I have an older carbureted johnson 135 and when I took it out today it took off and did good for the first 1/2 mile or so but then started surging at full throttle but would do fine if backed off to about 3/4 throttle. The surging kept on but then the motor wouldn’t do anything. I would crank it up with the fast idle on and it would fast idle for a little bit and then die out. We tried to pump the priming bulb and it didn’t seem to help much. Any ideas as to what could be causing this?
sundance 1900
Turned out it is an ignition issue. Have a family friend mechanic here in the upstate and he told me to do a cylinder drop test and the rpms are suppose to drop the same amount when each spark plug lead is pulled and when the engine was part way warm it had intermittent spark and once it warmed up it will only run on the number 1 cylinder. He told me to bring it to him and he would do some test to figure out exactly what is causing it and he is going to fix it for me. Thanks for the help!
sundance 1900