spray a cuppla shots of rattlecan carb cleaner down open carb throat. Quickly crank engine. If engine tries to start (pops), you have a fuel delivery problem.
If no engine start effort, you have an ignition/timing issue.

When you rebuilt that carb, did you use a magnifier and a thin brass tag wire to probe ALL passages/orifices - and then blow out with compressed air ? If not, still a good chance one or more are plugged/clogged...

this link will provide some carburetor guidance concerning fuel leakage through the fuel nozzle. This could be allowing too much fuel into the engine. The carboned sparkplug is a clue that indicates rich mixture.
http://www.perr.com/tip9.html

Perform a spark test on the ignition system to see if this is the cause of the NO Start condition. If the ignition system is strong, the voltage could be following the carbon on the sparkplug instead of jumping the gap. Try another sparkplug if this is the case.

Thanks for the replies!

When I rebuilt the carb, I did check all the passageways and blew them out with compressed air. I checked all the seats and cleaned them with a q-tip if possible. None looked bad, but the float needle seat, which isn't easily replaceable, has a rubber type of seat that seemed to be in good shape. I probed it gently with a cardboard q-tip shaft and it is still soft.

The PER notebook link is interesting, I'll recheck and if need be relap the nozzle seat. Maybe I'll get lucky and have it running like it should this weekend, though I won't have much grass to cut due to the drought.

I will check the float level and also see if there is any possible gasket interference. There doesn't seem to be any warpage, but I'll check it with a straightedge.

Once I have the fuel leakage figured out, I'll try a new sparkplug, as the old one wasn't worn, but has plenty of carbon on it even after cleaning. And if I can't get fuel into the engine, I'll try the starting fluid.

Thanks again!

vince

I ran into a Briggs carb recently with the same leaking problem. I replaced the needle but not the seat. One buddy recommended using the old needle and using valve lapping compound on the tip to polish the seat. It dramatically slowed, but did not stop the seepage. I just installed a fuel shutoff valve on it and told the owner to religiously use it.

The seat removal isn't too bad according to a google search. Look it up.

you can pop the old seat out with a short blast of compressed air into the inlet pipe ,use a shop rag to catch it. Then you can inspect/replace.To reseat use a small nail head to push it down evenly.

I've removed the seat on that carb (or similar) with a bent-at-the-very-edge microscrewdriver from Radio Shack. Bent it for this purpose years ago. Worked like a charm. Air Compressor works well too of course.

I missed the part about the rubber type needle seat. I was talking about a brass seat.

I got an additional kit at the NAPA store with a new rubber needle seat and needle. I'll put them in tomorrow and I get the feeling that will be the beginning of the end of my carb issues. I'll post an update when I have one....thanks!!

vince

Check first if the seat goes in a certain way. On Tecumseh carbs, there is an up and a down side of the seat. Their grooved side goes down.

Yes, got it all put back together... The seat has a grooved side and a tapered side, so it's easy to put in the right way so the tapered side meets the needle valve.

I still have an issue with some fuel seepage at the base of the main body where the plate is staked in, and leakage at the needle valve. I have the float about 1/16th of an inch low (according to the instructions it should be parallel with the throttle body). I would think this makes the float sit low? This is how it was before I got into it. It occasionally starts for a bit, runs rich, but before I can get around to tune it, it dies out.

I'm thinking first I need to make sure the float height is correct to stop the leakage, then make sure the various adjustment screws are in the correct position. Rather than trust only the vague instructions, any comments on the settings for the below screws/levers for starting?

Needle valve (#turns out??
Idle Adjusting Valve (# turns out?)
Throttle Stop Screw (# turns out?)
Throttle/speed control?
Choke

Thanks again,

vince

Well, the ball park settings for "needle valve" and idle air valve are 1 and a half turns out from the fully seated position. Then you will just have to "mess with them" until you get satisfactory idle RPM performance.
The throttle stop screw should only be turned IN until it allows for the engine to idle properly. If it is turned IN too far, the carburetor begins to operate off of the main fuel circuits, and that can interfere with your adjusting the actual IDLE CIRCUITS (air and fuel) when you are trying to tune the carb for proper idle mixture.

Bear in mind that the lower the float level is set....the lower will be the level of fuel in the bowl.
And also recognize that means when the carb is held upside down for viewing the float level setting.....a wider gap adjustment means a LOWER float setting.
You are not really done setting a carb until you operate the machine under normal conditions and then remove the spark plug for a "color reading".
Black and sooty color means it's set too rich.
Tan to light brown is about perfect.
Gray to white is too lean and will lead to engine damage if not corrected.

Thanks Mownie. I'm getting the idea that the real issue may be elsewhere in the engine as while the carburetor was in need of a cleaning and readjusting, it also wasn't that bad and didn't have any damage. I do agree that the final fine tuning is done with the plug color, but wanted to get the engine set to specs and running first.

vince