Re: mercury 25hp idling issue
I had kind of the same problem. Mine would start fine than all the sudden start racing, pop, and die or barley stay at idle...then race again. Cleaned and re-built the carb, new gas and a linc and sync. The carb was rough inside...had the innards of the fuel line stuck on the ports due to ethanol fuel, and the needle was sticking due to varnish. After that it would'nt run worth a crap so I had the linc and sync now runs like a top. Make sure you check the compression with it warm (mine was 125 all the way around) and have it tuned and you should be set. I've heard mixed reviews on this, but on all my OB's, when I'm done running them I unplug the gas line and let the engine use whats left in the carb. This rids the carb of the bad ethanol gas and since I've been doing this I've been getting twice the life out of a carb job. Have had no problem with loss or Compression or engine damage.