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1987 Evinrude 40 E40TLCUD Lack of power/acceleration

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brewmoody

New member
Recently purchased this boat a month ago and having problems with the engine. Seems like a miss, stutter and lack of power from high idle accelerating to planing speed. Starts instantly, idles fine and planing speeds are fine. So far I've emptied and cleaned the fuel tank and filled with fresh fuel, installed a new water-separating fuel filter, replaced all fuel hoses and primer bulb, thoroughly cleaned and rebuilt the carbs (note that the high speed orifice in both carbs were stripped and could not be removed for cleaning, but I did flush thoroughly with aerosol carb cleaner and blew out with compressed air), replaced and gapped (.040) spark plugs, adjusted sync and linkage, adjusted idle timing, removed a non-functional VRO pump and installed a new block-mounted fuel pump. Both coils test within spec, cylinder pressure is 144 and 145 and reed valves checked out okay. I'm by no means an outboard mechanic and am checking in here before taking it to a shop. Any ideas on what my problem is? Thanks in advance.
 
How did you adjust idle timing ?------Put a timing light on each lead and take it to full throttle on the lake.-----Observe the flashing light and compare how upper and lower cylinder spark behave.
 
racerone said:
How did you adjust idle timing ?------Put a timing light on each lead and take it to full throttle on the lake.-----Observe the flashing light and compare how upper and lower cylinder spark behave.
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I adjusted idle timing to 3 degrees BTDC. am on the water now but the timing light is at home. I'll grab it and try your suggestion. Thanks for the quick response!
 
Actually the idle timing looks after itself.-----Idle timing is a much confused thing on these 2 stroke engines.-----Maximum timing advance is set at the factory for the life of the motor.------Idle timing is the point where throttle plates open.----How did you check where throttle plates open ?
 
I adjusted per the OMC service manual page 1-40. I adjusted the cam follower to align with the lower embossed mark on the throttle cam at idle and in the center of the embossed marks when the point the throttle plates begin to open
 
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