1977 Johnson 35 hp fuel leak

[Jeff74]

Hello Guys,

I have a 1977 Johnson 35 with a leaky carb. Engine is 35e77c. I've rebuilt the carb about 3 times following the steps in the carb cleaning page and it still leaks . Replaced needle, seat, gaskets, blown it all out. Turned it over and blew into the fuel inlet to check that the needle was holding-good. Also checked float drop-good. I don't think I can get the thing much cleaner.

Anything else that could be causing this? It idles pretty well, but will bog down occasionally at about 1/4 throttle.

I'm about ready to try a new carb if anyone knows where I can get one.

Thanks for your help.-Jeff.

 

[ezeke]

Re: 1977 Johnson 35 hp fuel leak

Did you replace the float in the carburetor and make sure that it was parallel to the carb body when you held it upside down?

 

[Jeff74]

Re: 1977 Johnson 35 hp fuel leak

Hello Ezeke,

Yeah, I did both of those things. Any other thoughts? Thanks-Jeff.

 

[Woodstock60]

Re: 1977 Johnson 35 hp fuel leak

Can you tell where it is leaking out from?

 

[tashasdaddy]

Re: 1977 Johnson 35 hp fuel leak

where is it leaking, out the throat, the overflow, it is a simple carb. i set my floats so that the unhinged side has just a little more space than the hinged side, rather than completely parallel with the body.

 

[F_R]

Re: 1977 Johnson 35 hp fuel leak

Can you tell where it is leaking out from?

That is my question too. And when is it leaking? Are you saying that gas runs out the throat when you squeeze the primer bulb? If so, there are only a few things that can cause that.

1. A defective float needle and seat, even if it is new. Or a bad/missing gasket on the seat. Or a chunk of something lodged in the seat.

2. A float that is out of adjustment, or doesn't float (heavy).

3. A plugged bowl vent. People sometimes plug them as a back-door approach to cure overflow---that doesn't work.

It has to be one of the above. Unless your description of "leaking" is something other than overflow when squeezing the bulb.

 

[Jeff74]

Re: 1977 Johnson 35 hp fuel leak

Hey Guys,

Have to go to the lake to run it, so here's what I did in my garage:

I just tried squeezing the bulb with the engine down. The bowl filled and no fuel leaked. I then tilted the engine up and squeezed the bulb (didn't really have to, it was still hard). No fuel leaked.

The fuel seems to be leaking from the throat. When I pulled the air silencer off, I could see fuel collected in it and I could see where it dripped down out of the throat from the air silencer and its metal holder and then ran out the back of the engine.

It seems to leak after the engine is running. For example, when cold, I use a little choke, advance the throttle to about 1/3 it starts, sputters and dies. Then it starts, revs up, then sounds like it loads up, rpms drop and it dies. Eventually, after a couple more tries, it will start, load up, rpms will drop, but not die until it runs smoothly at idle. At this point, I usually see fuel running down the side of the engine.

Once it's warmed, I can troll along pretty well at idle. At 1/4 throttle, it will load up again and bog down, sometimes dying. WOT is great.

Also, I found a new carb for this engine-same model # as the one on it. I went ahead and bought it. Any traps I should be aware of when I install it? I've heard about re-jetting carbs and engine damage. I just want to be safe.

This is a lot of info. I appreciate the help. Eventually, I'll get this leak figured out.

Thanks-Jeff.

 

[Woodstock60]

Re: 1977 Johnson 35 hp fuel leak

I would be inclined to check the seals and bushings that hold the slow ( and fast) needle adjustments, or the float needle is stuck IN the seat ( which has happened to me) some of the needle heads for the float are made of rubber and the newer gas corrupts them.

 

[F_R]

Re: 1977 Johnson 35 hp fuel leak

My 35 has slop running down it too. I just accept it. I guess I'm too "old-school" from when all outboard motors were sloppy and don't know any better.

Are you sure your mid-range problem isn't a sync problem? Oh well, you will soon have a new carburetor to try.

 

[Jeff74]

Re: 1977 Johnson 35 hp fuel leak

I have wondered what I'm going to do if I install the new carb and it still leaks. I think I'll have a beer, a good laugh, and go fishing!

Thanks everyone for your help. I'll let you know what happens with the new carb.

-Jeff.

 

[dade61782]

Re: 1977 Johnson 35 hp fuel leak

check this thread maybe the gaskets arent sealing happened to me once the carb flooded to point fuel was coming out the throat,vent and exhaust

 

[Jeff74]

Re: 1977 Johnson 35 hp fuel leak

I don't see a link to the thread. Thanks-Jeff.

 

[dade61782]

Re: 1977 Johnson 35 hp fuel leak

sorry here it is http://forums.iboats.com/showthread.php?t=276630

 

[Jeff74]

Re: 1977 Johnson 35 hp fuel leak

turns out a new carb isn't going to happen. I'm going to try doubling the gasket on the jet. Also, I'm going to reset the float drop so that it doesn't drop as far. Any thoughts on float drop? I'm thinking because it only leaks when running that the float might be getting stuck occasionally causing it to load up. -Jeff