It looks like I have come to the right place.
I have a 5 year old 4hp 4 stroke mercury outboard
that worked fine until about six weeks ago, although in order to start it I had to have the throttle wide open. Once started it ran smooth and quiet.
Now, sometimes it starts on the first pull and runs great. The majority of the time, it will try to start on the first pull and on the 30th pull, but will not get beyond a sputter or sometimes a few seconds of very very low speed running, but then dies.
I have it hooked up to a new external tank with new fuel line, quick connect at motor
end and new bulb. Ethanol fuel with treatment. I also tried filling the internal tank with ethanol free fuel, but same problem.
The marina mechanic
told me it was because it was cold (Southern Virginia). I lived in New England
for 40 years and never had trouble starting my snow blower in much much colder weather
I spoke with a mercury mechanic
on the phone
who thought it might be a tear in the fuel pump diaphragm
or a problem with the carburetor. I know nothing about engines. I just cannot see how either of these problems fit what I am observing. Again, if I get it started, it runs great.