Mercury 30hp 4-stroke sometimes won’t start

[Risto1234]

Hi!


I’ve recently run into some engine issues, hopefully someone of you has some advice.


The engine in question is a Mercury 30hp 4-stroke from I believe 2015. With electric tilt and electric start. Approximately 400h of usage, mostly trolling at idle speed. Serial number #OR668621


To the problem. Twice it has happened that after running the engine for a approximately an hour, stopping for fishing a spot. Trying to start the engine once more, it started for a short while, dying and refuses to start again.


Both times resulted in a shorter than planned day on the water and both times it started, as nothing had happened, again when I had towed it back home and tried starting it on land with the garden hose attached to the engine providing cooling.


Hard to do a complete search for the error when on the water. But I could see fuel reaching the fuel filter when pumping the balloon on the fuel supply.


At home I have checked the fuel filter and it is clean and lets the fuel pass through. The spark plugs are almost new, below 5h of usage. I charge the battery between trips so it should be ok as well.


I’m leaning towards an fuel issue as it started up and then quickly died but I’m not sure where to look.


Any help would be greatly appriecated!

[EuropeanAM]

Need to determine whether it's fuel pressure loss OR spark loss.

A timing light can be carried out with you... replicate the no-start condition, clip to each plug wire and watch for flashing pattern as you crank the engine over.

[Risto1234]

Thank you for your reply! Will check both spark and fuel pressure next time it occurs