Carb still leaks.....76' 55hp....lower carb

[JSGOLD]

Worked all day trying to get the lower carb to stop leaking...so luck. I rebuilt these carbs late last year, bottom one will be OK but then fuel wells up in it and it starts dripping here and there. I rarely use this motor as we live near hp limited lakes so I dealt with more pressing issues at the time and now am trying again. I checked the float levels, welch plugs, and pumped pressure into the system. It pumps up OK and seems to hold. I removed the carb and turned it upside down / right side up. and blew through it and at first I thought it was OK...however I seem to be hearing a very VERY slight noise when upside down. More of a slight hiss, but hard to tell..... So I am not sure if the needle is bad or maybe something else is eating on it. Are there any gaskets on this carb that could let fuel into the throat when running? The only two I see is the little round one at the base of the bowl and the bowl gasket itself. Any good tests you guys could recommend with this thing? I am no expert on outboards but have rebuilt many a small carb before and not had the trouble I have had with this thing.

 

[Cap'n Chaos]

Re: Carb still leaks.....76' 55hp....lower carb

Take a look and see what you are missing.

http://shop2.evinrude.com/Index.aspx?s1=fgtugkvri84j6gfqth7qa5fj06&catalog_id=0&siteid=1

 

[Daviet]

Re: Carb still leaks.....76' 55hp....lower carb

Double check your needle/seat and make sure there is not a small piece of trash or something holding it open and make sure the float level is correct. You should be able to turn the carb over and blow into the fuel inlet and not pass any air.

 

[JSGOLD]

Re: Carb still leaks.....76' 55hp....lower carb

Nothing missing...all parts there and changed out. I d/c the needle assembly and clean as a whistle. I am not 100% it is passing air....it kind of sounded like it had a leak but I was so darn tired it may may been me making the darn noise....I know it holds pressure OK. although I don't know how long. I have only run this motor 3-4 times, and only twice for any length and it has never run right. PO advised me it needed a carb job and when I tore them down they were pretty clean and looked to have been rebuilt several years ago. It leaked fuel the last time I ran it and I shut it down and ran the kicker. I was thinking perhaps the little gasket at the base of the carb bowl may be letting fuel in somehow, maybe even though I d/c it the welch plug is not 100% tight, or maybe it is a sign of something worse like a cracked carb or bad reed assembly. I would think as slow as this wells up it would be drawn into the cylinder.....Maybe I just need to start over and maybe start some additional tests such as compression etc. I know it sparks OK at startup but I also remember the last time we really had it going...we had it at Stonewall Jackson Lake and opened it WOT and it steadily gained speed and RPMS and then it lost power. I figured I lost a plug so we shut it down and ran the 8HP kicker the rest of the day. Would a coil kicking in and out cause something like this??? Just wondering. Anyway, I was looking for any tests anyone had in mind that might be helpful.

BTW the floats are level when "up".....I tried adjusting to have it seal a little earlier with no luck....

 

[Joe Reeves]

Re: Carb still leaks.....76' 55hp....lower carb

Leaking carburetor..... If you haven't installed a new float needle valve assembly, do so.

(Carburetor Float Setting)
(J. Reeves)

With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.

 

[JSGOLD]

Re: Carb still leaks.....76' 55hp....lower carb

All new parts. I adjusted the float level, then slightly elevated and still fills up. I am missing something here just not sure what....Would the needle valve stop 100% of the air if I blew on it or could enough pressure let some by? I am thinking of hooking a hose to the carb and putting it in a pan of water to verify air leakage...as dumb as that sounds. I can always clean the carb as most likely I am going to have to rebuild it again.

 

[JSGOLD]

Re: Carb still leaks.....76' 55hp....lower carb

I may be chasing a problem that is in turn, something else. The amount of leakage is small and takes a little while to show up. I would think the cylinder would "suck" fuel from the throat into the engine...perhaps a reed valve is out of whack...hard to say with this old motor.

 

[Daviet]

Re: Carb still leaks.....76' 55hp....lower carb

A properly adjusted float will stop all air if you blow throught it as long as the needle/seat is not damaged.
There shouldn't be any fuel puddling in the carb throat.
You replaced the washer under the new seat didn't you?

 

[JSGOLD]

Re: Carb still leaks.....76' 55hp....lower carb

Yes to the washer......After working with it again this evening I see no air coming out during my tests. I even submerged the carb and blew trying to induce bubbles, nothing. The more I look the more I am convinced something else is eating on this engine. I read my manual and it looks like everything replaceable has been replaced except the carb bodies... I have switched needles and seats, adjusted the float and nothing seems to work. This engine has to run for a while before the fuel appears, and I wonder....could any of these cause fuel to "pile up" in the throat.....Reed valves dirty, bent.....Carbs no in sync...maybe at idle the lower carb throttle plate is closed and not letting fuel in....poor compression on that cylinder, misfiring due to poor spark on that cylinder, rich idle air mixture, ....since there are two carbs could the top one be doing something wrong to do this(don't see how but asking)???????? I have been through it three times.

 

[Joe Reeves]

Re: Carb still leaks.....76' 55hp....lower carb

Could be.... pull the intake manifold and dismantle the leaf plate assembly. Might even be something as simple as a small particle preventing a leaf from sealing properly. If it was anything wrong with the carburetor, fuel would flow from it as soon as you pumped fuel to it.

 

[JSGOLD]

Re: Carb still leaks.....76' 55hp....lower carb

UPDATE.......FIXED

This is where knowing more about these motors and being more thorough would have saved me a LOT of grief.....I removed the top carb, and took a look at the leaf plates with a bright light, just to see if anything obvious was there...YES THERE WAS. I found to my horror a air box screw sitting in there stuck in the bottom set of leafs....Carefully removed it, assembled the carbs and fired it up...No leaking! It runs better too! I had to fiddle with the idle screws as I had them out of whack with the testing but it sounds great. I will have to do more fine tuning later but for now we are looking forward to using it this weekend at our annual crappie contest. We were prepared to use the 8hp kicker but this will get us where we need to go faster. I only wish I had known enough to peek inside the leaf area before...would have save a lot of headache and who knows what would have happened if that thing got sucked inside....The air box was missing screws already so I don;t know who did it, but at this point I have learned a lot....When you remove the carbs, LOOK AT THE LEAF PLATES.......Thanks!

 

[Daviet]

Re: Carb still leaks.....76' 55hp....lower carb

Glad you found your problem, and good luck with your contest.