1974 Johnson 115 HP Will Not Idle

I have a 1994 Johnson 115 HP that wants to die during idle.

Last time out I ran the majority of the time at 3,000 rpm or less while sking and tubing. But after about an hour of running, I had to raise the cold start lever in order to get the engine to run. Then when I would lower the cold start lever to shift into gear the engine would die.

I did find a small amount of fishing line around the prop shaft and removed it and installed new plugs. Compression is good.

I have since adjusted the throttle cable at the engine to increase the idle speed, which made it easy to start the engine. But even with the idle speed set as high as 1500 rpm, the engine would start fine, then slowly loose rpm until at about 500 rpm it dies.

Any ideas or suggestions? Thanks!

Re: 1974 Johnson 115 HP Will Not Idle

Is it 1974 or 1994?

Have you checked your water separating fuel filter?

Throttle plates closed at idle and horizontal at WOT?

Spark OK at cruising speed?

Re: 1974 Johnson 115 HP Will Not Idle

ezeke, thank you for your replay:

It is a 1974 (36 yrs old)

It doesn't have a water seperation filter

Throttle Plates (butterflys) don't appear to totally close at idle. They do open completely to horizontal position

Motor runs fine wide open - 5,000 RPM and pushes boat at about 45 MPH.

Re: 1974 Johnson 115 HP Will Not Idle

When the control is in neutral with the warm-up lever down, the throttle plates should be fully closed. You adjust and synchronize the carburetors first, then the roller to the cam follower, then the cable.