2004 200hp fuel issue

Hey guys Im trying to help a buddy of mine with his boat. He has a 2004 200hp 4 stroke yamaha. I was running great when one day the pick up in the tank got clogged up. After switching to a small 6 gallon tank and verifying the fuel supply was sound it continues to start and die. Applying the throttle will initially rev it then it dies again. Sometimes getting a pop through the intake. I pushed the shrader valve on the fuel rail and there was hardley any pressure in the system, even while cranking. What kind of pressure should there be with the key on engine off? We checked the small filter under the cowling and even tried without the element installed.

thanks for any help, will

Key on engine off you should have a minimum of 38lbs of fuel pressure right after the pump cycles. If any debris has passed the filters and gotten into the vst and the injectors, you will have to completely service the fuel system injectors and all.