mercury 25hp idling issue

[mdp23]

I have a 1995 mercury 25 2 stroke serial # og232616. I have fire on both cylinders but some times it runs smooth and other times it will just die. On starting everytime it will idle different. One time when choked it will idle fast but not idle down then the next time it will idle slow then die. Could this be the switch box or something else.

Thanks

 

[Texasmark]

Re: mercury 25hp idling issue

Varnished carbs and/or old-bad gas are the first things to come to mind. Put in a carb kit and get a tank full of fresh gas/oil mix (if no VRO and probably doesn't have one) and try again.

 

[mdp23]

Re: mercury 25hp idling issue

carb has just been cleaned and new kit installed less than 30 days ago and I have not ran any ethanol gas through it. I use quick silver oil and marine stabile every time

 

[will941s]

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.

 

[mdp23]

Re: mercury 25hp idling issue

I'll check will check the carb again but I have not ran any ethanol added gas to it we have 2 gas stations here that does not sell the ethanol gas