71 Merc 500 starts then dies

[Leeworthy23]

Having a problem with the motor, its a 71 merc 500, it will start up when I choke it, run for a few seconds and then die out. wont start again unless I choke it. Then it will run again and then die out.

I just changed out the fuel pump diaphragm today. Still having the problem so I put in a new gas tank and line with bulb, still having the problem. Any suggestions? Sounds and runs great when it runs for the few seconds.

 

[usskydvr]

Re: 71 Merc 500 starts then dies

Sounds like you may need carbs rebuilt, or perhaps just adjustment of the idle screws. Try setting the idle screws at two 1/2 turns out from lightly seated all the way in position. Then try adjusting 1/8 turn in at a time until you get good idle and a no stumble start when going from idle to full throttle.