Just to add some confusion to the thread....why are there only 3 hoses? Doesn't the engine have a return hose back to the tank for the diesel overflow? If you're boat is equipped with a 'lift pump', meaning it's not feeding fuel to the engine via gravity, but rather, it's assisted by a low pressure electric pump plumbed in line between the tank and the engine (typically between the primary and secondary filters) ...well if it has one of those try this...When the key is on and the engine is not running...listen carefully to the tank....do you hear fuel dribling back into it? If you do, it's coming from a 4th hose to the tank.
Now this may have nothing to do with the problem on the surface, but it may suggest you need to take a much closer look at the plumbing to get a deeper understanding...in hopes of improving your diagnosis.
Last edited by Pub911; 06-23-2008 at 11:09 PM.