86 Crestliner / 86 90hp merc sucking air

[brentsid]

I have a 1986 Crestliner 1650 fish and ski with 1986 inline 6 mercury 90 hp. Motor runs great, tunes up with new carb. Problem is it sucks air from somewhere and is very hard to start. I replace the fuel lines to carb and gas tank, replace gas tank fuel level sending unit and short fuel line to motor at the back of the boat. I can watch when I try to prime that the fuel flows right back down out of the filter, and I can hear air sucking around where the short fuel line goes in but I 'think' that line is tight. Could be on the motor side of the line connection? when it does finally run. My suspicion is the fuel pump? But looking for advice from anyone experienced with these boats. Considering replacing the fuel tank also for a tank in the back somewhere. Mine is 16 gallon under the floor.

Thanks!!

 

[Scott Danforth]

the two check valves in the priming bulb should prevent fuel from running back down. if they are not working, start with a new hose.

also, you should be able to pump the priming bulb until it is rock hard. if you cant, then you need to look at the carbs and fuel system on the motor.

if you hear a "sucking sound", my guess is that something is loose, or you have a fuel leak somewhere.