"Engine Data Bus" error and engine cuts out

[seattlesearayer]

Hi there. Have a 2004 SeaRay Sundeck 220 with a Mercruiser Bravo sterndrive in it and it's been trouble-free for 14 years. Just this season, some weird stuff started happening. Doesn't happen every single time we take the boat out, but it's happened 5 or 6 times now and we've had two shops come out and try to reproduce it and they haven't been able to. Basically, we'll take the boat out for a few hours and then when we get back to the marina and start taxiing at very slow speeds, we'll often get a single beep with the error "Engine Data Bus" on the gauge. Sometimes this will be followed by an engine stall and sometimes not. Until today, when it would happen, we could always start the engine right back up. However, it happened today *right* as we were pulling into our slip and the engine cut out and would not start again. Tried for several minutes and the engine didn't move at all.

Any ideas?

The weird part about this is that every time it's happened, it's been right at the end of the trip. I've tried to run the boat at as slow speeds as possible at various times in the middle of trips just to see if I could reproduce and it never seems to happen. Kind of makes me think it has something to do with how long/hot the engine has been running. Temp gauge at the end of the trip today when it happened said 150 degrees so nothing out of the ordinary there.

 

[achris]

Hello seattlesearay and :welcome: to iboats.

We need to know what engine you have, preferably with a serial number. 2004 Searay Sundeck 220 tells us nothing of the engine. Mercruiser Bravo also, tells us very little.

Engine make, model, year and serial number. If you have a drive problem, what sort of drive (there's 9 different Bravo drives)

"Engine data bus" does tell me it's likely to be MPI, and they run CanBus (NMEA2000)...
Did either of the 2 shops connect a diagnostic computer and check to see what codes had been set? (I suspect not :facepalm

Strange as this may sound, is it possible that it's only happening in the one place because of external influences? You have a smartcraft instrument (that's where you're reading the error), so you have a canbus data cable running from the engine to the instrument panel... If there's a high power radar or something similar in the local area, then they can interfere with data signals....

Firstly, you need to find someone to connect up and read the error codes from the engine...

Chris.......

 

[seattlesearayer]

Ok, I'm an idiot. Just went down to the boat this morning and it was still in gear, and that's why it didn't start back up. Duh. So at least this incident isn't any different than when it's happened in the past: engine data bus error, one beep, engine cuts out, and then starts back up again without problems. Still need to find out what's going on though.

To answer your questions:

Serial #: 0M658186
Engine Model #: 4-M42037RS
It's a Mercruiser 5.0 MPI

The first shop we had came out did not have the proper diagnostic tool, but when we called the SeaRay dealer, they did. No error codes were displayed.

Really interesting about the radar interference bit. Would have never thought of that.

 

[dingbat]

If there's a high power radar or something similar in the local area, then they can interfere with data signals.

It’s going to take one heck of a radar beam to interfere with a CANbus communication link

It’s a differential link. Pretty much immune to electromagnetic interference. Reason it’s used extensively in industrial automation

 

[dingbat]

...

 

[Scott Danforth]

most likely there is a connector issue with the can-bus backbone wiring. there are 3 wires... TX, RX, and ground. there is a 120 ohm resister at every branch end in the wiring.

lose a resistor and the CAN network goes down
lose a connection and the CAN network goes down

 

[achris]

dingbat It only does it in one place. OP has attempted to replicate going the same speed etc, to no avail... Please, explain...

 

[seattlesearayer]

Update: Just took the boat out of the water for the season and it happened again, this time away from the marina. So we can eliminate the marina as a possible culprit. Once again though, it was at the end of our journey. So the common thread here is it tends to happen after the boat has been underway for at least 45 minutes or so. ¯\_(ツ)_/¯

 

[achris]

Loose cables. Also check you have the canbus termination resistors on BOTH ends of the canbus backbone.

Chris.....