Looking for carb help.. should be easy?

[norville]

Folks, I'll give you a quick background first. I have a 1980 60hp 2 cylinder Evinrude, that I bought not running correctly. So far I've found the timing off and the fuel check valve bad. I got it running reasonably well, but I have an issue with the lower carb.

The first problem was the needle was not seating, so if I pumped the fuel checkvalve fuel would spill out the carb. But it did run it just took a long time to warm up and it wasn't right it would gain and drop RPMs slowly. So I bought a N&S and a carb rebuild kit. I first just replaced the N&S thinking that was it. It fixed the issue of the flooding kinda... It ran better but if I put my hand over the lower carb the rpms would increase... I thought vacuum leak. I then pulled the new seat and rebuilt the carb the best I could. It does not have adjustable valves. I replace the N&S, the bowl gasket, the inner circle gasket , carb to block gasket, the gaskets on the low and high speed circuits, new float. But I still have a "vacuum" leak!!! and fuel is puddling up in the lower carb and it's still not right.

Any suggestions?? I believe it's a class IV carb

thanks,

bob

 

[Daviet]

Re: Looking for carb help.. should be easy?

Just thinking, if you remove the carb, drain all the gas, hold it in normal mount position and blow into fuel line nipple, should pass air. Flip the carb upside down and blow into it again, should not pass air. This tests the needle and seat for proper operation. Look on top and starboard side of carb, there are 2 little silver plugs, these are seals for jetdrilling passages. With carb back on motor and engine running, put your finger over these plugs to seal them to see if they are leaking air.

 

[Lion hunter]

Re: Looking for carb help.. should be easy?

Did the carb kit come with a new float?
Have you replaced all the lines? A cracked line will suck air.
Did you rebuild the fuel pump?
Is the tank vent open?

The rise and fall of rpm's sure sounds like air is entering the system. My guess is that it would be entering somewhere up to and including the fuel pump. Have you noticed any fuel leaks when you pump the primer bulb up? Have you tried pushing in on the fuel connectors to make sure they are sealing?

 

[R.Johnson]

Re: Looking for carb help.. should be easy?

A compression test first. How else do you know what you are dealing with?

 

[tashasdaddy]

Re: Looking for carb help.. should be easy?

http://forums.iboats.com/showthread.php?t=299680

 

[norville]

Re: Looking for carb help.. should be easy?

OK good responses. Compression is good 126/121. I feel confident I've eliminated everything but the carbs, but I could be wrong.

After the new needle and seat the both carbs will hold pressure. I did install a new ball also.

If I cover the upper carb with my hand it stalls right out, unless it's running on it's high idle rise of rpms. Put my hand over the lower and the motor pick up and smooths out.

I'll check those jet drilling holes for the leak. There's really not much to these things, so I'm a bit frustrated over this...I cannot find any fuel leaks.

bob

 

[norville]

Re: Looking for carb help.. should be easy?

bump, I pulled the carb again and popped off the "knock outs" and put in new ones. still no luck. I even sprayed deep creep over the areas looking and listening for changes. Overall it seems better but still not right and it kinda has a mind of it's own when it sitting idle then the rpms start running up.

bob

 

[Bifflefan]

Re: Looking for carb help.. should be easy?

are the carbs sync'ed properly?
the bottom one is running lean for some reason. ie: when you put your hand over the carb it runs better.
Here's a thought, try swaping the carbs around and see if the problems stay on the bottom or follows the carb. then you will know if its the carb.

 

[Lion hunter]

Re: Looking for carb help.. should be easy?

Well we've managed to narrow it down to ....nothing. I think were going to need to know (a list) of everything that has been replaced so far.
(i.e powerpacks, coils, plugs, carb rebuilt). You might also include some close up pics of your carbs when you have them off. Someone may see something missing that looks normal to you. Don't know how many plugged holes are on that carb. Sometimes they have lead shot as well as knockouts plugging the holes. All the carb kits I ever got only came with knockouts so if you were missing a lead shot you might not know it.
Did you do a leak down test when you checked compression?
Have you swapped coils?
Static timing?
Stator and sensor coil assembly looked and checked out good?
Reeds are good?

 

[Silvertip]

Re: Looking for carb help.. should be easy?

If cutting off the air to the lower carb causes the engine to smooth out you have a fuel delivery problem -- not an air leak. The mixture goes rich when you cover the carb -- not lean. You can prove this by squirting a fuel oil mix into the carb. There may be a some bad internal seals (crankshaft) that are leaking as well which would prevent the crankcase from alternately developing pressure and vacuum on that cylinder which has nothing to do with cylinder pressure.

 

[norville]

Re: Looking for carb help.. should be easy?

If cutting off the air to the lower carb causes the engine to smooth out you have a fuel delivery problem -- not an air leak. The mixture goes rich when you cover the carb -- not lean. You can prove this by squirting a fuel oil mix into the carb. There may be a some bad internal seals (crankshaft) that are leaking as well which would prevent the crankcase from alternately developing pressure and vacuum on that cylinder which has nothing to do with cylinder pressure.

This might explain why I'm still getting excess fuel coming from the carb. I'll try that tomorrow, but seafoam deep creep did not raise the rpms. I though I had a lean situation and by restricting the air I fattened it up.

Again this is an unknown engine. I was told from the PO that the cars were rebuilt they were obviously not, they still have the old style gaskets and needle seat. I used a spark checker to check the spark, and I did a compression check no leakdown test. I may swap the carbs but I'm not sure if the fuel will make it up to the upper carb. they are run in tandem.

I apologize for my lack of knowledge I much more familiar with 4 stroke car engines...


bob

 

[norville]

Re: Looking for carb help.. should be easy?

If cutting off the air to the lower carb causes the engine to smooth out you have a fuel delivery problem -- not an air leak. The mixture goes rich when you cover the carb -- not lean. You can prove this by squirting a fuel oil mix into the carb. There may be a some bad internal seals (crankshaft) that are leaking as well which would prevent the crankcase from alternately developing pressure and vacuum on that cylinder which has nothing to do with cylinder pressure.

wow you got that one. I sprayed some fuel into the lower carb and it picked right up. If I sprayed into the upper carb she choked and died. I pulled it apart again and blew and sprayed again. I will say on initial startup the motor runs very well but after about 30secs I need to raise the throttle to keep it going.

I still think it's a carb issue and I may swap them but is there any other ideas?

bob

 

[norville]

Re: Looking for carb help.. should be easy?

If cutting off the air to the lower carb causes the engine to smooth out you have a fuel delivery problem -- not an air leak. The mixture goes rich when you cover the carb -- not lean. You can prove this by squirting a fuel oil mix into the carb. There may be a some bad internal seals (crankshaft) that are leaking as well which would prevent the crankcase from alternately developing pressure and vacuum on that cylinder which has nothing to do with cylinder pressure.

is there any way to check this?

bob

 

[Daviet]

Re: Looking for carb help.. should be easy?

I hpoe I am remembering correctly and not giving you bad advice. With carb off look in the bore from the intake side, is there a series of very small holes behind the throttle plate, are they clean? Is there a brass tube from the carb body down into the bowel, it actually has a smaller tube inside, make sure and blow these tubes out with compressed air. I hope I am thinking of the right carb.

 

[norville]

Re: Looking for carb help.. should be easy?

I hpoe I am remembering correctly and not giving you bad advice. With carb off look in the bore from the intake side, is there a series of very small holes behind the throttle plate, are they clean? Is there a brass tube from the carb body down into the bowel, it actually has a smaller tube inside, make sure and blow these tubes out with compressed air. I hope I am thinking of the right carb.

yep, did that with compressed air and "deep creep" I pulled the plugs also and yes the lower cylinder is showing a lean "white" electrode while the top is brown chocolate..

bob

 

[Daviet]

Re: Looking for carb help.. should be easy?

The way it looks to me is that you have a problem on lower cylinder. Swap carbs and see if problem moves. If so you then know the carb is the problem. If the problem stays on the lower you have a crankcase or seal problem.

 

[norville]

Re: Looking for carb help.. should be easy?

I thought I'd post up, I pulled the lower carb again and removed the low speed orifice it was blocked by a chunk of something. I adjusted everything and plan to drop it in the water again. It does sound better now and if I cover the lower carb is stalls..

bob

 

[Daviet]

Re: Looking for carb help.. should be easy?

Ain't it funny how a overhauled carb can have trash in it. Has happened to me several times, usually because of fuel lines coming apart.

 

[norville]

Re: Looking for carb help.. should be easy?

that was it, it runs great. A shame, it was unusable for 2 yrs for the PO.

bob