1972 50 hp Cranks, but on runs on one cylinder

[michaelcauley43]

Hello, I am new to the forum. I tried to search my question, but I did not find anything quite like I was looking for. I traded for a 1972 50 HP Johnson (50ESL72C) and twin parts motor about 2 weeks ago. I have been tinkering with it, but not sure if I have the problem diagnosed correctly or not. It cranks very good, but then only runs on 1 cylinder (sometimes will pick up and run on both briefly). I have spark on both plugs, however when I cranked it I notice a little bit of gas coming from the top carburetor. I cleaned it and the gas stopped coming from the front of the carb, but still only running on 1 cylinder. I replaced the rectifier with a new one. I changed the plugs, ran the same. I changed the power pack, motor wouldn't start. Went back to the other power pack, disconnected the temp sensor wire, ran the same. I disconnected the diode wires and the motor seems to be running better, but I only got to run it for a second before I had to stop.

Can the diode be causing this problem? Do I have a bad diode or should I continue checking?

I am a novice at working on outboards at best. My dad is pretty good, but says himself he runs into trouble with the wiring. I have the test list I have am working through; obviously I got to the diode test and stopped. Any help would be greatly appreciated! Thank you in advance!

[boats.net]

Use a timing light to see if loosing fire to any cylinder. Run a compression test.

[michaelcauley43]

I have checked the compression, 150 on each cylinder. I will look up the timing light test and give it a try. Thank you!

[michaelcauley43]

Ok, so I went to crank crank the motor today, it fired up first key turn, but it ran on 1 cylinder again. So the diode is not my issue. When I tried to start it again, it was very hard to start. I did eventually get it started again and it ran as long as I wanted it to, but still only on 1 cylinder. The last time I tried to start it, it would not start. It would just fire and sputter a few times then shut down. I checked the two orange wires at the power pack, motor not running, but I was getting 950 ohms. So this means a bad power pack since the tolerance is 450-600? Or is the test even good since the motor wasn't running? That's the only update I have for today. I great appreciate any help!