Starting issues Mercruiser 2008 4.3L

[KayakStripers]

Hello,

I have a 2008 4.3L Mercruiser in a Maxum 1800. The past 3-4 years we have been having trouble with either the boat having a lot of difficulty starting up, and then occasionally, dying when slowing to idle. Both instances it takes about 45-60 seconds of cranking before the engine will turn over. Sometimes I am about to give up and then try it one last time and it will start up and run fine for the rest of the day.

I'm wondering if anyone is familiar with this engine? Where is the best place to start? My intuition is thinking to start with these:

• Battery: check if there is enough CCA (though it's a 2014)
• Carbuerator: needs to be cleaned? I don't believe it has been cleaned, we just winterize it each year.
• Gas: We don't add stabilizer except over the winter, and it is usually ethanol 10%. I just bought 32oz of sta-bil marine. It is harder to start with older gas, but we have problems after recent fill-up's too.

Anyone have any tips?

Thanks in advance.
Ian

[TFKiv]

Yeah, they're pretty notorious for leaky/dirty carbs doing this. Also more of a long shot, but maybe worth a check...the main line electrical cannon plug connector that sits on top of the engine behind the carb can get corroded on the inside. when the engine bay is cold the rubber outer shell of the connector can shrink just enough to let current through(connection made) and after it gets warmed up it can expand just enough to stop the current (break connection) so you get no juice to the starter solenoid. Clean the connection... a little dielectric grease...

[KayakStripers]

Thanks. I will take a look at the cannon plug too.

Based on the symptoms it seems likely there could be a plugged pilot jet so it is having trouble to pull in gas when starting or idling. I might try sitting some seafoam in the float chamber and seeing if it will clean out the jets a little. Worse case I might send the carb out at the end of the season for a rebuild.

[Roccus]

This sounds purely like a fuel issue.... more specifically... a flooding issue... does the engine start good cold ?.... most likely a good carb cleaning is in order... Today's fuel has specific problems associated with it... when was the last time you changed the fuel filter? do you have a water separating fuel filter... you should.... clean the carb and check the float level... the addition of a new needle and seat would also be a good idea... Star tron is the best fuel additive out there... run it year round to help avoid fuel related problems.

[KayakStripers]

Hey Roccus. More recently the issues have been when starting cold. Then every 5-8 trips it sometimes stops when slowing to idle while running hot. If I have to replace any gaskets, needle, etc. I will probably just send out for rebuild at the end of the season.

I don't believe the fuel filter has been replaced. We have taken it to a marina for winterizing and maintenance, so I will check the log.

[TFKiv]

Yeah the wire was more of a hot issue. Does sound more carb related. Do you play with the throttle in neutral when having trouble starting it?

[Kappy]

Also make sure the tank vent is open and not allowing the fuel pump to create a negative vaccum in the tank. That will cause fuel starvation.