As Steve said, check for spark. (However, you must have a working ignition primary pulse for the pumps to run...)

I remember chasing a no-start 740 some years ago, and in fact it became a "brain teaser" for the BB.

Long story short, lots and lots of cranking had washed enough oil off the cylinder walls so the compression pressure had dropped -- and even with spark and fuel, it wouldn't fire up.

A few squirts of oil in each plug hole fixed that, and it stumbled to life. And exhausted clouds of smoke for 10-15 minutes.

If this works for you, be prepared to change to oil. No doubt all that gas is now in the crankcase, diluting the oil and creating a fire hazard...
--
Don Foster (near Cape Cod, MA)