For an engine to run you need air, fuel, compression and proper timing. If you know for sure you have spark and fuel, check timing. I'm assuming it has compression since it's trying to start. It may be low since the cylinders are getting washed from the fuel being pumped through it.
Good luck and keep us posted to what the problem was,
Scott

PS. can you keep it running with carb spray? If so, look at having a fuel delivery problem.

Scott Ward

2 1948 1.5-ton Loadmasters
The red one and The snow pusher
1 1950 3100
1 1955.1 Chevy 6500
1 1954 Chevy 6500 2-Ton
1 1955 1st Series COE 5700
1 1963 K20 (454)
1 1964 C10 (350)
1 1951 1.5-ton Dump Truck
1953 and a 1956 Ford F800

Raising a teenager is like trying to nail Jello to a tree!