Merc 500 fuel problems

[Scoots]

I bought this motor last year and it ran so-so. Always started up great , but, bogged down most of the time going into gear. If I eased into the throttle it seemed to run better than punching it. I recently rebuilt the fuel pump and changed the gas lines and it ran great in the driveway ( no chance yet to get out on the water). Yesterday I cleaned and rebuilt the carbs and now it won't start. It turns over and appears to be getting fuel into the carbs , but, it just doesn't want to start( almost as though there is no suction). I set the idle at 1 1/2 turns out.
I would really appreciate any advice as to what I perhaps did wrong in re-building/reinstalling the carbs. By the way this is a 1971 Merc 500.

 

[coolguy147]

Re: Merc 500 fuel problems

what is the compression? spark on all four cylinders?

replaced the water impeller lately? gear oil?(just some other maitenance items)

try opening the carbs a 1/4 turn out from where they are right now.

you may have to readjust the idle after. if it does nothing try pumoing the primer bulb as you are accelerating?

 

[Scoots]

Re: Merc 500 fuel problems

Thanks for your reply. Spark is good on all four and I replaced the water impeller last year. I'm going go back and go thru things again(and again and again).

 

[TitanTea]

Re: Merc 500 fuel problems

Does the primer bulb become firm after several pumps? Are you using a MerControl controller?

 

[Scoots]

Re: Merc 500 fuel problems

Yes, the bulb firms up and I am using a mercontrol. After looking at it again I noticed that when the distributor turns (at wot ) the lever on the top carb that opens/closes the butterfly in the carb. is not making enough contact to open it up all the way. This leads me to think that something is wrong here. At idle with the throttle advance full forward, should the carb be open or closed??