Bewitched 1984 75HP Merc.

In the middle of the season last summer, my buddies Merc wouldn't always fire up. At times we had to spray gas (pre mixed with oil) into the carbs and she fired right up and always restarted throughout the rest of the day. Some days she would start and some days she wouldn't. It was a 50/50 proposition. We took it to a local Merc dealer who charged him $95 to tell him that they couldn't find anything wrong with it. We used it throughout the Fall with the same problem. I'm sure it will do the same thing when we start using her this Spring. Everything that I checked out mechanically and electrically seemed OK. I gotta wonder why the Merc mechanic couldn't find anything. Do we go looking for another Merc guy?
Nightstalker

Re: Bewitched 1984 75HP Merc.

give me a serail number so i can see exactly which motor you have & i might be able to tell you a solution.rick

Re: Bewitched 1984 75HP Merc.

Sounds to me like you could use a good carb cleaning a rebuild and a fuel pump rebuild never hurts either

Re: Bewitched 1984 75HP Merc.

If you clean them yourself pay especial attention to the float levels and low speed pickup tubes.

Re: Bewitched 1984 75HP Merc.

I don't know if this is helpful on an 1984 or not, but I had a 1975 650 do the exact same thing. Turned out to be the switch box and the coil. It was a few years back, but the best we could figure was the coil had a crack in it and didn't test out well resistance wise and that eventually blew the box.

It was very intermittent and a real bugger to diagnose until it just finally blew completely.

The 3cyl 650 was a Type III ignition and I think everything after 76 to the late 80's was Type IV. I know they are similar, but there are difference and I wouldn't know how they relate exactly.