so, i bought a boat that had a 1976 johnson seahorse 15hp that the owner said had been put up in running condition about 5 years ago. it cranked after several tries, and had a rough idle with a little smoke, but both cylinders tested at about 65, so i decided to give it a try...
...replaced both plugs, both coils and plug wires, new intake fuel line to the fuel pump, new fuel pump, rebuilt the carb (with the help of a pro), but did not replace the fuel line between the pumb and the carb. the carb was very clean prior to the new parts, suggesting that it was put up in good condition. when the pro reset the high speed needle, his test tank run was so good that he did not pull the flywheel for the points and condensers. the old gear oil was good, but i drained it and refilled anyway...
so, at the lake the motor cranked and idled well, and the water pump pushed a spray from the pee-hole. off we went and it ran very well at both low speed and high speed without smoke or unusual noise. after 15 minutes of alternating between low speed and high speed, i ran it at full throttle for about 15 minutes, at which time it lost power to about 25% for about 10 minutes until i made the dock and reduced the throttle, then it stalled and would not hold idle upon restart.
again, no smoke, noise, or warning of the loss of power, so i don't think it is a problem beyond fuel or ignition. i'm using new external tank and bulbed line with non-ethanol fuel. squeezing the bulb during the problem did not change the status. i wonder, since i didn't replace the fuel line from the pump to the carb, would that have allowed for something to dislodge and partially block an opening in the carb, or is something else amiss? any opinion is welcomed...
...replaced both plugs, both coils and plug wires, new intake fuel line to the fuel pump, new fuel pump, rebuilt the carb (with the help of a pro), but did not replace the fuel line between the pumb and the carb. the carb was very clean prior to the new parts, suggesting that it was put up in good condition. when the pro reset the high speed needle, his test tank run was so good that he did not pull the flywheel for the points and condensers. the old gear oil was good, but i drained it and refilled anyway...
so, at the lake the motor cranked and idled well, and the water pump pushed a spray from the pee-hole. off we went and it ran very well at both low speed and high speed without smoke or unusual noise. after 15 minutes of alternating between low speed and high speed, i ran it at full throttle for about 15 minutes, at which time it lost power to about 25% for about 10 minutes until i made the dock and reduced the throttle, then it stalled and would not hold idle upon restart.
again, no smoke, noise, or warning of the loss of power, so i don't think it is a problem beyond fuel or ignition. i'm using new external tank and bulbed line with non-ethanol fuel. squeezing the bulb during the problem did not change the status. i wonder, since i didn't replace the fuel line from the pump to the carb, would that have allowed for something to dislodge and partially block an opening in the carb, or is something else amiss? any opinion is welcomed...
