I've got a 1997 Johnson 115 fast strike (J115GLEUC) that starts and idles fine cold or hot but when you accelerate over half throttle it surges bad. You can back off the throttle and the surging stops and you can run like that with no problems as long as you wish but when you get past about 1\4 to 1\2 throttle the surging starts again and will not stop until you back off the throttle.
I've only owned the boat about 2 months now and it's been in the shop twice. I don't know the history of the boat only that it had been sitting a good while. The initial inspection found someone had removed the thermostats and there was a significant temp difference from one head to the other without them. I had the thermostats put back in and tried it again.
The boat ran strong after that with no surging or anything, for about 30 minutes til it began missing and eventually died and would not restart. After getting the boat back home and siting awhile, of course it started back up. I took it back to the mechanic and he said it was most likely the power pack failing when hot. I then replaced the power pack, coils, wires and optical sensor.
All the other issues I had are now gone and I ran the boat about 3 hours yesterday and then the surging started. At first I could open it wide open and it did ok, a slight bit of surge but it wasn't constant but after about 2 hours it started the surging with anything over 1\4 to half throttle. I put a new set of plugs in it on the water, even though the plugs looked fine and it didn't make any difference.
I've check the fuel tank vent and it is open. Pumping the fuel bulb while it is surging has no effect on it. The first thing I did when I got the boat was to pull the carbs and clean them. I even pulled them a second time just to satisfy my mind although everything was clear.
The boat still has the original oil pumped hooked up.
I'm just at a loss and really trying not to put it back in the shop a 3rd time.
The compression numbers ran the first time at 140,140,135, 130... the timing was set as well.
Any ideas?
I've only owned the boat about 2 months now and it's been in the shop twice. I don't know the history of the boat only that it had been sitting a good while. The initial inspection found someone had removed the thermostats and there was a significant temp difference from one head to the other without them. I had the thermostats put back in and tried it again.
The boat ran strong after that with no surging or anything, for about 30 minutes til it began missing and eventually died and would not restart. After getting the boat back home and siting awhile, of course it started back up. I took it back to the mechanic and he said it was most likely the power pack failing when hot. I then replaced the power pack, coils, wires and optical sensor.
All the other issues I had are now gone and I ran the boat about 3 hours yesterday and then the surging started. At first I could open it wide open and it did ok, a slight bit of surge but it wasn't constant but after about 2 hours it started the surging with anything over 1\4 to half throttle. I put a new set of plugs in it on the water, even though the plugs looked fine and it didn't make any difference.
I've check the fuel tank vent and it is open. Pumping the fuel bulb while it is surging has no effect on it. The first thing I did when I got the boat was to pull the carbs and clean them. I even pulled them a second time just to satisfy my mind although everything was clear.
The boat still has the original oil pumped hooked up.
I'm just at a loss and really trying not to put it back in the shop a 3rd time.
The compression numbers ran the first time at 140,140,135, 130... the timing was set as well.
Any ideas?