1979 Merc 7.5 cold idle problem

[BubbaBaxter]

I have just rebuilt a 7.5 merc. New rings, new gasket set, reeds are fine, rebuilt carb, rebuilt gear case ... rebuilt everything. I have sinc & linked it according to a Merc service manual, and have checked and re-checked my torque specs. No apparent leaks in the crankcase.<br /><br />The only thing I can think of I haven't done (yet), is to pop the welch plugs.<br /><br />It exhibits lean\pop like symptoms at idle for about 5 minutes. After that, it settles down to a nice idle (about 750 to 800 rpm).<br /><br />Any suggestions would help my sudden hair loss .<br /><br />As an aside, when I crack the throttle to WOT, it hesites at about 2500 rpm for a couple of seconds before winding up to top end

 

[Chinewalker]

Re: 1979 Merc 7.5 cold idle problem

Sounds like you need to richen up the low speed circuit a hair. .. If that doesn't do it, there may be a blockage in the carb causing it to run lean...<br />- Scott

 

[BubbaBaxter]

Re: 1979 Merc 7.5 cold idle problem

Thanks for suggesttion Scott, but I have already tried the lean drop method. I have pulled the carb apart (more than once) and made sure my passages were clean, float level & drop are correct and main jet and nozzle unrestricted. But ... no joy in mudville. I have even had a merc tech check out my settings, and he is just as perplexed.<br /><br />It must be one of those "once in a blue moon" scenarios. I'm just hoping that someone has visited that moon .