Rough stall; coughs and sneezes at idle only

[bf2313]

My 1995 Johnson, 150hp, has an idle problem. When the engine is idling for approximately 3 minutes, to load and unload at the dock, you will hear a cough or sneeze every 3-4 seconds. Also during that time, it will stall 3 or 4 times. No visible fuel leaks, no variance in exhaust smoke, and motor runs great at all other throttle speeds. Don't know if this is related to the problem or not, but recently I noticed after being out on the water all day that I'm having a problem with starting it without squeezing the primer ball. Previously I would squeeze the primer ball prior to going out for the day, and didn't need to re-prime the motor when starting and stopping.

 

[basspirate]

Re: Rough stall; coughs and sneezes at idle only

i have a 1999 johnson 130 and found that the primer solenoid was placed in a really bad spot where sometimes when you steer it knocks the manual startup switch on the soleniod (little red knob) into the wrong position. the engine will run great except at idle where it will have a haunting idle (up and down) and will have misfires. check the position of the switch.

 

[bf2313]

Re: Rough stall; coughs and sneezes at idle only

I checked to make sure that the red arm is in the down position, and when I swing it to the up position it starts to flood, so I imagine it's working properly and in the correct position. I appreciate your reply, any other ideas?

 

[winfieldh]

Re: Rough stall; coughs and sneezes at idle only

This sounds similar to my 200hp johnson. Sneezes and coughs and fuel line looses prime after sitting for a while. I am not a mechanic, but have come to conclusion this is air getting into fuel system, somewhere....somehow. I have replaced clamps and hoses and that has helped, but it still does this occasionally. I will keep replacing/tightening. If that doesn't solve then possibly somewhere in fuel pump?

 

[jonesg]

Re: Rough stall; coughs and sneezes at idle only

My 1995 Johnson, 150hp, has an idle problem. When the engine is idling for approximately 3 minutes, to load and unload at the dock, you will hear a cough or sneeze every 3-4 seconds. Also during that time, it will stall 3 or 4 times. No visible fuel leaks, no variance in exhaust smoke, and motor runs great at all other throttle speeds. Don't know if this is related to the problem or not, but recently I noticed after being out on the water all day that I'm having a problem with starting it without squeezing the primer ball. Previously I would squeeze the primer ball prior to going out for the day, and didn't need to re-prime the motor when starting and stopping.

Remove the airbox and put 2 fingers in each carb to see if chokin ea carb allows you to trace it to an individual carb, the sneeze will stop if you find it.
Also try spraying some WD40 around ea carb gasket.
The darn spaghetti seals can leak , they're tricky to position unless greased up a bit to hold their position when installing the carb.

Try to orientate the bulb so the arrow points UP, it possibly has a leaky valve that allows fuel to syphon back to the tank when sitting.

 

[jonesg]

Re: Rough stall; coughs and sneezes at idle only

This sounds similar to my 200hp johnson. Sneezes and coughs and fuel line looses prime after sitting for a while. I am not a mechanic, but have come to conclusion this is air getting into fuel system, somewhere....somehow. I have replaced clamps and hoses and that has helped, but it still does this occasionally. I will keep replacing/tightening. If that doesn't solve then possibly somewhere in fuel pump?

See my post above . Its not the pump.

 

[bf2313]

Re: Rough stall; coughs and sneezes at idle only

Wow, that makes sense. I'm glad to know that the check valve is in the squeeze ball. It's old and a little dry rotted, so I'm going to go ahead and replace it. Thanks, jonesg!

 

[Ozerimar]

Re: Rough stall; coughs and sneezes at idle only

I know this post is a little old but did you find out why it was coughing and sneezing??