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76 mercury 115 inline six problems

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Oldboatguy8911

Contributing Member
I can crank the motor in advanced timing (warm up lever) but once I bring it down it dies, I have messed with the carbs a bit and when I rotate the flywheel with a spark plug tester at WOT it sparks at 21* ... What seems to be the problem? I have 120+ across all cylinders . I can get the motor to crank and idle in adv time but no go any other way.. Please help and I will answer all the questions I can, I haven't hit it with a timing light while cranked but will soon looking for further help tho.. Could it be the idle adjustment screw?
 
It may simply be idling too low.

Have you adjusted the carbs, motor warmed up, in gear, with the boat tied to a dock (or on a trailer)? That would eliminate mixture problems.

Jeff
 
The marine mech took the boat for a spin and he said he smelled old gas coming from the carbs n to take them off givem a good cleaning and go from there
 
also i was wondering if i could seafoam or spray some carb cleaner into the carbs and run some seafoam with some gas to clean them before dissassembling and taking them off? could i give that a shot?
 
I drain the carbs and fill them w/Seafoam via the fuel line and sqeeze primer. Left them soak 24-48 hrs...the longer the better on old motors.
 
So i have ran 4 gallons of fresh gas with seafoam in the motor and it seems to really be helping clean out those carbs. However i still have a planeing problem some of the time. When i crank the motor i can hear a noticeable differents in the idle almost as if it were not getting enough gas? I can tell when i am about to go to WOT if it is gonna plane out just by the engine noise. It sounds like a powerful growl. When i throw it into WOT i really take off and i get out on plane and hear the RPMS climb but as it hits top end i hear it rev down and run at a comfortable RPM but when it does this i lose speed. I know its a carb issue, but im curious when im in WOT why is it revving down almost as if i have backed the throttle down. Im sorry if im not descriptive enough on this subject and if you have any questions i can try to answer them. please feel free to ask questions, I am going to take these carbs off and rebuild them after i have eliminated all possible probs. could it be a stuck float?
 
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