I just recently took my 1955 Mark 25E apart. There are two lines that need to be routed correctly so the crankcase pressure can properly pulse the fuel pump. Please see the photos below for the proper routing of those lines. The other two lines are for the fuel it self. The fuel pump is marked "IN" where the line from the fuel connector runs. The other unmarked hole is hooked to the carburetor. Hopefully this helps. If you need additional pictures please let me know. Best of luck to you!
