1998 merc 150hp boggin down

[waltdiggity]

Only boggs when driving onto trailer. Took off carbs had floats are perfectly level with bowl when turned upside down. will run good all day but when driven up on trailer will bogg down within 2-3 minutes under high or low rpms. has anyone seen this before?

[boats.net]

Check fuel pickup tube in gas tank and antisiphon valve at gas tank.

[waltdiggity]

fuel pick up tube is clear and anti siphon has been removed. primer ball stays full when problem occurs.