merc 500 with issues help please

[dickjackson]

1977 mercury 50 hp 4cyl rebuilt carbs and all fuel lines replaced, only had spark on 3cyl replaced switchbox great spark all 4, new stator in 2003 has set for 2 years. the motor runs great with the muffs in the driveway. in the water it will idle fine, when u give it WOT it acts like it wants to plain but it doesent and goes about 8 mph i have put a whole and time and money in this piece and i would like to fish this year. PLEASE HELP

 

[coolguy147]

Re: merc 500 with issues help please

check spark might not spark on a cylinder

 

[flatcat77]

Re: merc 500 with issues help please

throw a new set of plugs in it too. one might have fouled out. and after you run it pull them out and read your plugs. they should be a tannish brown bag color. and all 4 should be consistant. if not somthing may have gotten through your fuel system and its sitting in your carb until you give if WOT then its obstructing your flow thus causing a huge power loss. i'de check the plugs though first. that sounds line my 500 when its ready to get some new ones. sometimes if i run it for a few minutes it will clear out. but sometimes not. i always keep 4 new plugs in my boat box. you never know.