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Message Subject: mercury carb issue???

bfunk73183

Posted 5/12/2009 10:04 PM (#377752)
Subject: mercury carb issue???

Posts: 315

here we go

my buddy has a 2003 mercury 4 stroke 90hp carb'd motor. and we seem to be having a few "issues" last fall problems started, hard starting, poor idle, and sometimes just killing. at WOT it would "hesitate" alittle, at 3/4 throttle it was like its "sweet spot" would run fine. got it winterized and the mech. said it might need some carb work done. yesterday we took it out for the 1st time and he added some carb cleaner to the gas. 1 can/6 gallons so he put in 2 cans for about 20 gallons (probably should have added more) got it started and went around the lake a bunch of times. carb cleaner seemed to be working slightly finally got it to 3/4 throttle and left it there. drove it for 25-30 min solid, idled back to the dock and turned off. went to restart didnt wanna start, got it running and with any throttle it would backfire and would barely run at all.

ive done lots of reading on this motor, lots saying the carbs in this motor are "picky" need very good quality gas add cleaners to every other tank, and that they clog easily. so possible carb cloggage? i also thought maybe plugs? fuel filter? primer ball? just trying to find some ideas. i was told maybe to shoot some carb cleaner right into the carb and run it? he doesnt wanna throw down $600 the dealer quoted him

thanks in advance for any assistance -ba-

curleytail

Posted 5/12/2009 10:55 PM (#377767 - in reply to #377752)
Subject: Re: mercury carb issue???

Posts: 2687

Location: Hayward, WI

I have a 1999 carbed 50 hp 4 stroke Merc. I had some issues with it this year right away too. Ran really rough at idle, ran better above 3,000 RPM. Started sort of okay, but overall didn't run great. Took the (4) carbs off and cleaned them out real well. The low speed jet was fairly clogged on the bottom two cylinders, and that seemed to be causing the problems. You could actually pull the plug wires off the two bottom cylinders and it didn't really change how the motor idled.

Cleaned everything out and it purrs like a kitten. Luckily, my uncle has always been handy with stuff and wasn't afraid of digging into the 4 carbs that are linked together. Looked like something I wouldn't have wanted to do, be he said it wasn't too bad.

Anyway, my motor pretty much ran like crap, and all it needed was a simple carb cleaning. I don't think just running carb cleaner through it would have been agressive enough to fix the problem.

curleytail

bfunk73183

Posted 5/12/2009 11:19 PM (#377774 - in reply to #377767)
Subject: Re: mercury carb issue???

Posts: 315

ya pulling the carbs off for cleaning makes me pretty nervous, saving my buddy the $600 that the dealer quoted him is a great favor but.........yeah

thanks for the insight

-ba-

Targa01

Posted 5/13/2009 7:48 AM (#377793 - in reply to #377752)
Subject: Re: mercury carb issue???

Posts: 742

Location: Grand Rapids MN

From what you said it sounds like you are running a little on the lean side because of the WOT and cold start issues. At WOT it may not be able to supply enough fuel to sustain smooth operation but it can supply enough at 3/4 throttle but I would guess it's still running lean even then. During "cold" starts more fuel is required then also hence the need for chokes. A partially plugged carb will affect this also. It would take time for the cleaners to do its job unless there is dirt/sand deposits the circuit then you would have to take it apart to find out.

I would guess the engine wouldn't restart after you ran it because it ran a bit hotter than normal from running under a lean condition. A hot engine can have the tendancy to start hard.

That's my guess.... sitting here.. from my desk... it's an opinion to say the least...

Good luck man!

JohnMD

Posted 5/13/2009 9:41 AM (#377814 - in reply to #377752)
Subject: RE: mercury carb issue???

Posts: 1769

Location: Algonquin, ILL

Bfunk: I have the same motor but mine is a 2000, I had the exact same issues, Trust me just pay the $600 and get it done right, after mine was done it ran like new just be sure to use the merc carb cleaner in every tank of gas and to use and run either stabil or sea foam before storing for the winter

bfunk73183

Posted 5/13/2009 9:59 PM (#378025 - in reply to #377814)
Subject: RE: mercury carb issue???

Posts: 315

thanks for the help yall

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