b85 Mariner 40 EL dies in idle after long trip

"hi again,

my 85 mariner 40

"hi again,

my 85 mariner 40 EL works fine until i go for a longer trip, about 20min with 2/3 trottle. if i slow down its all fine until i get as slow that i only use the idle speed of the engine to maneuver towards the pier. and that is the point where she dies suddenly. i then cant even start her except pulling the idle leaver up a little. if i then have her going again its fine for a while. then she dies again. in general do i not have any start problems. 99% of the time i turn the key once and choke her for a second or two and pull the idle leaver a little bit. the worm engine starts just by turning the key once straight away. it seems to be a problem only after a longer run at higher speed. any suggestions ?

Jan"

"It sounds like you may be exp

"It sounds like you may be experincing an igniton problem that shows itself when the components heat up. This is not unheard of.

When warm your spark may be getting weak due to bad stator, coils etc.

You need to do a bit of work here and troubleshoot the ignition system when the failure occurs.

You could start by simply checking your spark when the engine is cold and then again when it dies on you.

That would at least narrow it down to an ignition component if you find a problem..."

"Graham, I'm going the oth

"Graham, I'm going the other way, it might be running a bit lean. It could also be heating up and leaning out. First check the temperature after you long run, just put your hand in the pee stream to see how hot it is. If the engine has checked out electrically with Grahams test, richen the idle mixture screws 1/8 turn ccw and maybe bump the idle up. If that doesn't help you can just set it back."

"Hope we didn't confuse hi

"Hope we didn't confuse him - both are viable "

"graham, i will do that check,

"graham, i will do that check, but it does definitely not sound like running on one rather than two cylinders.

jb, the 'pee' is worm but not hot. the sea here is pretty cool anyway. 15 degree celsius south coast of ireland. i dont have a manual and dont exactly know which the idle mixture screw is, can you explain ? if i bump up idle speed i have very high revolutions in normal working conditions. i guess the gearbox does not like that in the long run and i find it too fast for manoeuvring the boat nicely.

Jan"

"you don't have to adjust

"you don't have to adjust idle speed if you don't need to. If the idle is high right now, then that could be an indication of a lean engine, either not adjusted correctly or a possible problem. each carb has a idle mixture screw, screwing them in leans that cyl or cyls, screwing them out richens the idle mixture. location of the screw changes with each different engine. from another site





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How to adjust carbs...101
06/12/06 at 22:40:58 Check your manual for the proper initial setting.

Most times its between 3/4-1.5 turns.

IF engine is running lean.

With the engine IN water and IN gear.
Turn the set screw counter clockwise until the engine starts to load up and slow down.
Once it loads up, start to turn it back clockwise until the engine starts to clean up and runs faster.

IF engine is running rich.

With engine IN water and IN gear.
Turn the set crew clockwise until the engine starts to stumble/pop and slow down.
Once this happens, start to turn it back counterclockwise until the engine starts to clean up and runs faster. <---TIP.....once you find this position, open the jet 1/8 of a turn futher and try it. If it stumbles on take off, return it to 1/8 of a turn back."

hmmm.....went out again today.

hmmm.....went out again today. the problem did not occur. i will come back here as soon as i have more information about my problem and how i progress in solving it.

thanks graham and jb for your help.

Jan