1984 merc 150 cough and pop

[dadgummit]

this engine is hard to start and keep going it will cough and sneeze then die. after several attempts it will finally smooth out and run. its worse when its cold and better when its hot. carbs are fresh and ive got a good prime. any ideas? thanks.

 

[jdupree]

Re: 1984 merc 150 cough and pop

When you say the carbs are "fresh" does that mean re-built? Unless I am mistaken, it sounds like you are not getting enough gas. If the carbs have been re-built, I would start tracing the fuel system.

 

[LubeDude]

Re: 1984 merc 150 cough and pop

I`m not saying that this is your problem, as this is usually the result of some kind of lean condition, but my Merc 150 did the same thing and it turned out to be the reeds.

What had happened is that the reed blocks {which are made of aluminum] had worn and wouldn`t let the reeds seal properly at low RPM.

 

[dadgummit]

Re: 1984 merc 150 cough and pop

the carbs have been rebuilt and with a good prime there should be plenty of gas. do i need new reeds and blocks? and how hard are they to change? they are right behind the carburetors aren't they?

 

[j442w30]

Re: 1984 merc 150 cough and pop

Right behind the carbs but inside the crankcase and that requires the powerhead to be disassembled. They're shouldn't be that hard to change.

 

[andy6374]

Re: 1984 merc 150 cough and pop

If you push the key to choke, will it help?

Are you sure the throttle plates in the carb throats are fully closed at idle?

Have you tried pumping the primer bulb once started?

What are you idle (not in gear) RPMs?

Have you checked compression and spark on all plugs?

Just trying to weed out problems here.

 

[dadgummit]

Re: 1984 merc 150 cough and pop

i will check all those things andy thanks.