I idled around a small lake all day yesterday while fishing. When I was ready to leave, I cranked my motor and it starting idling in basically full throttle. It was VERY loud and started burning oil/gas VERY quickly. Hard to explain, but what would cause the motor to idle/rev VERY HIGH as soon as I turn the key? All help is GREATLY appreciated!

stuck direct injector, hole in tracker valve diaphram

Im curious to what you found out. my 2002 optimax started this today. I had to drift back down river cause i was scared it was gonna blow the motor. I cranked it 3-4 times and it would rev to wot. Took it to a mechanic and we checked linkage and fuel and all. The mechanic i took it to didnt have a diagnostic computer to hook it up. (yamaha not merc dealer). we've kinda narrowed it down to about ten different things ha. My ignition switch has been giving problems like it was beeping the other day before i ever cranked the motor. It has like a choke built into switch. I know its dfi and shouldnt have choke but could it be hung in a choke like mode. It is blowing smoke when you crank it for the split second i can crank it for without blowing the motor. its not missing or anything just idling way too high.

Like Martin suggested a leaking fuel injector or a rip in the diaphram in the tracker valve I saw more tracker valves cause this problem. What happens is fuel will seep over into air side of the rail It wil scare the hell out of ya when it happens....OPTI

OPTI--Glad to see you back on here...

un metered air getting into intake? The tracker diaphrams that I've seen when compromised caused a air/fuel im balance and the motor would stumble not over rev. Merc. does not sell fuel rail diaprams alone, they sell the complete rail and it's costly. If you find that you need rails I have a vendor who can replace them and save significant money. We have used the replacement diaprams two times and the customers have had no further problems. Gary 512 250 9000

Not unmetered air into intake. Fuel seeping into air side of fuel rail and yes it will overrev. and it will cause a running problem and can foul spark plugs also Even while running with a small pin hole at 90psi fuel pressure and 80 psi air pressure fuel will enter the air side, Fuel and air imbalance would be caused by a week or missing spring yes I have seen them run with no tracker valve spring.When did Mercury stop saling just the diaghrams......OPTI