help with 1981 mercury outboard 70hp

[charliesal7]

Hi, I bought a boat with a 1981 mercury 70hp 3 cylinder. It runs but stalls very often when shifting into gear and stalls out often when idling. Sounds like it is not properly getting fuel and I am wondering if the carbs need to get cleaned out? Does anybody know of any resources I could use to guide me through this? Is there something else I should consider that might be wrong with it?

Thanks!!!

 

[DavidMoore]

No Title

What makes you think it's not getting fuel?
1st check and adjust the idle speed, this is done in the water with engine in fwd gear. Should be about 700 rpm could even go a little higher if you can still smoothly shift.

Suggest to get the manual, but this link will get you started.

http://boatinfo.no/lib/mercury/manuals/70-75-80-90-100-115.html#/122

 

[charliesal7]

Thanks for your help!!!

 

[CharlieB]

It is likely that the carbs are getting dirty and it is time to be cleaned. The idle passages are small and a little dirt will restrict fuel flow and cause many idle problems.

You will want to turn the idle mixture screws in GENTLY until lightly seated. Count the turns in carefully as once finished with cleaning you will want to be able to return these to the EXACT same number of turns out again from lightly seated.

 

[charliesal7]

Sorry, this is a dumb question, but what do you mean by "seated?"

 

[DavidMoore]

Means, whilst counting the amount of turns carefully screw each the idle mixture screw until it just stops turning, this will an obvious point and is the point when needle hits its seat (or is seated), go no further you are not tightening anything just finding where the closed position is and maybe clearing some build up of grime. Then back them off the same amount of turns as you screwed them in.

The counting procedure above assumes the idle mixtures were set correctly to start with, which they might or might not be. The alternative is to back them to the initial adjustment setting = 1 1/4 turns then do the fine tuning as described in the link I sent (page 105) . This is a procedure that takes time and patience.