revealed only minor issues, mostly cosmetic. Approx 3 weeks ago started getting Fault code 40 on Strbd engine (MAT ckt lo) This started occurring intermittently than became constant. Checked manuals, stated bad sensor or short in circuit. Swapped sensors in motors with no change. Still getting Fault. Fault would occur sometimes at start up and sometimes not until after running for a few minutes. Also occur when reducing throttle coming off plane. (2 beeps / minute) It would also sometimes just stop and clear on its own.
Next came Port Fault 160 (Prt EMCT ovrht) at higher (3800-4000) rpms. Not knowing when impeller on that motor done, even though promised maintenance records at purchase, changed pump and impeller to Hardin Marine Gen 7 stainless pump. Took out, same problem. Since indicated exhaust manifold ovrht, took hoses off both manifolds and found one side partially obstructed with soft mud. Flushed manifold and fitting (on bottom) as well as could and re assembled, hoping that was problem. Also, last season, I completely removed and cleaned heat exchangers on both motors. Took her back out. Still getting the Fault 40 MAT, pretty constant on start up now. Up on plane with usual power, gauges all normal, cruising at 3500 or so, all good. Then took her up to 3800-4000 and OMG alarms went crazy. I got 11 alarms within 1 minute, with several sounding at one time. Power went to idle only. After several minutes of idling, it would let me apply throttle and I actually got back up on plane for the short (1/2 mile) run to my creek. The other thing that started shortly after the MAT FAULT is that when up on plane at 3500 or so rpms, the STBD motor rpms would decrease to about 3150 or so for 15 - 30 seconds and then go back up to 3500 only to drop down again and go back up, continuing this throughout the run. Also, came down off plane one time and on putting into creek at 1000, the STBD motor hadn't thrown the MAT fault, but then it increased its rpms to 1250 and threw the fault at the same time.
Once back on lift, history showed this list of faults: STBD FAULT 210 - Neutral overspeed / STBD FAULT 160 - prt emct ovrht / STBD FAULT 179 - stb emct ovrht / PORT FAULT 179 - stb emct ovrht / PORT FAULT 9 - Guardian / PORT FAULT 19 - overspeed / STBD FAULT 19 - overspeed / PORT FAULT 160 - prt emct ovrht / STBD FAULT 9 - Gaurdian / STBD FAULT 40 - mat ckt lo / SYSTEM VIEW FAULT - ambient temp ckt Hi.
With all of that, my STBD motor wasn't giving me any issues at all before cleaning out my PORT motor exhaust manifolds. All of the STBD ovrht, etc fasults were new as well as the ambient temp fault.
Been researching through the forums, and only info I can find is members having similar issues and it was actually the Smartcraft throwing false faults. I also read that some fixed it with a SMARTCRAFT SENSOR RESET, but cannot find any info as to how this is performed. Did see some did a total system reset, but want to stay away from that if possible since seems to require some re calibrations, etc. I live in an area where there is limited Mercury techs / marinas, so they are backed up with a 3 week wait just to get in.
I have had input from several sources and in addition to the new port raw water pump and cleaning the port exh manifold I tried swapping the throttle position sensors, no change in rpms variation. Stayed with STBD motor. Changed the MAT (new), also no change. I checked, cleaned and tightened my grounds last season, will do that again, but they looked good visually.
Any insight / direction on things I can do to troubleshoot, etc while waiting for the tech to come available would be greatly appreciated.
I am usually a pretty good detective figuring these things out, but this one totally has me baffled.

 

[Bt Doctur]

hold the plus and minus down for 5 sec and it will do a master reset - you will lose all your settings and have to recalibrate per the manual

 

[Bt Doctur]

https://dmna.ny.gov/nynm/manuals/Mercury_SmartCraft_Operations_Manual.pdf

 

[Korkie]

I don't have the Smart craft info on the gauge type I have the System view in the dash - Version 3.44. My dash gauges are just regular needle type gauges.

 

[paulswagelock]

Most of the symptoms and alarms are in line with the manifolds overheating. Are you in brackish or salt water? Sounds like bravoitis.

 

[Korkie]

Brackish /salt - yes - the lower Potomac river. Boat came from upper Chesapeake. Bravoitis?

 

[paulswagelock]

Bravoitis is a bravo 3 condition where the water fitting in the outdrive closes off due to corrosion limiting the pump ability to draw in sufficient water. It causes symptoms similar to many you are describing. Do you have the ability to display water pressure on your smart craft display?

 

[Korkie]

yes I do. What should they be reading at idle and say 3500 rpms and 4000 rpms? Last year my Port motor was reading really high, so I took off the heat exchangers and cleaned them. Both motors then ran at same numbers (psi) and I had no overheat issues. Motors at 165 degrees at idle and 175 or so at WOT. I did see recently that the Port motor seems to be lower than usual and the stbd motor is higher - like 15.9. I will take boat out and document some numbers and report back. Thanks for your help troubleshooting this. I have had Mercruiser / Bravo III drives on my boats for the 15 years and never had anything like this happen. Then again, I have no idea what condition the innards of this boat other than what the gauges were telling me at sea trial.... and all has been great up to now.

 

[skibum]

Korkie, I think you have a very simple problem that will be hard to find. To answer the thread title, "mechanical". I put it in quotes, because I'm betting on a loose or corroded connection. As you said, either the Smartcraft system is fried, causing the bogus alarms to be displayed, or SC is fine, and something else is wrong. I believe it is the latter and SC is fine. With that many alarms at once, it must be something that all of the sensors have in common. The main thing that they all have in common is the power source. They all use some mechanism to modify a reference voltage based on what it is sensing so that the ECU can determine the proper reading, which SC displays. The first thing I would do is verify that I have a good solid 5 Vdc on two or 3 of the sensors. You should be able to do this key on engine off. If the sensors don't have a good 5v reference voltage applied to them, then they all would be presenting the wrong information to the ECU, and it is properly reacting to the information it is getting. The harness(es?) that connect everything together also have ground wires. A bad ground to the sensors will also cause the same situation even if the sensors have a good 5v. It will behave the same as if the 5v were too low.

Hop in the bilge and go through every connector on the engine harnesses one by one. Unplug each one, verify that all of the pins and sockets are clean and present (sometimes, the individual pins or sockets can work their way out towards the back of the connector and need to be pushed back in), and then reconnect them. It sounds like a loos harness connection to me. You'll never see it, so you have to touch each and every one in order to find it.

 

[paulswagelock]

As a reference, water pressure should be .9-1.5 at idle, 12-15 psi mid range and >16psi wot. Each boat is different but these are typical for a clean system.

 

[Korkie]

skibum - how do I know which wires at the sensor plug are supplying the 5vdc, just hook to a common ground and touch them all to see if at least one has the 5vdc? I did check all of my grounds, they are clean and secure. I did not check the crimps, but they all seem tight and secure when tugging on them.
Just got in off a test run to get pressure readings for paulswagelock, so once it cools down, I will attempt what you suggested.

paulswagelock - went out for test run. Here are the stats - so to speak. At start up, got the usual fault 40 MAT ckt lo, port engine psi @ 1.8 and strd engine psi @ 2.0 - @ idle. Motors both warmed to 165 port and 160 strd. Going out creek, which has soft muddy bottom and only 4 ft at low tide, @ 900 rpm - port psi @ 2.8 - 165 degrees / stbd psi @ 3.4 and 160 degrees. Out of creek and up on plain, usual power / time to 3500 rpms - port psi @ 8.8 temp 168 and stbd psi @ 16.2 and 167 degrees. This maintained for several minutes. Took port motor to WOT (4250) - psi 10.2 and temp 176, maintained this for short time before getting FAULT 160, port/port em ovht fault, back 3300 for the port motor. Then took strb motor up to WOT (4250) psi @ 19.2 and temp to 177. After short time (2 min?) got the stbd FAULT 40 MAT ckt lo and at same time went into Guardian at idle power only. Off plain and both motors to idle. Port responsive - stbd, guardian wouldn't let it accelerate above idle. Shut down stbd motor and restarted, back to just the FAULT 40 and full power both motors. Still had the up and down issue with the rpms on the stbd motor as well. Voltage showing high o n both motors, 13.9 port and 14.2-4 stbd, they are both usually at 13.8. This has been happening right along with all of this.

 

[scoflaw]

I use a sewing needle attached to a volt meter and back probe the plug at the sensor. A chaffed wire or a bad sensor can draw down the voltage and possibly effect some or all of the rest of them

 

[skibum]

skibum - how do I know which wires at the sensor plug are supplying the 5vdc, just hook to a common ground and touch them all to see if at least one has the 5vdc?

Exactly. If you see 5v on any wire on two or three sensors, you're probably okay. Another thing you can try with the engine running is to jiggle the harnesses at various points to see if you can make the alarms go off.

 

[Korkie]

I did the jiggle test one on strbd motor when I was just dealing with the MAT fault by itself. No results. I will do the 5v test next to see what that brings. Will one bad wire affect both motors sensors ? Thanks, K

 

[paulswagelock]

Might be two different issues going on. The port motor is low on water pressure, that is close to the readings I was getting and had the same overheat alarm you have. Bravoitis was the problem. New water tube and press in fitting in the lower unit and no issues for 2 years. Not sure on your starboard side.

do you have the flush hose/ port on your motors? If so, there is a simple test to check if the lower unit pick up is the restriction.

 

[Korkie]

No, don't have the flush hose port, but may have them installed as would be nice to flush motors after weekend of use. I did back flow with a 50 psi hose when I inspected and cleaned the manifolds on that motor. I do agree may have 2 issues going on. Going to go over both motors and recheck grounds (and crimps) and the voltage at the sensors as previously mentioned. Guess gonna have to pull her to check the lower units unless you know of another way. The boat is kept on a lift. So having the drives out of the water to do things other than remove them is doable.
All of the issues with power (rpms) varying and the MAT code and one time faulting with ovrht exhaust man has been on the stbd motor.
Back to the hunt. :smt017

 

[Korkie]

Finally got to the bottom of this. The Fault 40 MAT code was due to a bent pin in the harness connection at the motor computer. Once on the diagnostic computer, could giggle the harness connection and watch the volts to the MAT sensor fluctuate all over the place. Traced the respective pins and there they were, just ever so slightly out of line. Carefully squeezed and straightened and fault gone (so far). With the overheat issue, Bravoitis for sure. Removed the hosing going through the stern and OMG, what a mess. 50 - 60% blocked due to collapsed tube. Went with the addition of through hulls and Ts from the outdrives. Boat now runs no hotter than 168 degrees, even at WOT. Will clean up the outdrives and change out the hoses next regular outdrive service. Kudos's to Coltons Point Marina for their help and impressive work.