I got this boat cheap, it's my first boat, and I'm having issues getting it running. It will start and run ok for a few seconds but then die. It seems like it runs out of fuel. I've got a new fuel pump diaphragm on order and a new gasket for my tank which is leaking a bit. I'm new to outboards, any advice on what else I should look at, a local shop said he won't work on this engine because it's too old. It seems really clean and no discoloration on the head, so Im not willing on giving up on it. Also, after I tried for a while to get it running, I noticed some sludge coming out the exhaust area, any ideas? How do I know if I need to replace the impeller.