1979 Merc 120 I/O Hard starting problem

[The Hack Shack]

I have a 1979 Merc 120 4 cyllindar. It cranks well and has good compression across the board. Good spark. Last seasons fuel (with stabilizer).

It is a pain to start. In that I mean I have to pump the throttle a bunch of times, mess with the choke and vary the throttle to get it to start. Once started, it purrs like a kitten. I can let it idle for 45 min or more. I shut it off and I can wait one minuet or 5 min or a day, doesn't matter. Always starts up hard no matter how cold or hot the motor gets.

I read the stickey at the top of the forum relating to fuel system but I do not think it applies.
Any suggestions ? ? ? ? ? ? ? ? ? Thanks

 

[P 0 P E Y E]

Re: 1979 Merc 120 I/O Hard starting problem

How does it run under load?

If it performs good and turns up 4200 rpm plus or minus you may want to check your engine timing, distributer advance, and choke for proper operation.

Check for vacuum leaks.

When Did the engine last get a tune?

Hope this helps. Good luck.

 

[The Hack Shack]

Re: 1979 Merc 120 I/O Hard starting problem

Have not had it in water yet. Don't trust it enough for lake st. Clair. Bought it very cheap last fall and have no idea about tune up. Does the choke need to apply on a hot start? It runs up to a good rpm without issues.

 

[Don S]

Re: 1979 Merc 120 I/O Hard starting problem

Could be as simple as a faulty accelerator pump. When you operate the throttel, do you get 2 nice sprays of fuel from the accelerator pump jets, or just a little dribble?
PS: the carb has to be full of fuel for the accelerator pump to work.

 

[The Hack Shack]

Re: 1979 Merc 120 I/O Hard starting problem

I will check that over tomorrow. I will let you know. Thanks