1985 Merc 50hp 4cyl Carburetor Rebuild

Hi All,

Im working on rebuilding my carbs this fall and I'm looking for some general advice. I got the carbs off, but it was quite tricky to gain access to the two bolts that secured the carbs to the powerhead, especially the bottom bolt on the starboard side. I took the starter motor off, but still had trouble accessing these bolts.

First question, is there a good tool to use to fasten these back on? My manual says 11Nm, but I definitely won't be able to get my torque wrench on these guys.

Second question is the parts I need...carbs say WMA3-1; WMA3-3 with a 12-84 (I assume thats the manufacture date?) Says my rebuild kit is quicksilver 1395-9023 and gasket kit is Sierra 18-7215. Should I go ahead and just order two rebuild kits, or take them apart first to see what I need?

Third, any notes on disassembly/re-assembly? First time doing this so I am a little hesitant.

When I took these off, I just unscrewed the fuel inlets and immediately noticed some junk built up on the screens, particularly on the lower card. I decided to rebuild after having problems with my hole shot this summer. Engine would start and idle fine, but seemed like a lack of fuel, boat (13' whaler) wouldn't get up on plane even at "wot." Quick fix was an entire can of Johnson power clean or whatever that magic juice is called.

I've replaced the internal fuel filter on here every year I've owned the motor and am using clean tanks and new EtOH friendly fuel lines. Thinking maybe these just need a good cleaning.

Any and all advice is greatly appreciated before I start taking these apart.

Thanks!

You don't need a torque wrench. Just tighten the nuts tight and go boating.

Jeff

What fastjeff said.
I have a '92 Merc 40hp 4cyl 2 stroke; took 2 WMA 71B carbs apart in '95; had an excellent Mercury shop manual containing many carb pictures - priceless; manual spec'd how to dis-assemble and tune the carbs; not complicated if you go slow and note\take pictures where each part goes; my float bowls had 3 parts - a fiber bowl gasket, an internal fiber washer on the nuts that hold the bowls to the carb, a half moon metal baffle, a plastic? float; some on the forum say you should soak the metal parts overnight in a carb cleaner and use compressed air to blow the internal passages; the Merc gasket kit and rebuild kit I bought for mine had all the parts I needed - about $75 per carb; there are many Youtube videos on carb cleaning. You could also search this forum for carb threads.

I recently took these part and they are spotless. Looks like someone had recently rebuilt them. Although, from what I can tell the parts are different from the quicksilver parts I ordered. I double checked my part #s and they are correct. When I took the integral fuel pumps apart they were missing a gasket after the diaphragm. The mere parts diagram online isn't great quality and the seloc manual I have has the same poor resolution photos. Was looking for advice on putting these back together, should I include all the gaskets that the diagram calls for or put back as I found it. I think the previous owner had put the diaphragm in backwards too, is there any good way of knowing which direction these gaskets face? I don't trust the teardown so thought I would ask here.

Thanks!

I put the black rubber on to contact the metal for a better seal.-------There is very little that can go wrong with these carburetors.-----What is your motor doing / not doing ?-----What other trouble shooting if any has been done ?

Where did you find a complete Carb kit for this 1985 Merc. 50 hp, which I assume was A WmA3 Walbro? $75 is a bit much, but I can't even find one! 2 question what does the the half moon metal float baffle do?

Sea Nymp said:

Where did you find a complete Carb kit for this 1985 Merc. 50 hp, which I assume was A WmA3 Walbro? $75 is a bit much, but I can't even find one! 2 question what does the the half moon metal float baffle do?

Click to expand...

I was told by a master tech that that baffle keeps the fuel from bouncing around.. so it stays in the bowl when your boat bounces in the waves. don't loose it... NLA part..

how did the rebuild go? I have the same outboard.. cannot get it to idle after replacing the controls.... and the trigger coil.. and the fuel lines..

gonna take em off again do the fuel pump this time and the needle valve.. have the same leaks around the bowl.. seems to always want to leak around the bowl...

rocknroj said:

I was told by a master tech that that baffle keeps the fuel from bouncing around.. so it stays in the bowl when your boat bounces in the waves. don't loose it... NLA part..

how did the rebuild go? I have the same outboard.. cannot get it to idle after replacing the controls.... and the trigger coil.. and the fuel lines..

gonna take em off again do the fuel pump this time and the needle valve.. have the same leaks around the bowl.. seems to always want to leak around the bowl...

Click to expand...

I ordered the kit mentioned in a previous post. I replaced all the gasket in the top carb only. It was the only one given me problems. I had a little trouble getting the rubber seal on top of the bowl to stay in place. Put the carb back on, gas poured out of the bowl. Took the carb off again. At some time someone had put some kind of glue in a couple of places in the grove where the rubber gasket goes and it wouldn't lay in the grove correctly. The glue was hard and I had to take a small drill bit being careful not to mess up the grove. Got the glue out, lightly sanded the grove all the way around with 1000 grit, and cleaned it with carb cleaner. After that I took off the float, and needle valve, set the float to specs, and sprayed the seat with carb cleaner. I bought some Permatex-Form a gasket #3. It comes in a can and gas doesn't effect it, it will not harden or become rubbery, it is not silicon, it is sticky and will hold the rubber bowl gasket in place. Use very little, I applied it with my finger. Put it on the side that lays in the grove, let it set for about 1 hour, and applied same way to the side of gasket that the bowl sets against, let it dry a little while also before putting on the bowl. I even placed a little on the very bottom around the bowl. Put the float & needle valve back on. Took the new gasket ring for the bolt that holds the bowl on and applied small amount of #3 on both sides of the gasket, did the same for the inside gasket, that sit on top of where the bolt screws into. Make sure they dry enough to stay in place before you put the bowl on. Try to line up the bowl so that you have the same amount of rubber gasket showing all around the bolt edge. Press the bowl down holding it in place for about a minute apply same amount pressure all the way around. Put the bolt back in the bowl making sure the gaskets don't move. Run the bolt up as tight as you can with fingers, then press on bowl again without moving gaskets, let it set for a little while, then turn bolt with took until it snug. I would let it set over night, then just snug the bolt up tight, don't over do it. Put the bowl on the next day. If everything is right you won't have any leaks. if you do it might be around the bolt, just tighten it a half turn at a time, until it stops. I had a small drip about every 30 seconds and 1 half turn stopped it, I had not leaks any where else, and motor is running great

Sorry I made a couple of typo in the message- Line that reads-turn the bolt with took- should be- tool
Line that reads Put the bowl on the next day- should be- Put carb on the next day