88 mariner 75 fouling plugs

dozerdoodle

Cadet
Joined
May 19, 2009
Messages
15
help completely frustrated, have a 1988 75 mariner 3cyl. when it's running on three makes plenty of power, 37-40 mph. problem is when i run it low speed in no wakes areas. it seems to load up, run a little rough and will eventually stop firing on one or more cylinders, i can usually catch it and blow it out but twice this season i have lost plugs to this condition, here's what i've done so far. compression is 120 in all three, and that was before i did a dunk method decarb, changed from wallmart to quicksilver oil, new ignition wires, tore down and cleaned carbs. verified needle valves sealing and checked float height, checked resistance on coils and triggers, checked fuel pump and enricher to make sure raw fuel isn't getting sucked in, also made sure marks line up on injection pump linkage. i was also thinking water in fuel, i do keep tanks outside but only leave vent cracked for expansion when sitting and i put dri gas in every time i fill up. what am i missing, i swear this thing is getting too much oil but can't see how, maybe i should premix some gas and see if it runs better without the injection hooked up. by the way when this happens i usually have two wet looking plugs, insulators are brown but not black, and it's not allways the same cylinders that go out? i know there are smarter people than me out there and i need your help. addl info. i have replaced the thermostat earlier this season, thought i might add this since i have read a engine runnig too cool is prone to fouling, thanks in advance
 

dozerdoodle

Cadet
Joined
May 19, 2009
Messages
15
Re: 88 mariner 75 fouling plugs

finally took pig to repair shop seems all my trouble was from a faulty switch box "cdi" running good now
 
Top