1996 Johnson 115 HP Rough Idle & Misses

[jv4studio]

Hello, I have a 96 Johnson 115HP that idles roughly for a few seconds and then dies. I can't put it in gear or it will die unless I gun it a bit. Once I get it above idle it runs good, but I hear it miss every few seconds. At WOT the miss is very noticable. With two adults and gear the boat takes about 15 to 20 seconds to get on step and tops out at about 33 mph. I am going to rebuild the carburetors to try and cure this problem, but I wanted to see if anyone has a different thought or if I need to more than just rebuild the carbs.

 

[Captain Jeff]

Re: 1996 Johnson 115 HP Rough Idle & Misses

A true miss is an ignition problem, not a carb / fuel problem. It may be a good idea to rebuild the carbs but you may want to hook up a timing light to each of the spark plug wires and see if it flickers erratically when you are having the misses. If it doesn't then most likely you have a fuel / carb problem which it very well could be. Do you have the VRO system? Which way is the red lever pointed? There are a bunch of things that can cause this problem and you may want to try to rule some out before spending time and money.

 

[jv4studio]

Re: 1996 Johnson 115 HP Rough Idle & Misses

I don't believe I have the VRO system, since I've never seen that anywhere on my motor or cover. Also, I believe that the red lever is in the forward postion. I should add that after I run the engine at WOT for a few minutes the miss goes away, but it still idles poorly and then dies.

BTW, thanks for showing intersting in this and I appreciate any and all advice.

 

[ezeke]

Re: 1996 Johnson 115 HP Rough Idle & Misses

Most 1996 V4 Engines have QuikStart, a part of the ignition sytem operated by the powerpack. QuikStart automatically advances the timing by 10º when the motor is started and keeps it advanced until the engine reaches a temperature of 96º F and/or RPM of 1100.

If the fuel supply is normal, and QuikStart is functioning, starting is usually easy, and the engine will warm to 96º.

If you attempt to accelerate the engine during this process, Quikstart is dasabled at 1100 RPM and the engine should idle less smoothly until it warms up.

If QuikStart stays on all of the time, it can be from a bad powerpack, a bad starter solenoid, a bad port temperature switch, wiring problems, etc.

 

[jv4studio]

Re: 1996 Johnson 115 HP Rough Idle & Misses

What is the red lever for on the right side of the engine (if you are facing the engine)? Also, after the engine is warm and Quickstart is disabled, the engine still idles very rough and will die after a few seconds. Is this electrical too or is it fuel related?

 

[ezeke]

Re: 1996 Johnson 115 HP Rough Idle & Misses

The small red lever on a cylindrical device is a switch which allows you to manually pump fuel directly to the engine in case of a battery failure.

In normal operation the red switch has to be aligned with the cylindrical solenoid or the engine will flood. In that alignment you pump fuel to the engine by pushing in the key for a cold start.