Please help. 1995 mariah talari 4.3l mercruiser cold start issues
 

Hi everyone I am a new mariah owner. I am having some issues starting my 4.3l mercruiser from cold start. I have been running throttle only and pumping 5 or 6 times then pulling back halfway. Start cranking and it fires up but no matter where I place throttle it will run for 10 seconds and die. The only way I have been able to get it to start and stay running is by dumping a small amount of fuel in the carb once I do this it starts and stays running. When shut off after initial start it will always fire right back up. Am I doing the cold start sequence wrong should I be pumping more first? Seems as if it runs out of fuel but I have pumped 25 times and it still won't start initially unless I dump fuel in the carb. Or could this be a choke issue such as it not opening properly after initial start and choking itself out? Any help would be greatly appreciated.