--------------------------------------------------------------------------------<br />I own a 1969 (I believe) 4.0 HP Merc outboard...SN: 2498980. Tried to get it running this year and encountered start-up trouble. I thought initially it was varnish but that does not seem to be the case--here is where I'm at:<br />The engine will start first pull PROVIDED I prime the heck out of it to the point that I get gas oozing from the float bowl. It will run fine until it starves out or unless I sit there and press the bulb. The bulb seems to hold the prime, the lines are clear, the tank (remote) vent is open--all filters (tank and fuel) are clean. I see no evidence of varnish anywhere. I cleaned the sediment out of the float bowl, checked the float and needle--no apparent problems. My guess is a bad fuel pump diaphragm but I do not know whatI am looking for to verify that. I see no cracks or holes but beyond that it looks like a diaphragm. The rond section has a bit of play in it though--should it be drum tight? I do not want to buy a whole bunch of parts that I do not need. The fact that she starts up first pull (provided I get the bowl full of gas) tells me that the carb is fine. <br /><br />If it does not sound like the pump diaphragm then what else could it be?
