I have a 1991 Johnson 48 SPL J48ESLEIM, it is a new to me motor. It starts up easily, idles smooth and sounds great. I took it out for the first time started it up and let it warm up for about ten minutes and eased away from the boat ramp. When I tried to go to full throttle it didn't seem to power up all the way. I do not have a tach on it yet, waiting on a tiny tach to come in. Sitting in the middle of the lake, I put it back in neutral, and used the high idle and the motor reved up real high. I have the type of control to where you pull out the lever and move it forward to increase the idle. I put it back in gear and it still does not seem to rev as high in gear as it does in neutral. Using a GPS the highest speed I got was 5mph. I drove the boat around for an hour or so at different levels of throttle hoping it would clear something out but it never got better.
I don't know if the linkages need to be adjusted or if something else needs to be done. There does seem to be excess travel in the throttle control. When shifting from neutral to forward, I barely have to move the lever. After it engages forward I have to move the lever more than half way before it starts to power up. The range of lever movement from when it starts to rev up to when the lever bottoms out does not seem to be very much. I did a spark test and both jump a 1/2 gap, the compression on the top cylinder is 130 and the bottom is 125.
Any suggestions as to where I need to start?
I don't know if the linkages need to be adjusted or if something else needs to be done. There does seem to be excess travel in the throttle control. When shifting from neutral to forward, I barely have to move the lever. After it engages forward I have to move the lever more than half way before it starts to power up. The range of lever movement from when it starts to rev up to when the lever bottoms out does not seem to be very much. I did a spark test and both jump a 1/2 gap, the compression on the top cylinder is 130 and the bottom is 125.
Any suggestions as to where I need to start?