Every time i take my boat out it will run great with no check engine light coming on for an hour or two. Then intermittently the check engine light will sound and then eventually go off. The engine runs fine and doesn't seem to change its behavior in anyway when the sound alarms. It happens at higher RPMs as well as lower RPMs. It seems to go off more frequently once it starts happening. its been happening for 3 years now and its driving me nuts!
Things i've done:
Replaced fuel tank and check valve (not for this issue, it had a hole in it)
Replaced fuel filter
Replaced all fuel lines leading up to the engine
Replaced fuel primer bulb
Replaced thermostats
Replaced water pump
Added a fuel filter and water separator
Replaced VRO
I also just installed a new Tachometer with Johnson System Check, but i haven't tested to see if that impacts it in anyway yet.
Additionally i have a 3 gallon gas tank i was going to try and hook up to rule out any tank or check valve issues.
What else could it be? Or what else could i try to replace to fix this check engine light?