Briggs engine will not start and dealers in my area are 1 week out to even look at it.
Employees said it would not stay on yesterday
Will not start at all today
Will not even attempt to start 100% dead
Oil changes on time every time along with oil filter.
Spark plugs changed last month
Inline fuel filter changed last month
Spent last two weeks in underground garage with poor airflow.
Does it turn over with the key? Just not fire?
Gas engines in general need four things to operate…spark, oxygen/air, compression and fuel.
Back in the day we used to unscrew the spark plug(s) and ground them to the block and check for spark. Not sure if that’s possible on the Vanguard but one thing to consider.
The only thing the key does is engage the clutch nothing else. It’s doesn’t try to start just a simple click of the clutch and nothing else
Pump seized?
8gpm. I have 250hrs on this unit with no problems until now.
Check if it will start with a squirt of carb cleaner or starting fluid. If so, theres a fuel issue. Maybe a fuel cutoff solenoid not working.
That was my next thought, starter solenoid. Try another battery too.
Sounds like dead battery or solenoid issue.
Going to switch batteries with another unit and if that doesn’t work going to try the solenoid
Does it have pull start in addition to electric start? If so turn key to on and try the pull starter. My apologies for being repetitive if you already have. Sometimes it’s the basics that kill you.
If it’s not cranking at all it’s more than likely electrical. Do as @Sasquatch said and turn the key to the run position and try pull starting. If you’re able to pull it that means your engine isn’t locked up. That’s when you focus on electrical. If it turns over but doesn’t start go buy a spark tester. You can get them at any auto parts store for around $10. They plug inline with the spark plug wire and spark plug so you can monitor spark. Be sure to check both coils. Although, a twin cylinder can usually run on one cylinder.
Good chance just have a weak battery.
So one of my guys tested the pull start earlier, but after I changed out the battery and fuse and still nothing I tried the pull start and it came on. I bet he didn’t have the key turned on when he checked it.
Lol. I’d have a hand brushing party the rest of the day for your guys, after that boo boo. 
When you turn the key off it grounds out the coil to kill spark which in turn shuts the engine down.
It’s either the battery or the starter. Sometimes the little gear on the end of the starter needs replaced. The teeth can break or round off too much. Replacements are pretty cheap.
Same guy ran over a door stopper with my surface cleaner today popping one of the nozzles off lol. He actually is a very good employee just a rough day for him.
