Starts right up sometimes, but other times crank no start

[JeepGuy319]

Hi everyone,
I am new to boats and 2 stroke motors, but I do have mechanical experience working on cars and small engines. Anyway, I have a 1984 StarCraft with the 70 horsepower Evinrude 2-stroke. When I start it, I push the key in to activate the primer solenoid, and it seems to work sometimes, but half the time, it will crank forever until the battery drains. It cranks fast enough, and it runs great when it is warm. I am not sure what to do or where to start. It is a recent purchase, so I ran it last season but have not replaced any fuel or ignition system components yet. Does anyone know what could be causing this issue? The bulb on the fuel hose does not hold as much pressure as I think it should.

 

[racerone]

Do you hold the key pressed in while cranking it over ?--Have you tested operation of the electric primer valve ?-----The bulb is a manual fuel pump.----Only used to fill carburetors.----Once motor has been cranked or run , the bulb does NOT need to be hard.-----Start with posting the actual compression values.----Load test the battery.-----Does spark jump a gap of 3/8" on each lead ?----Take starter apart for inspection / cleaning / ohm check on armature and perhaps new brushes.