Mercury 2000 30 HP stopped working

Hi, I have a 2000 30HP Mercury 2 stroke which has rarely been used and probably never serviced before I changed the gear oil, put in new spark plugs and renewed the petrol in the last few weeks. It was misfiring at high speed before I put in new spark plugs, but then ran beautifully. After a good run I put muffs on to rinse it out, and pulled it over to start (forgetting to pump the fuel from the tank I think), and heard a backfire or loud pop. I haven't been able to start it since and there is dark oil and fuel coming out of the vents the muffs go over, every time I pull it over. Any ideas what the issue may be?

Fouled plugs.

Jeff

fastjeff said:

Fouled plugs.

Jeff

Click to expand...

Thanks Jeff. Is it best to clean them with WD40 or carb cleaner?
If this keeps happening, what may be the cause of it?

I think that carb cleaner + rag is good. Plugs can become fouled if ignition is weak, or too rich fuel/oil mixture. Four stroke engines it can happen if piston rings are not good condition. Also prolonged low speed operation can cause plugs to become fouled. If choke is not working right, also one reason to fouled plugs. Maybe engine operation temperature is too low.

A shot of starting fluid often helps as well.

Jeff

Thanks for your help - I'll give it a go.

Just an update to this - I cleaned the spark plugs with carb cleaner and after a lot of hard pulling without the choke on, got it going. I'm a little bit weary of this happening at sea, but will buy some spare plugs and flares to be safe

If it was not properly stored and fuel was left in the carbs , They need to be cleaned as you could be flooding out.