Merc 500 50 hp I need help

[Dirttracker]

I can get it running by taking the fast idle timing advance cable loose and working it and working the throttle plate on the advance to open the carb butterflies. I am under the impression that it should idle without opening the butterflies. It also require a lot of timing 20 to 24 deg. to stay running. I try doing the sync procedure but things don't seem to working out. The compression is good top dead center (TDC) is correct, the distr. timing I have move a single tooth each way but can't get just right. The serial # is 4283897 with the thunderbolt ign. I just rebuilt the carbs and have the mixture screw out 1 turn. oh by the way it was running good until it backfired, then it would start back but you couldn't put it in gear and accelarate

 

[Dirttracker]

Re: Merc 500 50 hp I need help

One other thing I done when I rebuilt the carbs. I put removable lock tite on the main nozzle plug, main jet plug ,idle screw and the channel plug. I didn't put it on the idle mixture screw

 

[Dirttracker]

Re: Merc 500 50 hp I need help

How do I sync this engine. It will run in gear but you can't give it any throttle or it dies?

 

[Ptolmy]

Re: Merc 500 50 hp I need help

I had a similar problem on that engine. Turned out the timing belt had slipped.
If you take off the cover over the timing belt, you'll see a small indicator on the pulley and another one on the flywheel. Turn the flywheel by hand and make sure that these 2 indicators line up together. Worth a shot..

 

[Dirttracker]

Re: Merc 500 50 hp I need help

Ptolmy,
I have tried that and move it one tooth each way. I just can't get it to idle unless I put a lot of advance timing to it and open the butterflies on the carbs.

 

[denis leblanc]

Re: Merc 500 50 hp I need help

Hi, I have the same problem with my motor 1975 merc 50 h.p. if you find the problem let me know and I will do the same too. I have a frend mechanic who should help me soon.