Hello, this is my first post here and I wish to share a problem I have starting my boat engine, with hopes for helpful suggestions.<br /><br />I have a single 1991 Mercruiser 7.4L Bravo I/O with 670 hrs., electronic ignition, Quadra-jet carb, raw water cooled, installed in a SeaRay Weekender 250. The mechanicals have been rigorously maintained by me for the past 8 seasons, using only OEM parts.<br /><br />Last weekend, the engine took in seawater from the exhaust outlet pipes while backing down in a following sea. I had removed the exhaust shutters the prior season and did not replace them per a local mechanics recommendation.<br /><br />After pulling all the plugs I blew excess water by cranking the engine till dry and injected storage seal into each cylinder. When I removed the 3" riser blocks, I discovered that water had also seeped into the dry ports (both sides of block) between the gasket and manifold due to surface errosion. It was necessary to replace both manifolds, 3" riserblock kits and all gaskets. The riser heads are stainless and were in perfect condition. During reassembly, I also installed new exhaust shutter valves, new distributor cap and rotor, new AC plugs, bought two new group 27 batteries and cleaned all electrical contacts. The cables were new in 2002.<br /><br />For the past two days, I have tried to restart the engine but only get a moderately slow cranking. There is a weak spark from the plug cables when tested against ground, a strong spark when testing the coil lead and gas is getting to the spark plugs, evidenced when removed. I am stumped along with two mechanics I have spoken with. <br /><br />It stinks being dead in the water at my marina during a week of vacation and cruise plans cancelled. Any ideas . . . please? 
