1975 Mercury 850 Help with Carb/Fuel Issue

[Island_oki2000]

All,

I just finished rebuilding my carbs and reinstalled on the motor. When I primed the bulb to fill it with fuel I noticed the botom carb was squirting fuel out the top of the bowl where the Jet, Bowl Vent. I read a little about this and could it be a stuck float or the needle not seating correctly?

There where a few parts still in the rebuild kit, but no idea where they could go. There was one very small brass ring ( I think goes in with the needle and seat but could not get the other one out, and did not want to force it) and a very very small brass piece that I don't know where it goes, the carb diagrams I have are very blurry and don't help.

Help please.

Thanks,

 

[Laddies]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

It's one of 3 things, needle and seat, bad or stuck float or the float level is to high. As far as te washer there are a couple million in trash cans and the old washers aren't leaking.

 

[Island_oki2000]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

Well then, it's one of two things then, bad or stuck float or the needle and seat, because for my carb there is no float adjustment. It runs on a single small rod in the center of the bowl from bottom to about midway up and had no other adjustment.

When I put the new needle and seat in I turned the bowl top upside down and it stopped me from blowing air through the fule line, so I'm thinking the floats, can I put it in a cup of water or fule and see if it float to check it or is there another way?

Thanks

 

[Laddies]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

The float levers are adjustable and just hook the fuel line from the tank to the carb and pump the bulb with the carb on the bench or in hand.

 

[Island_oki2000]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

You are talking about the two metal pieces that work together to seat the needle, I did notice the old ones were bent a little. I'll have to check that. Hopefully it is something that simple, I hate that I have to take this thing apart again to get them off but hey, it will be good practice.

 

[Island_oki2000]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

Was able to get the bowl covers off without removing the entire carb. Bent the metal lever to adjust for the float. Bottom carb is good, does not leak. Thought top was good but as I was priming the bulb I noticed a lot of fuel coming out the carb throat.

Could this still be the needle and seat adjustment? Wierd becasue it does not leak from the bowl vent screw anymore, but comes out the carb thoat. Any ideas?

Thanks,
Kyle

 

[Chris1956]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

There is a proper way to set the float height. Invert the cover. The top lever should be parallel with the cover. Turn the cover right side up. There should be 1/4" between the levers, as they hang down.

Is the float in cood condition? Sometimes they crack or disolve. Is the little spring on top of the float intact?

 

[Island_oki2000]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

I will readjust the top float bowl covers. As for the float, they seem in good condition. Would not seating crrectly cause the fuel to leak out the carb throat? I think when I was putting the top back in, I might have put pressure on the levers and maybe that got them out of adjustment. Should be simple to put it again and check them.

Thanks,

 

[Island_oki2000]

Re: 1975 Mercury 850 Help with Carb/Fuel Issue

Don't want to speak too soon, but I think I finally got it. I adjusted the metal pieces a bit more out and put the top back on. Pumped the primer bulb and no leaks.

I replaced the spark plugs and got it all back together. COnnected the water hose and she fired up with some trottle and the choke. She would still not idle, so after adjusting the idle needles I was able to back off the trottle until she was in neutral and going good. The idle is not real real smoth, but I had nothing to compare it to since this is the first time I've got her to idle.

I would assume for a two stroke, there is going to be some vibration with it just sitting there. I'm going to the lake tomorrow to run her a little to ensure the motor is running fine.

Thanks everyone for the help. Just have to replace the tilt trim motor and we'll be fully in business.