rude misfiring and stalling at idle when hot.

[dcolpitts]

1986, 140 evinrude starts fine idles fine till warmed up, after 5-10 minutes at 800rpm in gear it wants to start to misfire( spit) for anothe 5-10 minutes then it will cut out. will restart right away with the cold start lever half way up and smoke for 30 seconds and then start the process over. Ive put new vro pump in, compreesion good, new charge coil and power pack in( they were weak but still running). had tinming check at wot was retarted 3 degress and had it reset to 18btdc. fuel system has been pressure tested as well as vucum test on line to remote oil tank. I'm thinking this might be as simple as bad plug wires or low speed jetting. Any ideas are very appreciated. Thanks in advanced

 

[Hooty]

Re: rude misfiring and stalling at idle when hot.

That miss-fire (spit) could be what is known as a "sneeze" and if it is, it's caused by a lean fuel/air mixture. The fact that it fires right back up when you raise the fast idle lever kinda confirms that (richer mixture). You might consider a carb overhaul.<br /><br />c/6<br />Hooty

 

[Solittle]

Re: rude misfiring and stalling at idle when hot.

What you describe points to crud in the carbs. Try thoroughly cleaning them and putting in new carb kits. Also see:<br /><br /> http://www.outboardrepairs.com/carburetors/

 

[dcolpitts]

Re: rude misfiring and stalling at idle when hot.

Thanks for the reply, the carbs have been rebuilt twice in the last 4months, 2nd time for air leaks. none found. plugs are wet and dark when they are pulled right after a stall. When lifting the lever I believe this opens the throttle plates slighty, and advances the igition timing at the same time. Also the smoke is blue, which leads me to believe that it is a rich mixture. I'll try to test the coils and wires with a heat test, it may be a failure when the engine gets up to operating temp. again thanks for the replies

 

[93bronco]

Re: rude misfiring and stalling at idle when hot.

dont miss the fact he has 2 auto spark wires he is using, in place of the solid core omc.

 

[OBJ]

Re: rude misfiring and stalling at idle when hot.

The auto spark plug wires have to much resistance for outboards. This causes poor spark for the cylinders connected to. Should replace with marine wires. Might solve the problem.

 

[BillP]

Re: rude misfiring and stalling at idle when hot.

I had a 1980 140 Johnson that displayed the same running problems. It was caused by removing the thermostat. It would idle fine when "dead cold" because the elec choke masked the problem. After the motor warmed up it wasn't cold enough to make the choke work at idle but still ran cold enough to spit, sputter and eventually cut out.