Home › Forum › Ask A Member › 1978 Johnson 75 hp Stinger stalls when throttled up › Re: 1978 Johnson 75 hp Stinger stalls when throttled up
OK, well the best place to start is with checking sync/link. If one of those throttle butterflies is opened, even just slightly, the engine will behave this way. Make sure the throttle roller is not touching the cam at idle. Do you have a manual with the sync/link procedures? Have you done a compression test? These engines don’t do the usual OMC sneeze/cough thing when lean, they just kinda fade out and stall.
Have you done a spark test/replaced plugs? These engines will idle pretty well in neutral on two cylinders, but will die quick under load. Checked fuel filter/restrictions/air leaks/fuel quality/water? Having an assistant pump the fuel bulb might while the engine is running might help pinpoint pump problems/air leaks/restrictions as well.
PS- The 15" prop seems right for that rig, is it a cupped prop? Did you remove and physically clean the low and high speed jets on the carbs when you cleaned them? Were the carbs dirty, or did everything seem relatively clean? Is it possible that one float is stuck closed starving a cylinder? Remove the top bowl drain plug and pump the fuel bulb to make sure fuel is flowing into the carb, repeat with the other two carbs.