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sstout

Rebuilding Mercury carbs

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I was looking under the cowl the other day and I noticed my carbs leaking some gas. The motor is a 1984 mercury 60hp 3 cylinder two stroke. It runs really well. I've never had any issues. 

 

I bought this boat 3 or 4 years ago. Ive never had the carbs apart because it does run so well. I just bought a new gasket kit for both carbs and plan on pulling them this weekend. My thought is to pull them apart, clean them, and put all new gaskets in. Hopefully that stops the dripping.

 

The gas just drips every once in a while from the screw with a spring from under the carb. Maybe the float is stuck or needle is stuck? It happens even when the motor is off and has pressure from the fuel tank. Any ideas? You can see the drip in the pic. Like I said, the motor runs really well. The dripping gas just bugs me

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Thank you. That was one of my thoughts. I didnt buy an entire rebuild kit because of price and availability. I'm hoping it's just gunked up. Hopefully a good cleaning and new gaskets will do it. And new fuel filter. 

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3 minutes ago, sstout said:

Thank you. That was one of my thoughts. I didnt buy an entire rebuild kit because of price and availability. I'm hoping it's just gunked up. Hopefully a good cleaning and new gaskets will do it. And new fuel filter. 

YEP I HAVE CLEANED MANY NO KIT NEEDED

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Posted (edited)

I have an 86 Merc . 

 

I had a lot of carb issues with it . 

 

I put ethanol gas before  we knew we should not use it . 

 

It disintegrated the hoses and tiny pieces got in the jets . Gas was dripping from the bottom of the carb . 

 

I had it rebuilt by Bruce and it ran great . 

 

It happened about 5 more times after that as I think particles were in the lines . I had the carb off that many times to clean it out . I would spray WD 40 into the carb and dump it out on a paper towel and find small sand grain size pieces of plastic . 

 

I finally put a small fuel filter just ahead of the carb and one see thru on the tank fuel line . 

 

Problem solved . 

 

 

Edited by HB2

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Also the fuel pump diaphragm can disintegrate causing the same problems . 

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Good to know. I have always run non ethanol gas in it the four years I've owned it, but who knows about the guy before me. I'll take a peek at the fuel pump while I have the rest apart too. Maybe I'll see where I can fit another small fuel filter right before the carbs. I like that idea. I dont really want to be pulling these carbs often. I'd rather swap a filter out than pull the carbs back off to clean them

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I feel once the hoses have been compromised by ethanol , they will continue to break down . 

 

So I would replace all hoses from tank to carb . 

 

It's an 84 so it might be time anyway . 

 

 

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Take a real good look at the tips of the fuel inlet needles and if they show grooving they should be replaced. This may also be causing your leak. Good luck to ya !

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Thanks everyone. I'm definitely a fan of doing things right the first time. The more I think about it, the more I agree it's probably a good idea to replace all the fuel lines from the tank to the carbs. I'm pretty sure they are all original. I dont believe this motor has ever had much work done to it other than a few electrical things. It's super clean and runs great, so worth putting the effort in. I'll check the fuel inlet needle when its apart too. For all I know this might be the first time these carbs have ever been apart. 

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I have a similar issue with my 1985 75hp Mercury, I have gone through both carbs and ready to reassembly, but have no idea what the float level should be?  In process of getting a manual, but was hoping someone here has one or knows the correct float level.

The motor serial is A115675 with 14 series carbs.  

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HPort, I have a seloc manual. It's ok, not the most detailed in certain areas but it gets the job done. Theres three different types of carbs that these motors came with, so I think it depends on what style carb it is. Sorry I cant be more helpful. This will be my first time cleaning these as well. I will be pulling the carbs this afternoon and dissembling them tomorrow. 

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Here are a few photos of the carbs on our 1985 Merc 75hp, If you are cleaning carbs for a problem, I highly recommend pulling them and going through them as there are ports and dirt you cannot get to otherwise.  

The problem we are having that promoted pulling them was poor idle, hard starting warm and wet lower carb. It ran fine at 1/4 to WOT, but would die out intermittently at warm idle and in general poor idle.  We went down the path of lowest hanging fruit last year, rebuilt the fuel pump, cleaned the carb idle ports, replaced plugs and idle speed adjust and checked timing which made it better but still not right.  The plugs we pulled out were all even in fouling and wear, so ignition doesn't seem to be at the top of the list, although it is usually suspect.  Photographed each step on the teardown last week to see if there was a smoking gun, the lower carb float was closer to 1/2" height and the upper carb was 11/16" height which put it dead even with the top of the Venturi.  This is where I'm at right now, finding the correct float height.   sstout, what options does the manual give you for carbs?   Since the ground is covered in snow here I was hoping to get the carbs back on this weekend and see how it runs.  The last photo is the QuickSilver part numbers for the gasket kit, needle and seat with copper washer and the fuel pump diaphram kit for our motor.  If you cannot find parts at you local parts shop first, MarineEngine.com is a good resource.   Also included a photo from last week showing a couple of the Lakers we pulled from the South End of Keuka last weekend, had a good trip, we trolled early and put it two off the copper and spoons ( green) down 30', then when we starting having the idle issues we switched to jigging and limited out for a nice morning.

John

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Looks actually like the same carbs that are on my 60hp. The gasket part numbers were the same as what I ordered. Here's a pic of what the manual says about float level adjustment and an overall diagram. Hope this helps. I will be tearing into the same carbs in a few hours. 

 

 

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sstout,

Thank You !!!   

The carb rebuild is a straight forward job, just two caution areas. 

  1. Removing the linkage from the enrichment solenoid to the enrichment valve on the carb. Just carefully slide the linkage to disengage and use a small screwdriver to pop the linkage off the enrichment valve.  My fear was breaking the linkage as it didn't want to come off easily at first.
  2. Removing the float from the carb body, make sure you tap out the pins ( #9 in the manual) in the direction of the splined end of the pin, one end has splines to hold it in the body, the other end of the pin is smooth.  Same for the pin for the float lever. 
  • For easy of removal, I cut the fuel hose supply wire tie at the pump and pulled both carbs at the same time.  

Good luck with you rebuild and let me know if you have any questions, 

John

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Thank you. They came out pretty easy actually. Interestingly enough, if the numbers on the fuel lines are the date, this has the original hoses on it. They looked fine enough, but I will be replacing all of them with new hoses just to be safe

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Good to hear its going well, same here with original hoses. They looked good on the inside and not dry rotted, but replaced as precaution. 

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All clean and re-assembled. The plastic coupler for the throttle shaft that links the two carbs together will be here monday. Carbs will go back in tuesday and will be tuned. Should be back at it by the weekend. I've never tuned these carbs so that should be interesting...

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Posted (edited)

Nice that you found a coupler, carbs look good!

Just an FYI,

Did you look at the trigger and stator wires going to the switch box when you pulled the fuel line off the pump?  Two of the wires on our motor were rotted out and the insulation was  coming off. This wasn't noticed until pushing the new fuel line to the pump. Did a search and this seems to be a common issue with the Mercs.

 

Edited by HPORT
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Yeah. Looked everything over and looks good. How easy were your carbs to tune? I have the fuel mix screws set at the starting point stated in the manual. Did it take you long to get them into the proper mix?

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No, the 1 1/8 turns out was dead on for our motor. The carbs never ran better, idled perfectly and ran great until the ignition started acting up and eventually quit...there's another chapter coming up later this week on trigger and stator replacement if anyone is interested.

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Sounds good. Mine are set at one turn out right now, so that sounds like a good starting point and should probably be pretty close. Goodluck with the stater. Hopefully it's not too bad to do

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Posted (edited)

No spark at times and found broken and severally corroded wires coming out of the trigger and stator harness.  I never had an issue until pushing the fuel line past the wire harness.  Did not test resistance as it was obvious once I started to check the primary ignition. I'm replacing both since I'm there and they are both problematic areas given the age.

Edited by HPORT

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