mercury 225 update

[Bass_Appeal]

Yestarday morning , we worked on the merc again. We took the vst off cleaned that again , the intake and injectors,2 injectors were not working so we cleaned the terminal to those and switch some around to different cylinders. They are working now ! On the vst oil check valve was clogged we cleaned that. Now all cylinder are firing properly. We decided to take for test run and see if the work we did solved it all ...dipped her in and took off after about 15 seconds and 4500 rpm she stalled and died. Started right back up and idled fine ...ran another 10 seconds at 4500 and she died .....started right back up .....then we primed the ball went another 20 seconds and died ....primed up went to 4500 and manual pumped ball as we were going .....no stall till we stopped pumping manually. Opened the fuel cap and tried again. Went about 15 sec and died ....ellimanated the vented problem ....then we decided to check the check valve at the pick up ...there was a piece of solder from the tank lodged in the elbow , took it out and tried again same issue 15-20 sec and died .....
todays goal after work is to completely remove pick up and inspect....take the pulse pump off and inspect (even though i just rebuilt it ) and primer ball inspect ...after we determine which is the cause i should be back to normal.

Quest. 1 .
How can i prevent anything in the tank from being picked up ? Some may say drain tank but if you drain the tank the solder chunks will remain !
And cant just tank the tank out cause you have to cut it out and redo all of the fiber glass

Q.2
Whats the easiest way to tell if the ball it self is bad ?