35hp Johnson Acceleration Issues

[Lampos]

Hello everyone-

I have a 1977 35hp Johnson Seahorse motor. The motor has been great to me for the 2 years I have owned it. Recently it has developed a bit of a problem. When I first get the boat in the water and start it, it idles smoothly and when I hit it full throttle it jumps right up and goes. Here's the problem, if I slow down to around idle speed or 2-4 mph to watch the graph or troll, when I push the throttle back up the motor doesn't respond, just keeps idling. It will eventually make its way up to full speed, just takes 10, 15, sometimes even 60 seconds to get there. However, if I shut the motor off and fish for a bit when I fire the motor back up will go back to full throttle no problem. Only issue seems to be when I go to full throttle, slow down, then go back to full throttle again is when it fouls up. If the motor has been running a while it will also start to idle rough as well. I have already replaced primer bulb and fuel lines from tank to motor. Figured I would replace the spark plugs next. Any advice would be greatly appreciated!

Thanks,

Denver

 

[ksubigbuck]

Re: 35hp Johnson Acceleration Issues

Sounds like it is loading up with fuel at idle. I don't know anything about that particular motor, but I would try adjusting the carb's low speed needle.

 

[tashasdaddy]

Re: 35hp Johnson Acceleration Issues

have you check spark, when it is acting up? could be a coil heating up and failing, also could be crud in the carb.

 

[Lampos]

Re: 35hp Johnson Acceleration Issues

I'm a novice at all of this. Give me directions for how to check spark, or would changing the spark plugs fix this if that was the problem anyway? I figure they're due to be changed regardless.

Thanks,

Denver

 

[jasper60103]

Re: 35hp Johnson Acceleration Issues

I'm a newbie too. A spark test verifies the ignition, not your spark plugs. But changing your plugs every year is a good idea though. You can pickup a spark tester from auto parts store for under $10.

Spark Test Procedure

1) remove ALL the plugs.
2) ground out the plug wires (nail in the boot placed against the block works).
3) connect a plug wire to the tester and adjust the gap to 7/16". Clip the other end to the motor ground.
You may need a helper for the next step.
4) electric start: jump the starter solenoid from the power lead, or turn the ignition, and watch for spark.
rope start: pull the rope, and watch for spark.
5) The spark should jump the 7/16" gap with a crisp blue spark.

repeat for each plug wire.