So I reinstalled one of the fuel tanks, connected the new fuel lines of equal length from both tanks to the T valve and ran it to the "mechanical" fuel pump which now is not pumping fuel. Mind you this new fuel filter had water in it before I removed all of the fuel and cleaned the tanks. The odd thing is I ran the tanks separately and it pumped fine. Now with both hooked up there is no fuel flowing to the filter. 
Could it be this new fuel filter was damaged although I don't see how if I successfully ran both tanks separately and fuel flowed thru? 
I am able to keep the engine running as long as I keep the carb's float filled all the while no fuel is being drawn from the tanks.

My next step is to disconnect the high pressure line and see if there is blockage from the pump to the Quadrajet carb.
Any other suggestions?

Found out I have a lot of moisture in my fuel line. What is the best way to clean out my fuel tanks? They are on each side of the boat, do not have tube which unscrew from the tanks.

Hello,
Newbie here as well as my first post. Don't laugh but I have a question involving the proper procedure running water thru the engine in order to run the motor while the boat is on the trailer. Is there a connection for a hose? Is there a devise which hooks up to the jet intake as in outboard motors.
Although I am mechanically inclined, I've never worked on this type of set up. My friend wants me to find out why his boat suddenly dies after running for about five minutes on the lake. I suspect it's the fuel filter as the boat has been sitting for about a year. We've added new fuel as well as seafoam so the fuel shouldn't be a factor.  I simply want to run the engine while it is on the trailer and assess from there.
the only thing I now about the boat at this time is that is is a 1973 with a Buick V8 engine. I'll find out more is need be.
Thanks in advance!