[miker98038]

I don’t know about the Merc’s, but my 55 bird had a “sock” or filter in the tank on the pick up tube. Loose debris would get sucked onto it (a handful of old raffle tickets) and the car would die. No suction, they’d fall off and away I’d go. I doubt you’ve got raffle tickets, but maybe a plugged sock choking it off? Long shot, and like I said I don’t know if Merc’s used them.

I might pull the cap when the tank wasn’t full, and put some compressed air on the line from the pump back. See if anything blows clear. Low pressure, not 100 psi.