Mercury outboard running rough - Cleaning the carbs - Troubleshooting Part 1

Step 1 of getting my outboard motor running properly again. Troubleshooting and figuring out where the issues are.

[@dancousin2195]

I just cleaned my carbs on a 2000 Merc 90 ELPTO. Thanks for the video. I've run E10 87 octane gas since 2010 when I bought it and much to my surprise it was clean. I am careful to use a high volume gas station so I know the gas is fresh when I fill up. I do run through the fuel before 1 year. I help it with using the fuel in my lawn mower. I do run a fuel/water separator between the tank and the on motor fuel filter. I don't run the bowels dry either. I do run marine stabil and 1oz/gal seafoam. She was running a little rough but now its easy to prime and start and idles just fine. Thanks for the video.

[@Barbaralynnmusic]

I let some diesel soak in the spark plug holes to clean up the gunk in my 2 stroke 50 HP Merc. Spin the prop a few turns by hand every couple of hours. Let sit overnight then turn the ignition to blow the diesel out the holes. Bought a cheap camera to see how clean it got. 2 treatments and running a gal of gas with a can of sea foam in it made a world of difference. Bad compression will make it also seem like a carb problem. I just saved myself a ton of money by doing the lower unit myself. Replaced the impeller and the entire bearing carrier assembly. I'll post some videos soon but I have done some major repairs thanks to Dangar Marine videos and the rest the youtube family. Thanks for your video.

[@jdanielbiz]

You would be surprised how a small amount of water can effect operation. In most of the US there are fuel suppliers that sell Non-Ethanol gas. Use the non-ethanol gas along with a high quality fuel treatment, and install a water separator on your motor between the tank and the fuel primer bulb on an outboard. This will save your carbs, and your summer!

[@heathmayne1540]

Thanks for the video you gave me encouragement to have a go

[@hrmthermalimage]

Great Video, I just did my 1996 60 hp merc 3 carbs, just cleaned them up good there was minor dirt but enough to clog the top carb main jets, the motor was sputtering in from 2000 to 4000 rpm. but now its as it was 20 years ago LOL, Thank you for the great videos....

[@bucksgarage1]

Glad you had success.

[@sagitario12ish]

Nice video buck, but you already made the part 2? Thanks i learn much with the comments too.

[@aNuthaRedneck]

Just a note from my experience. Alcohol gas is hygroscopic. If left in tank for much time it will accumulate water from the moisture in the atmosphere. It's like it runs great first of summer but by end of the summer it runs like crap. I often have to siphon water out of the corner of my tanks with tank elevated so it all runs to lower corner so I can reach it with a tube that I have connected to a primer bulb. Another work around is to use sta bil or any good fuel stabilizer to treat fuel for moisture. Caution.. I have also had issues where sea foam or other fuel treatments eat up the rubber parts in fuel systems. One other thing. I have had a couple of mercury outboards that had little or no power but ran like new after I replaced the switch box. Some of you have posted issues which could be air leaks in the fuel line. This often results in acting like it runs out of gas or is not getting enough fuel.

[@SoulFood4You]

Do you know what size are the tubes that attached to the carburetor? and what size is the tube that the fuel filter is on? Thanks

[@kennethshook2564]

Looks like you could do a test by draining the bowls first to check for water .

[@coreymaynard6153]

Hopefully you still look at new comments, great video! I have the same set up, 04 merc 2 stroke 50 hp. How ever at idle it would back fire or cough every few seconds. Fuel lines and water separator from tank to motor is new. I removed the carbs and took them apart and didn't really see any blockages but I blew it all out anyway. Do you know a link or where I can order the gasket sets for these. Had 2 of them rip up in the corners. Also new fittings for the hose that links them all together. Mine are terribly rusted. Hope this fixes my problem.

[@giloquendo]

Questions that screw that goes on the bowl jet is it sealed or does it has a hole

[@kiven7722]

helpful video. thanks.

[@stevetapsell6819]

Very good video I have a mercury 50hp 1999 4 stroke I found your video really well done and easy to understand Thanks so much

[@louisblea993]

Did you put new gaskets in the carbs when you put them back together? If so what part number did you use. struggling with finding the correct kits for my 05 WME carbs. Thanks.

[@bucksgarage1]

I didnt, the gaskets were in ok shape.

[@brianlove400]

Hi Brett: I watched your wonderful videos and dove in to rebuilding my 3 carbs on my 2003 90hp Mercury. Rebuilding was easy. Now I cannot figure out how to get the bolts back in the bottom carb set. The top 2 carbs set on stationary bolts sticking out of the motor. the bottom carb is held on by removable bolts that wont clear the bottom cowling without going in at some ridiculous angle all while trying balance the front baffle system and a gasket on each side of the carb. Any experience or advice with this ???

[@bucksgarage1]

Brian Love I dont have any advice right off. Is the cowl removable? I was working on a Johnson outboard ober the weekend and the cowl was removable, it was really convenient and only took a few mins to get off.

[@iveneverdonethisbefore8390]

You have to put the bolts through the carb before you set the carb in place. It's tight but you'll get it. If you put the carb in first, then try to put the bolts through, there is no way because of the cowl as you say.

[@nicholasphillips3342]

@@iveneverdonethisbefore8390 Just pulled mine off and was wondering about this same thing. Random luck i found this, thank you

[@iveneverdonethisbefore8390]

Good luck!

[@Artoconnell]

@@iveneverdonethisbefore8390 one 10mm or 3-8 hex and you can lower the skirt halfway down. :)

[@danpoli5149]

Hey where can I find the carb drain bolt, I have water in my fuel and would like to drain the carb without taking it out, have the same motor in 90hp thanks

[@bucksgarage1]

At 1037 in this video you can see the screw.

[@FastenDeezNutz]

I run my engines dry before long term storage. And they always start up again after fresh fuel is added.

[@bucksgarage1]

I do the same thing now.

[@MrLike2surf]

I do that too. But, I found that running them dry is not good enough. There is fuel still left in the carb bowels. That fuel gets old and can absorb moisture. So they are not actually dry.

[@reid092353]

Jim Barnhart Take it a step further & keep choking it. That helps to alleviate more fuel out of the bowls.

[@bucksgarage1]

@@reid092353 never thought about that.

[@timjohnun4297]

I know this is a bit old, but probably a good time to put it out there - running the carbs dry is fine for winter storage, but one thing I have realised, after working on one of these engines recently - when you go to start it up for the first time after winter, when you first pump the fuel into the bowls, use premix fuel. With an oil injected 2 stroke, when you fill the bowls with the primer bulb, you are filling the bowls with straight fuel. No oil is added. Given that the outboard can run for a few minutes on just the fuel in the bowls, it's probably a good insurance policy to do this.

[@gilfredooquendo9969]

Hi I'm new at this whats the name of that rod that controls the throttle on all 3 carbs mine is broken and I need a replacement thank you for a well explained video

[@bucksgarage1]

Carb linkage / throttle linkage.

[@jesseschmucker52]

Will start rebuilding mine tomorrow on a mariner 115

[@williamriley2528]

Looks like you need a 10 micron water separator/filter on the back of that pontoon...

[@bucksgarage1]

That's exactly what I did in the next video.

[@FastenDeezNutz]

@Buck's Garage, what state are you in?

[@bucksgarage1]

Ohio

[@snookslayer4559]

I took my Mercury carbs out today for the first time ever, for same reason... sputtering boat won't plane. My carbs look identical to those. I sprayed em down with carb cleaner, reassembled and .... no improvement. Even changed the fuel filter and spark plugs. So I've taken the carbs back out for more thorough cleaning / long soak. I'll try that flashlight trick. Can the jets be unscrewed for better cleaning? Running out of options.

[@bucksgarage1]

Yes they should be able to unscrew. It took me a long time to get mine running correctly but since then it has been really reliable.

[@snookslayer4559]

@@bucksgarage1 I think I found my problem.... the 3rd carburetor (bottom) is missing the pointy jet coming out of the brass tube between the float. Can't understand how it ever ran correctly, but it's obviously not right. Had to check back to this video to make sure it's supposed to be there.. and it's there on all three of your carbs. So how to replace that missing jet, or can I? I can't find a video showing anyone removing that part. Take pliers and twist the brass tube? Doesn't look like there's anywhere to unscrew.?.

[@noneshere]

Sometimes ...you use a small torch and an EZ out tool. The heat loosens them up then the ez out carefully spins them out . You put another barrel in while hot and the carb metal shrink grips the tube solid again.

[@thestruggler3338]

I found a blockage of old fuel line at the elbow coming right out of the tank. Shot out like a cannon when put on the garden hose.

[@kenh6521]

Buck, My motor will not start. 25hp merc, tiller, 1991. I cleaned the carburetor, it was perfectly clean inside (no issues at all) but I blew all the jets out anyway with carb cleaner. I have good spark at each of my (2) plugs. Compression is 120psi at #1 plug & 122 at #2 plug. After cleaning plugs & attempting to start. Each plug had fuel on the tip of electrode (so I assume I have good fuel supply) gas on tip of plug means fuel was there, right?. Float valve moves up & down freely during carburetor cleaning process. Internal Baffles/gaskets in carburetor all in good shape. I did not replace anything, I cleaned & reassembled the unit. From the beginning of my troubles, Initially the motor would crank and idle just fine but not run full throttle without asolating between full throttle & bogging down. revving up & bogging down, back & forth, every few seconds, so I pulled & cleaned the carburetor. Now motor will not fire at all (will not crank up) (fyi: pull string start). It don't even sound like it wants to start. I've checked my fuel line primer bubble (it gets hard after a few squeezes) normal I believe, right?. External fuel filter screen is clean. Fuel lines looks good (no cracks/damage). I have fuel/spark/air. The motor should run! I'm at a loss here. Any suggestions? Checked electronic module (its solid state) what can I say, its clean, wires not crimped, no burnt wires, looks new or very good to me. Finely: I'm new here, how do I see / find your reply in a day or 2 when you do reply? [e-mail]. Thanks, Ken in Monroe, NC

[@bucksgarage1]

Ken have you checked to see if your fuel pump is actually pumping fuel? If it were me I would give it a squirt of starting fluid and see if it tries to crank up. ( I wouldn't do that often because it removes the oil coating from the cylinders) if it starts up even for a little it's a fuel issue. If not I would beleive that you have a ignition issue. I have seen spark plugs spark outside of a cylinder and once under compression not spark.

[@kenh6521]

@@bucksgarage1 Buck, 1st off, thanks for your response & your time. I did not know there was a fuel pump on this motor. I thought the baffles inside the carburetor acted as a fuel pump. Where is the fuel pump located on motor (I'll check utube for help here) while I wait on your reply. In the mean time, I'm buying: - 2 new plugs. - starter fluid (per your advice). - 1 gal can (NAPA) carburetor cleaner. (Soak carburetor in bath for 2 hours, disassembled to clean all possible ports I may have missed).

[@bucksgarage1]

@@kenh6521 mine is on the right side of the engine. Check out this video and see all the crap that came out of mine when I was having issues. kzbin.info/www/bejne/imeXnaWLhq6KZ8U

[@kenh6521]

@@bucksgarage1 Buck, that was a mess, man I'm glad you found that. No fuel pump on my small 25 hp mercury. Fuel goes from the inlet valve to the external screen/bowl, them straight to the carburetor.

[@label1877]

Was your issue coils?

[@turdsandwicher]

How similar is this to a 90hp 4 cycle Merc outboard? Does it have the same carbs? Mine is stored at a marina and they want to charge $500 to clean the carbs. I might try it myself. What the heck I paid them to winterize and store it.

[@bucksgarage1]

4 stroke will be a little different I'm sure. The concept should be very similar though. Just take a video of it coming apart and you will have a blueprint for re assembly

[@drakeastro8131]

Owned my outboard for 13 years and In the last year or so i have started to disconnect run the carbs dry as you did. Recently the motor has been bogging out on me and have done a carb clean which fixed it. Coincidence? Not running mine dry anymore

[@bucksgarage1]

I guess it depends on the gas you use. Are you running Ethanol free gas? If so I wouldn't worry about disconnecting the fuel line either. When I was a teen I never worried about anything and my 85 evinrude seemed to start every time. Since the intro of Ethanol I have had problems if I dont take cautions.

[@drakeastro8131]

@@bucksgarage1i dont use ethanol. Too scared of all those horror stories so i stick to regular. Funny thing is that after all these years i was expecting it to be full of crud but it looked really good except for what ever it was clogged in it.

[@daver1824]

Did you have any trouble with it revving up outside of the water?

[@bucksgarage1]

Not that I recall

[@joerudy5180]

I have a 97 merc 175. Looks like the same carb. I have Gas pouring out of the top carb. Could a stuck float be the issue. Or would it be a Reed issue

[@bucksgarage1]

In sure it's a stuck needle valve on the float

[@dirtychina5964]

Do you you use the gin for lube?

[@mg82949]

Sure doesn't help anyone thinking of doing it themself..guess I'll stick with seafoam and hope it keeps running.

[@evanheffley1625]

The jet in the bowl is the main jet.

[@gilfredooquendo9969]

I'm new at this does an 80 hp also has 3 carburetors?

[@bucksgarage1]

It should be similar

[@terrywilson1813]

I have a mercury 90 and it seems to me that mercurys are notorious for having fuel problems

[@bucksgarage1]

I agree. If I have a choice I would take a evinrude over a Merc but I have had real good luck with this one since I went through it.

[@sofaninsafansah5142]

I have mercury 25hp year 2005. And i am looking for fuellpump,can you help me, I from indonesia

[@Artoconnell]

Hey Sir, You would be shocked at how much debris is inside those passages. a carb wire set is a MUST.

[@bucksgarage1]

I actually picked one up last year for another carb I was having trouble with.

[@thestruggler3338]

bit of carbie cleaner u rekon?

[@glenvarza2111]

Do u not haveca water separator!?!?!

[@bucksgarage1]

I do now.

[@tonymartinez4075]

Having backfiring issues with my 2001 90 Mercury

[@Lacrosseprodigy]

Tony Martinez same on on my 1996. It misfires in idle but runs perfectly after i begin to accelerate just past idle. Have you been able to fix this?

[@gangsterbob2028]

You need to run more lean. To much air causes back fire.

[@noneshere]

Yup, popping is too much air. (Lean)

[@mikeeverman1420]

Thanks for the info people tall me that they are hard to rebuild that just anybody could do it

[@paisa007]

Was your fuel tank ventilated?

[@bucksgarage1]

paisa007 yes its vented at the fuel fill

[@559jbam]

Brett Buckley what do u mean ventilate I am running a small tank instead of built in due to junk in main fuel tank

[@bucksgarage1]

559jbam the small tank should have a vent on the fuel cap. It has to be open so the tank does not vacuum lock when it is pulling fuel out. I have a motor quit and bk ot want to run because of the vent being closed.

[@559jbam]

Brett Buckley oh ok thanks

[@glenvarza2111]

Who takes carbs apart and doesn't buy rebuild kit lmfao

[@bucksgarage1]

Who buys a rebuild kit when it's not needed?

[@topanoreal]

Hi,imam Indonesian Can you help me,iam looking for ring piston mercury 40hp 3 carburator

[@bucksgarage1]

Try calling for emailing wholesale marine. I get all my parts from them. www.wholesalemarine.com/mercury-outboard-piston-kits/

[@topanoreal]

@@bucksgarage1 Thank you guys

[@oldawg8643]

bad gas

[@wilsontrevor506]

I can't get full power out my mercury 55

[@workinprogress6726]

Try pumping your primwr bulb when at full throttle. If it gets up and goes then its your fuel pump. Its weak. Mine dis the same thing. If not then clean or replace fuel lines. You can buy fuel line any size at autozone by the foot for like a dollar somthing. And rebuild carbs.

[@kylewoodward7078]

I have a 89 45hp classic 50 mercury. Do you know how hard these carbs are to work on. It runs GREAT until I hit full throttle, then it wants to miss. I just did the plugs and a seafoam treatment, but haven't taken it out yet. I can't get it to miss when I'm running it in a bucket, just when it's under a load at full throttle.

[@workinprogress6726]

@@kylewoodward7078 stator is bad. Carbs are easy to clean.

[@user-jz7sp5tt1g]

I, wantcrank, worke, ple

[@bobberger918]

Sta bil

[@chevytahoe9430]

The majority of this video was took up by saying uh and um and repeating yourself 😂

[@bucksgarage1]

It is very easy to point out flaws in a video when you don't make them yourself. I made this video a long time ago when I was just getting started at this and new very little about how to make a consumables video. Please take a min and watch one of my newer videos. I have come a long way with editing and knowing what to say when.

[@chevytahoe9430]

@@bucksgarage1 all I heard was uh,um and the huge pause between you repeating the same thing over just slower… otherwise the info sorta helped so I may try it or just have the marina do it but it’s $500

[@adrienbastarache8096]

you skip the part of taking the carburetor apart,you do this for a living,thumbs down.

[@bucksgarage1]

I don't do this for a living. It is just a hobby. When you say I skipped taking it apart do you mean off of the motor? The whole video was disassembling the carb. I am aware some of my older videos are not the best. I have been trying to improve on newer videos.