Merc 5.7 2bbl 1998 unique concerns.
 

This is a buddys boat. Was always a turn key boat. He always assumed it was fuel injected. Anyways,he goes to sell it. Takes new buyer out for test drive. Unit will run and idle cold for a bit then it will run and get on plane under load. then the unit wont idle long enough to get into gear. concern seems intermittent. It will idle then not. I have only done some visual inspections. found the electric choke operates properly. (which would explain the ability to idle cold) I did have a new sealed pickup module for a distributor. I told him to give that a shot.

It has a 2 barrel edelbrock/weber looking carb. Im leaning toward a blockage in the idle circuit or fuel quality. He is now saying it wont run under load after pouring sea foam in it. i need to get my hands back on it but have been busy. wondering if anyone has had similar issue or a known concern with this fuel system. 5.7 alpha 1998

Check the electric fuel pump, they are pretty common for failure on those.

He may need a carb rebuild if he runs fuel containing ethanol.

Second the fuel pump.