MCCULLOCH Mac 10-10 mystery fuel leak

[moshra]

This one has me stumped so here I am asking for help. I'll try to cover all the usual suspects:

1- Tank gasket replaced. Fuel is confirmed not to be coming from there.
2- Fuel line and filter replaced, where the grommet exits the tank has had seal all used around it. Twice. Confirmed it's not leaking from there.
3- Fuel cap is rebuilt and the vent is functioning. Confirmed fuel isn't coming from there.
4- Carburetor is a Walbro SDC 65 and has been completely cleaned and rebuilt.
5- New spark plug and gap is set to recommended by the shop manual.
6- Compression is strong, saw hangs by the rope with a 20" bar and full tank of fuel. Compression is confirmed 146 PSI.
7- Saw usually starts in 1 pull if I'm quick enough to push the choke in. If not it will start on the second or third pull.
8- Saw runs good and cuts good. No weird erratic idling, 4 strokes out of the cut like it should. Will restart in 1 pull no problem.
9- Idle stays the same when rolled onto it's sides.
10- Have experimented with different fuel levels in the tank. Above the fuel grommet, below it, and even below the tank seem. Strangely the leak seems to be the worst when it is below the tank seem.
11- The fuel seems to be coming from the right side of the carb in relation to the intake as you look towards the bar.
12- Carb and fuel line tested from fuel hose in tank. Holds 10 PSI even while moving line around.
13- I noticed fuel pooling in the carb chamber when I first got the saw and assumed it was either the fuel line, carb needing a rebuild or tank gasket. So the problem was there before I did anything to it. It also ran and started decent before I bought it but definitely starts and runs better now after the work I've done. It's just this mysterious fuel leak.

I am absolutely baffled by this one. Not my first rodeo but is my first Mac. Why would the carburetor be leaking but still start and run ok? I'll try to attach some pics for what little help they might be. The red you see is the fuel, I use red armor. Any help is appreciated. I'm always learning but man this one has got me scratching my head.

 

[hacskaroly]

This one has me stumped so here I am asking for help.

Yeah, you have covered everything I could think of and without it sitting in front of me so I can look it over it is hard to tell what else to check. I wonder if you cleaned it up, started it and then held it bar down if it would still leak (or leak more than normal), same with holding it bar up. Not sure if that might help get a better idea of where it is coming from.

 

[jacob j.]

Is your inlet needle lever set too high? Which carb does it have - SDC?

 

[moshra]

Yeah, you have covered everything I could think of and without it sitting in front of me so I can look it over it is hard to tell what else to check. I wonder if you cleaned it up, started it and then held it bar down if it would still leak (or leak more than normal), same with holding it bar up. Not sure if that might help get a better idea of where it is coming from.

Tried it bar down, didn't leak. I'll try bar up. This saw has me scratching a bald spot in my head lol. It looks like fuel is coming from somewhere on the right side of the carb ABOVE the fuel inlet. I have no idea what would cause that though. Also doesn't seem to leaking while running. And seems to leak more with the fuel level BELOW the tank seem. And the leak seems to be intermittent which is driving crazy. So frustrating

 

[moshra]

Is your inlet needle lever set too high? Which carb does it have - SDC?

Metering lever height is set to factory spec with factory walbro tool. And it is an SDC 65 as stated in my original post.

 

[jacob j.]

Metering lever height is set to factory spec with factory walbro tool. And it is an SDC 65 as stated in my original post.

Try going a touch lower with the lever. I'm assuming the metering diaphragm and fuel pump gaskets/diaphragms are in the correct order?

 

[Sloughfoot]

Would a leak like that show up with the carb pressurized under water?