It's good to be back in the game.

My 1977 Mercury Merc 700 70hp 3-cyl was hesitating, rough idle, difficult to start, sometimes carb floats would stick causing it to not start, and eventually it wouldn't go into high speed, then it would just die any time it was put into gear.

I decided it was time to rebuild the carburetors and fully test and troubleshoot the motor.

This was my first time to tackle a job like this. I had already serviced the lower unit, changed the spark plugs, replaced the water pump and impeller, and rebuilt the fuel pump, so armed with my service manual, TFF, YouTube, and Startpage (private google), I set out to tackle this myself.

I ordered the kits and rebuilt the carburetors to spec successfully. After i reinstalled them, the engine definitely started easier and the carbs sounded good, but it still wouldn't run right. Time to dig deeper.

Following good engine troubleshooting methodology my first step was a compression and spark test to be sure the power head was good and the engine was worth repairing. The compression test results shocked me. All 3 cylinders measured 119 PSI. There was no variation. Amazing. I couldn't believe it so I did the compression tests multiple times with the same results. The Powerhead is awesome and this motor is definitely worth fixing. I performed the spark test while checking compression and discovered no spark on cylinder #2. At this point I knew I needed to dive deeper into the Ignition System.

I figured I may have some ignition issues as I could see some corroded wires coming from the Stator. I took photos and drew diagrams of all of the wiring and proceeded to disconnect all of the ignition system wiring so I could test every circuit of each component. I noted that while disconnecting all of the wires some of the connections felt loose. I was immediately hopeful this was the only problem. I continued my process so that I could verify the functionality of all of the components. The Trigger, Rectifier, Switch Box, and Ignition Coils all tested good with all readings in the middle of the spec range. The Stator tested good with the exception of the charging lines that go to the rectifier for charging the battery and running the tach. Since that was the case I knew it would still run the engine, it just wouldn't charge the battery and operate the tach. Once these tests were complete, I was getting even more excited that a loose connection may be the only real problem. After reconnecting everything I did another spark test. This time I got a beautiful bright blue spark on all 3 cylinders. I was so excited I could barely get the spark plugs back in.

I test fired the engine in the driveway with the flush muffs and it fired right up and sounded great. Even though it was already late I had to head to the water to test it out. I gathered the wife and kid and we headed out to the water. At the dock I checked that it would go into gear without dying (which it did) and we departed for open water. Once outside of the no wake buoys I increased the throttle, and it smoothly accelerated all the way to WOT. WOOHOO!!!

The next day we went back out to run it some more. It has that nice deep gurgle that a good running outboard should have. Overall it is fixed and runs better than it has. I have a little idle mixture tweaking to do at the carbs to really smooth it out, and I'll replace the Stator soon so it can charge my batteries and run the Tach. Once the Stator is replaced I can do a full Link and Sync to ensure peak performance.

...but for now, the main thing is we're back on the water.

Last night the Wife and I went fishing, and I noticed I wasn't focused on presentation or technique because I was just so excited to be there.

I had to share my triumph.
Thanks for reading.