No spark and fuel pump does not prime when key is on

Ok I bought this boat from a action it is 2003 Mariah sc22 with Mercruiser 5.0l V8 305 1999 and up with Alpha drive. So the people left the batterie on the boat connected so the so the main starter terminal fell a part. I replaced the the starter and changed the wire. I also replaced and put a new ignition switch that i got at auto store. So then i tried to crank the engine i was getting no fuel i took the fuel pump off hit it few times it started to work but it would over flow my carburetor then i took the carburetor off had it rebuild it still would over flow then o went and bought a low pressure pump from napa that is marine grade then i checked for spark it looked like i have the spark then more into troubleshooting i found out my spark was good only for few seconds not even enough to start the engine then i tried to see if the fuel pump works when key is on to prime it self it does not it only works when you cranking the engine so tried to by pass to see if it works it does. Then i changed my safety switch i thought may it was it no. Still no spark i change the rotor new cap and ignition sensor inside distributor, i do have power at the purple wire on the coil i also have 12v at the white/red wire coming from ignition module. Could these two problems be related any help please. To what should i look at.

Re: No spark and fuel pump does not prime when key is on

Welcome to iboats! How long has the boat been sitting before you purchased it? First things first, start reading the "adults only section" and "must have technical info" at the top of the thread. There is invaluable info there that will help you diagnose most issues. From experience I can tell you that you need to go back to the basics to get this engine running. You need 12v at the coil so run a jumper wire from the battery to the + terminal of the coil. Then you need to remove the grey wires from the - terminal of the coil. That should bypass any shorts you may have. Then you need to connect a remote gas tank to the carb to rule out any issues with the gas. Re-reading your post leads me to believe you have an electrical fuel pump but you didnt state if the new pump fixed the isues you had.

There is an unbelievable amount of knowledge on this site and everybody here is more than willing to help. Post very specific info and pics to make sure you get the correct answer for your specific problem. Do Not Give Up!!!!