Help! fuel in crankcase ( lots )

Hey guys i did my headgaskets last week and just put the truck back together and fired it up everything worked great easy to start, then shut it off to check for leaks ect. and went to restart it and it cranked a bit more than usual and fired was running fine but i noticed that my fuel gauge was droping quickly so i shut it off and drained about 10 gallons of fuel oil out of it. this was in the first 5 mins of running so i pulled the valve covers off but cant find a loose return rail bolt or anything. is there any way to pressuize the system without putting it all back together to find the leak? because i have the ICM off and the fuel filter as well

thanks guys !!!!