Evinrude out board

[ringo111]

Guys,I have 1990 140 hp evinrude ,problem I am having is it's idling .when idling it has a miss when idling ,after awhile it will stop all of a sudden,new plugs,compression is 150 on 3 cyc,and 140'. 3 plugs look clean one has black on it,if I take the plug out the engine seems to idle better on 3cyc than 4 .all 4 plugs seems to be firing ok.hope some body can solve this for me thanks

 

[boobie]

Re: Evinrude out board

Will the spark jump a 7/16" open air gap on a spark tester on all 4 cyls? If you pull one plug at a time do all the cyls drop off equally?

 

[ringo111]

Re: Evinrude out board

Don,t have spark tester.if I pull plug at a time,they don't drop of equally.

 

[oldrudedude]

Re: Evinrude out board

Is the plug from the cylinder that is not firing wet? If not you may have a blocked slow speed jet on that cylinder.

 

[ringo111]

Re: Evinrude out board

All four cyc are firing ,3plugs are clean one has black on it crabs were cleaned.I failed to say aim using a year old gas .does it matter

 

[oldrudedude]

Re: Evinrude out board

Put new gas in it.

Is the miss fairly steady or is it intermittant? Put it on the garden hose and muffs. Run it in the dark to see if there is spark arcing from the plug wire to the block. Or take the plug out, put the plug wire back on to it, lay the plug so it is grounding on the engine block, start the engine and observe the quality of spark across the gap. Is there any?..... is it orange?......... is it blue?

 

[ringo111]

Re: Evinrude out board

Color blue

 

[ringo111]

Re: Evinrude out board

Miss is iternmittant

 

[oldrudedude]

Re: Evinrude out board

Is the observed spark consistant or missing intertmittantly? If you can mooch a spark tester or a timing light you wood be able to tell more definitively the quality of the spark, the spark will weaken when under compression so the spark on that may not be strong enough to ignite the year old gas.

When did you clean the carbs and why are you using year old gas?

 

[ringo111]

Re: Evinrude out board

Seems to be consistant

 

[oldrudedude]

Re: Evinrude out board

May be weak spark but I think I'll put my money on restricted idle circuit on that cylinder. When you cleaned the carbs did you totally clean and blow air through all those little passages? What about the tiny holes that are clustered around the butterfly? They carry the fuel into the carb throat at idle. When I do my carbs, I use a small piece of .009 guitar string to ensure those passages are clear. Then blow them out with air.

 

[ringo111]

Re: Evinrude out board

Yes I blew out all tiny holes ,carbs were like new when I took it apart.

 

[ringo111]

Re: Evinrude out board

Thanks for your time and help

 

[ringo111]

Re: Evinrude out board

follow up it was a coil breaking down