1988 70 hp johnson vro someone please advise

hi ,
i just bought a 15 ft mako with a 1988 70 hp johnson the vro unit has been disabled and iam running 50 :1. took the boat out for the first time it ran great. the second time i took it out the engine cut back on its own to idle when i was running wot. would not run faster than an idle all the way home. i got new gas and conditioner changed plugs and put a new fuel filter on it. the engine did the same thing again. i hooked up the muffs at home and started the engine ,i gave each cylinder a tiny shot of carb cleaner. i know im not supposed to do that but i did anyway. starting from the top carb it bogged so did the second but the third when shot rpms increased . i shut it down and got some seafoam to put in the gas to clean the carbs through the jets. am i wasting my time or do you think the bottom cylinder is dead.and what should i do, iam not a mechanic. any help would be appreciated
thanks
douglasb

Re: 1988 70 hp johnson vro someone please advise

I think you're on the right track. The bottom carb seems to be not delivering fuel which means it's not delivering oil. Obviously the thing to do would be remove the carbs and clean them. If one is plugged, the rest aren't that far behind.

Running carb cleaner in the gas to clean them may work but keep in mind what you're risking.

Re: 1988 70 hp johnson vro someone please advise

seafoam, keeps a clean carb clean, but does not clean dirty carbs. get the carb kits and clean, soak them and rebuild.

Re: 1988 70 hp johnson vro someone please advise

thanks guys ,
i hope thats all it is , i should get the rebuild kits for the carbs and se if that solves the problem. maybe i should do the bottom one first since that seems to be where the problem is coming from.
thanks
douglasb

Re: 1988 70 hp johnson vro someone please advise

Do the carbs. Remove the jets and physically run a soft copper wire through the passages while the carb cleaner is soaking. Don't short cut and make your self do it twice. Do them all, balance is important in a two stroke engine. If you have any doubt, pull the plugs and do a compression test too.

Re: 1988 70 hp johnson vro someone please advise

I'm all for a compression test.

Re: 1988 70 hp johnson vro someone please advise

i'm all for a compression test first, it's free, if you have or can borrow a tester. then all the carbs, http://forums.iboats.com/showthread.php?t=244013