Yesterday when fishing with my buddy on the Columbia river, his 45 HP Mercury caused us quite a bit of grief... The past few times that we have used it, when leaving the harbor, the engine would not go above 3,000 - 3,500 RPM at WOT for about 15 minutes, then all of a sudden it would take off and work fine for the rest of the day at WOT (5,500 or so RPM). When it wouldn't take off immediately, we checked the fuel tank vent (it was open) and the primer bulb (firm)... THEN.... yesterday, when returning to port at WOT the engine suddenly slowed down to 3,000 RPM and then started to die but didn't.. and maintened 2,500 RPM for a few minutes then died.. We got it restarted, and upon feeling the primer bulb, it was empty and had a pulsating feeling to it... the only way we could keep the engine running at idle (slow boat speed in the channel) was to pump the primer bulb several time every minute or so. This way the engine kept going.. My first thought was that there was an air leak somewhere in the older / brittle fuel line or a connection (o'ring) at the tank or engine was shot / gone.. I recommended that he replace the entire fuel line assy including tank / engine connectors and priming bulb.. check engine fuel filter.. but am uncertain if there is a fuel pump diaphram on the engine... Does this appear that we are on the right track or are we overlooking something obvious before we head off to West marine to get fuel linne components... One other thing... while trolling with the 6 HP mercury.. it would troll fine for about 5 minutes when it would also start to die, but then recover and run fine for another 5 minutes or so and repeat the die / run process.. (possibly related to the other problem mentioned above) as they run off the same tank fuel line after being split at a t-fitting just before each engines primer bulb... I am a Honda man and know very little about Mercury's.. Just trying to help and don't like the possibility of no power while fishing on the Mighty Columbia.... Opinions / thoughts please..
