Yes it is. One of the little flaps is worn out. Will that likely cause the issue of it not starting?

csigona

When you wrote above "nearly a minute before stopping", I presume you mean that it ran out of fuel, not that you deliberately stopped it.

Yes I believe it ran out of fuel as I didn't touch it. That's where I'm assuming it ran longer due to me half filling the little well in the tank. So guessing fuel isn't being sucked from the main tank into the little well?

https://outdoorpowerinfo.com/repairs/

The flaps are the one-way valves. In one direction, fuel pushes against it and it opens; in the other direction, fuel pushes against it but the flap hits the metal so it doesn't open. That's how it's supposed to work. What's probably happening for you is that a sip of fuel is sucked up the long tube, but then is pushed back down the same tube, so the fuel never moves further over to the well.
 
So the answer is yes, that would cause the engine to stop. Get yourself a new diaphragm gasket.

Thanks all,
Ive replaced the diaphragm and sprayed the carburettor out with a carby cleaner and now it’s running perfectly.
just need to do an oil change as it’s been sitting in storage for 5yrs+.
assuming it’s just a case of plugging some hose onto the nipple and loosening the bolt to empty out all the old oil?

You can remove the bolt and catch what you can (making a mess). 
 
If you drain the fuel tank, (or at least remove the air filter), you can tilt the engine
and pour the old oil out of the filler hole...
 
 
 
.