[HO455]

When you say a long crank how long are we talking about?

Today's alcohol infested fuel will evaporate faster and more completely than the fuel of yesterday. This can empty the float bowl of combustible liquid causing the condition you are experiencing.

There is no need for check valves. The fuel enters those carburetors from the top of the float bowl so the fuel cannot drain out.

Old rubber hoses on the suction side of the fuel pump can cause it to suck air and not pull fuel properly making for longer cranking to get fuel to the carburetor. The small air leaks will allow the fuel in the line to siphon back into the fuel tank when the truck is shut off. Making even more work for the pump on start up.

I agree with BigBird05 as to the first place to start looking. Then I recommend a careful inspection of the fuel lines. If all is good then pulling the sender and inspecting the lines for damage and making sure the sock isn't plugged.

Good luck and please keep us updated.