Weird starting issue

[I_do_WRK86]

Boat is a 2012 242
Last weekend I took the boat out and got a CEL (port engine) on my way out to our local beaching area and it stayed for the whole ride back (about an hour both ways) but had no issue with power and no issue starting the boat until I got it on the trailer. I had a bit of a vibration issue but nothing serious. I turned the engine off, it never shut itself down. I'm currently in the process of changing my intermediate bearing and wear ring (other issue that needed to be fix), but first I'm trying to work out a starting and bad idle issue on my port engine.

As it sits right now it is cranking strong; turn key, comes off starter, idles for less than a second and dies on first try. On the second try it cranks but it doesn't come off the starter. I can let it wait for a second (key in off position) attempt again and it will act like first cranking attempt. When it does act like the first attempt I can catch it with the throttle and it responses without any issue, but when I pull the throttle to idle it vibrates a bit excessively but smooths out and will stay running(CEL still remains). IDK if there is a limp mode or how it acts in limp mode (no throttle limitation/no power loss, planed like normal). Starboard engine has no issue at all.

Things I've worked out/changed
1) Spark plug
2) Fuel lines clear
3) Fuel pump works
4) compression is fine (all around 160) 200 hrs on engine
5) changed oil in April this year

Thing I haven't worked out yet
1) The CEL
2) Any more Fueling issues (pressure , injectors, etc)
3) Timing (doubt it slipped a tooth/ personal experience with other engines)

 

[I_do_WRK86]

Something else I wanted to add was that the plugs definitely looked black almost carbon fouled but IDK if that was because of a limp mode slamming fuel into the cylinders. It definitely smells like its running rich. It was kinda hard to tell tho because it wasn't starting so I removed the plugs a couple of time so it didn't lock the engine.

 

[FSH 210 Sport]

Sounds like it needs a code reader to determine what’s going on.

 

[Hot2Go]

When exactly did you change the spark plugs? as soon as the problem occurred? Agreed with above that you need a code reader for sure. What RPMs are you at while idling when you get it to fire it up?

 

[I_do_WRK86]

When exactly did you change the spark plugs? as soon as the problem occurred? Agreed with above that you need a code reader for sure. What RPMs are you at while idling when you get it to fire it up?

It (brand new plugs) was the first thing I did when I got the boat to the house and started trouble shooting. After I get it started (with the throttle input) it idles like normal around 800 rpms. If you ever messed with larger cam carbed cars that's the process it reminds me of (throttle to start, wants to die when it comes back to idle, idles fine). Yea I'm temped to take it do Yamaha to have them read it or buy Candoo/YDS.

 

[Hot2Go]

The starting issue definitely seems its either fuel, air, or spark; which you've ruled out spark/fuel, can't imagine it's the air filter, but maybe it is a bad ignition coil? You can try swapping ignition coils from the good engine to the bad and see if it changes anything? Definitely need the code read to determine though, and you can run more tests using the software.