Difficult Start: Carbureted

Ensure sufficient secondary spark is available.
Ensure fuel level is at specified mark on carburetor sight glass.
Ensure fuel system pressure and volume are correct.
Ensure fuel filter is unrestricted.
Check for correct vacuum hose routing.
Check vacuum hoses for kinks or poor connections.
Ensure engine has sufficient compression.
Ensure ignition and valve timing are correct.
Verify choke valve is closed (engine cold).
Verify choke valve is open (engine warm).
Verify noise suppressor has correct resistance.
Check charcoal canister operation by clamping hose(s) shut. If problem discontinues, check vacuum hose routing. If routing is correct, replace charcoal canister.
Ensure that the vent switching valve is closed when the ignition is off.
Ensure winter grade fuel is not being used in warm climate conditions.
Ensure exhaust system is not restricted.
Ensure that ECU is properly grounded.