Hey guys . So last week got the boat ready for the water ( weather here has been crap) . Boat started up just fine and let it run 2 mins or so . Now my brother owns a service shop and we have done a ton to this boat . So , was running fine then idled down and died , started again and ran for about 30 seconds then turned it off . Went to the lake , wouldnt start , would crank but not start . Looked at the injector pulse and they are shooting fuel however my brother said not enough to get her started . Went back to his shop . Push a Pressure guage on the fuel line ...went to 30psi bouncing then slowly dropped and engine died . Pulled the fuel lines off the low pressure pump and no fuel coming from tank . Blew out the lines, checked the connection on tank , cleaned all those . Pulled the filter off the High pressure pump , filled with fuel , started right up and held at 30psi with out issue ...was running great . My brother suggested moving the Low pressure pump to the rear of the boat close to the tank since they are not meant to SUCK fuel as they are to PUSH (pump) fuel . He said he doesnt understand why they do this in marine applications . So i got home , moved the Low pressure pump to the rear of the boat , new line from tank to pump and used the existing line to connect to the High pressure pump up front . Vented the air by turning the pump On and Off listening till i heard a good solid sound at the High pressure pump. Boat started right up and idled great . Put the FAKE LAKE on the boat and went to start ....SAME DAM ISSUE wont start now, just cranks . My brother is saying take the line off to the High pressure pump and cycle the fuel pump to make 100% sure fuel is reaching the HP Pump . Have yet to do this

Any thoughts as to what else it could be ?