Briggs 14.5 hp 42A707 won't start

I've been pouring over old threads to no avail so I thought I'd start a new one. Here's what I've been facing. MTD Lawn Chief with a Briggs 14.5 hp engine (42A707 2238 E1). The engine has always run rich (based on how I smell after mowing). This season has been no different until one day when I went to mow the yard and got nothing when trying to start--no click, no engine turnover, nothing. I thought maybe the battery was dead, but had just bought a new one this year. After a little searching I figured maybe a safety shutoff since I was getting nothing at all. Checked them all and cleaned out any debris. Also checked solenoid near under plate near the seat, everything looked ok. Thought I'd go ahead with a tune up, so replaced spark plugs, cleaned and rebuilt carb with kit, and blew out grass and other debris from engine. At first, it was hard to get engine to catch and start, but I finally got it running. Next day, it fired right up, but between the garage and the front yard engine sputtered and died and I haven't gotten it started since. I've rechecked the carb, cleaned fuel filter, and put on new gas lines with a shut off valve. Thinking oil might be an issue, I drained the oil, which was full of gas too (maybe from too many attempts to start?), and put in fresh. Still no dice. Engine turns over nicely but absolutely won't catch and start. What am I missing?

 

If there was gas in the oil, the needle is not stopping the gas flow into the intake. Based on that, I'd say the engine is flooding.

 

Very possible, though i put in a new needle with the new float when i rebuilt the carb. If its not the needle itself, maybe the jet it plugs??

 

From your chronology of fixes it sounds like the carb's inlet needle is flooding. On the first day after the carb overhaul I would assume you did not have the shut off valve engaged the entire time and fuel leaked through the carb, then into the combustion chamber and eventually into the oil. You said it took a while for the engine to catch. This is a flooding symptom since it take quite a few revolutions to blow out that liquid fuel before the motor can start. Next, I assume you DID engage the shut off valve, so when you went to start it the next day there was no liquid fuel in the combustion chamber and it started right up.

This leak, however, must be a big one since when it was actually running it could not use up all the fuel leaking by the inlet needle and the motor flooded, while in use.

That is what it sounds to me, happened. You will need to remove the carb and if I were you I would change the seat as well, if you have not already done that.

When you are done, I always give my carbs the blow test before I reinstall them on my motors. I hold it the right way up and with my mouth, lightly blow air through the inlet nozzle. Air should flow freely. Now I turn the carb upside down and blow air again and it should be fully restricted. If not, fix it again. That valve has to allow fuel in AND shut fuel off.