Iowa Gator
New member
I have recently experienced a a strange problem with a 1976 6 hp Evinrude and I would like to share it with you in case you run into it. I picked up this very very clean ob from a dealer, it didn't have a prop or fuel pump, no big deal , go it home and it had all new ignition including new spark plug wires, carb rebuilt, and the water pump like new, I replaced the fuel pump and prop and stuck the motor in the test tank, it started well and idled pretty well then I opened it up and it would fall on it's face at mid range acting like a cylinder missfire. Back in the shop I checked the points settings and tested coils and conders and ck'd timing and carb sync, everybody was happy, retest, I am not happy! same problem, falls on its face at mid range throttle, put a spark tester on each cylinder and has great spark even when missfiring . Pulled the carb ck'd float level jet size (marked 44 ) checked the jet with numbered drill 57=0.043 (very close to .044 seems ok, retest, same crap 
. removed power head and cked exhaust plates etc like new inside including pistons and cylinders retest same thing. I eventually pinched the fuel line coming from the pump to the carb to shut off fuel to carb and at wot, with a terrible miss going on, as it ran out of fuel it cleared up and ran great for just a short time. I replaced the carb from another 1976 Johnson (jet marked 52) and it ran great. I,m still not sure what was happening here but it was deffinatly a carb failure, just thought I would share.
. removed power head and cked exhaust plates etc like new inside including pistons and cylinders retest same thing. I eventually pinched the fuel line coming from the pump to the carb to shut off fuel to carb and at wot, with a terrible miss going on, as it ran out of fuel it cleared up and ran great for just a short time. I replaced the carb from another 1976 Johnson (jet marked 52) and it ran great. I,m still not sure what was happening here but it was deffinatly a carb failure, just thought I would share.