I have a 94' Mercruiser V8 350 engine in my boat (21' chaparral). For the
past year I have had some difficulty starting it. I dry dock it and when I
start it up on the hose in the beginning of the weekend to make sure
everything is working before taking it out, it's extremely difficult to
start, I usually have to put it in neutral and pump/push it forward and back
maybe 5 times then almost put the throttle all the way forward for it to
start (and still it has to crank for a about 5 seconds before it starts),
once started i run it at maybe 2000rpm for a minute or two then I can put it
back to idle and no problem. If I let it run for a while the next time i go
to start it, it turns over perfectly.... Now when I put it in the water an
hour or two later, i have the same problem except it is magnified and more
difficult to start.

Things I have done: Check the plugs / regap, outdrive serviced / impeller
etc...

My thoughts are that it probably isn't the plugs because I would have a
difficult time starting it weather it was warmed up or not correct?? I'm
thinking maybe something in the fuel line putting gas to the carb? But then
why is it more difficult once it's in the water?

Any troubleshooting suggestions is appreciated!