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2001 90hp mercury idle issues...help!

Posted By: whopper22

2001 90hp mercury idle issues...help! - 05/02/15 02:11 AM

Ok, i have searched on the forum but i havent had luck with an answer yet. Here is my issue...
My 90hp mercury ouboard is notorious for being a COLD COLD starting motor the first few trips of the year. I decided this year to fill it up with good gas, changed the bulb, changed the battery. The motor will start when choked at the key, then it will idle 3-7 seconds and die like its not getting gas. Its done this for years on the first trip but eventually coughs out and goes. I put a hose hookup on it today and tried to get through the headache before i hit the water. I tried for 45min. Starts, runs for a few seconds, possibly longer if revved in neutral, then dies. Im going to buy a new fuel filter tomorrow morning. Am i missing something? Any ideas? Any previous threads addressing this issue?
Thank yall for your time, i really enjoy reading all the stuff on here.
Posted By: Jeff_W

Re: 2001 90hp mercury idle issues...help! - 05/02/15 11:12 AM

Make sure your bulb stays primed
Posted By: opus

Re: 2001 90hp mercury idle issues...help! - 05/02/15 11:57 AM

Have carbs ever been cleaned?
Posted By: whopper22

Re: 2001 90hp mercury idle issues...help! - 05/02/15 12:55 PM

The bulb stays primed now that i changed it. Carbs havent been cleaned. Im hoping to avoid it, but it may be finally time for a complete 100% fuel system clean and service. Hoses, carbs, everything. Just looks like a chore haha. Thanks for the response guys. Any other suggestions before i roll up the sleeves and get to it?
Posted By: jbobo

Re: 2001 90hp mercury idle issues...help! - 05/03/15 01:38 PM

Go to Home Depot in the lawn mower department. Find a 4 oz. bottle of "Mechanic In A Bottle". Follow the instructions. I never rebuild carbs anymore. It is safe for all outboards, lawnmowers, weed eaters, any small engines. Works like a charm and isn't harmful to any plastics or rubber in the carbs. It will clean out any gummed up ports and your carb will look brand new and shiny inside.
Posted By: jbobo

Re: 2001 90hp mercury idle issues...help! - 05/03/15 01:47 PM

That may or may not fix your problem. My evinrude does the same thing most times. It just takes a few minutes for the motor to reach operating temperature and it idles fine. That is why most outboards are made to automatically fast idle when cold. Once they warm up they will idle down. There could be something wrong with the ignition so it won't go to the fast start mode. My engine usually coughs out once or twice, after choking it the first start on a trip. After that it fires up and idles up to warm up and then idles down and runs good.
Posted By: gary purdy

Re: 2001 90hp mercury idle issues...help! - 05/03/15 02:31 PM

They will also act like that if the idle air screws are adjusted to lean. A cold motor needs more fuel to idle. #15 http://www.boats.net/parts/search/Merc/Mercury/2001/1090411YD/CARBURETOR/parts.html
Posted By: whopper22

Re: 2001 90hp mercury idle issues...help! - 05/03/15 03:01 PM

Thank yall for the suggestions... Replacing the inline fuel filter tomorrow afternoon and then if that doesnt work ill try what ya'll say! Boats been sitting too long i guess. Lesson learned though! Just means i need to fish all year to avoid this problem haha.
Posted By: Topwater2

Re: 2001 90hp mercury idle issues...help! - 05/03/15 11:38 PM

Tune up will solve it all.
Posted By: whopper22

Re: 2001 90hp mercury idle issues...help! - 05/06/15 11:37 PM

Hey fellas, just wanted to let yall know that the mercury is finally running... Knock on wood. Thank yall for the help. I replaced the bulb, replaced the spark plugs. The real problem was definitely in the carbs. The floats were stickin. Sprayed some b-12 in them let em sit a bit sprayed em again and she started right up and started idling. It was idling rough, and only on 2 cylinders, so with some test light work and some minor adjustments to the idle mixers its firing like an old mercury again. Aint the smoothest, but its goin! After i get out and test it out ill keep adjusting till its smooth, but just wanted to thank yall!!
Thanks again!
Posted By: jbobo

Re: 2001 90hp mercury idle issues...help! - 05/10/15 03:15 AM

Be careful spraying b-12 in the carbs. If you start it with b-12 in the carbs, you are not getting any oil on the bearings and rings. It will wear out the bearings and guald the pistons in just a minute. That's why I suggested the Mechanic in a bottle. It will do the same thing but you will have your gas/oil mix for the bearings and pistons, and the MIB to eat out any gummed up parts in the carbs. I've done it several times and it always cleans the carbs out. Hope you don't have any issues with the b-12. Glad to hear it is running.
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