Purchased this motor and, of course, was told it was running when pulled. Took a while to find controls for it but finally got it installed and it ran well until one day. After taking off, the motor bogged down and I could only run 5 -7 mph at 1/4 to WOT. Took it to the shop, the owner was known as the best mechanic around. He had it for 2 weeks then called and said it was done. Good compression but they changed sparkplugs, stator, impeller and rebuilt the carburetors. $600 later I put it on the water it started and Idled fine but when I throttled up the same thing happened. Called the shop and they sent one of the guys up to the lake to see what was going on. Same thing happened to him so we hauled it back to the shop. They kept it another 2 weeks and then called and said they had no idea what was going on and were giving up. I was leaving in two days on vacation to a distant lake so I ended up pulling it and buying another motor and it has set for a year. So now I'm over 1000 into it and it's still sitting in the barn. I'd like to get it out of the way and get part of my money back on it but I don't feel right about selling something that's not %100. Anyone else had these issues with this motor?
It sounds like your "mechanics" were not factory trained and employed by an Evinrude dealer. One thing easily overlooked is plugged passageways inside the carb. A spray can or cleaner or a quick soak will not always flush out dried up fuel deposits. Another cause could be a stuck or sticking timer base or a cylinder quitting firing when the throttle is advanced.
The old 70HP was one of the most reliable and rugged of all the engines produced by the former OMC.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.