Picked up a 1975 johnson 70hp sea horse, runs great wide open. Runs great on muffs, but the thing wont idle on water, in gear or in Neutral. Carbs have all been gone through. Any other thoughts? Will run around 4.5mph anything slower will die. Has to have the high idle lever up and bump the choke to start. Thanks.
While all internal combustion engines only need three things to run, fuel air mixture, compression, and ignition (spark) getting them to happen in the correct order at the exact correct time, and in the proper amounts can be a trying process. If the carb has been rebuilt, and the plug wiring is repaired I would start to suspect vacuum issues, could be air is getting in between the carb and manifold allowing for too lean a mixture at idle. May try getting her to run at whatever RPM she will run at and squirt a little carb cleaner around the carb base and see if her RPMs change. Good Luck, I know it can be frustrating.
My old 60hp did that mixed up a gallon of gas added a whole bottle of carb and injector cleaner. Mixed it all up ran the fuel line into jug and put the muffs on and ran the engine at fast idle. Do not run over cement you are going to get a lot of black carbon sludge coming out. The engine is fine the exhaust is carboned up by running the cleaner it will clean it all out. And it might drip for a day or more. I added a it to every other tank full after and it runs great since.
Whats the correct way to turn up the idle? Is it on the cable itself? I turned it up using the big screw that pushes on the lever on the motor, idles great in nuetral now but im gear under 4mph it still wants to die.
Whats the correct way to turn up the idle? Is it on the cable itself? I turned it up using the big screw that pushes on the lever on the motor, idles great in nuetral now but im gear under 4mph it still wants to die.
That would make life difficult.
Sometimes those idle mixture screws are down inside a tube, it would look like a small raised boss on the carb body…. maybe??
Not as much as i was hoping lol. Pulled the jets and all 3 carbs were crysta clear on the jet end of things anyway. Kinda wonder if they need a little fine tuning on the synch and link side. Above my paygrade lol. It idles in nuetral and i dont do much trolling anyway.
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