1993 140 v4 evininrude ignition?? problem

[dusky]

My engine has started missing at idle and also at 2000-3000 rpm. It runs for a few seconds and then it has a miss, almost like the whole ignition shuts down for a few milliseconds. It then puffs out some smoke like it clears out the cylinders and runs a few more seconds before it does it again. It has been sitting about 8 month so I thought I had a carb problem, cleaned all four and no change. I tried pulling off plug wires and cranking it up with one off and it naturally skipped but the intermittent miss was the same with each one off. Any ideas?

thanks,
dusky

 

[HighTrim]

Re: 1993 140 v4 evininrude ignition?? problem

Just to start I would check the compression and spark.

 

[Dhadley]

Re: 1993 140 v4 evininrude ignition?? problem

Are the T-stats in? What spark plugs are you suing? What grade fuel?

 

[dusky]

Re: 1993 140 v4 evininrude ignition?? problem

Thanks for the reply. I do have the t-stats in and the plugs are 77jc4. I checked the timing today on all the cylinders, I could see a miss in the light every now and then but it wasn't constant with the engine miss. It seemed like 2 and 4 weren't quite as even as the odd #s. The compression is 120 on all cyl. The boat has been sitting and the gas is old. It had 87 octane in it and I added some fresh 89 and a bottle of octane boost. I think tomorrow I will try connecting a aux. tank with 93 and see what difference that makes. The engine has always run perfect but I have never let it sit this long and I didn't add fuel stabalizer. Should i try anything else?

Thanks again,
Dusky

 

[HighTrim]

Re: 1993 140 v4 evininrude ignition?? problem

93 is not necessary, stick to regular 87 octane. Definately get rid of that old fuel.

 

[flabum]

Re: 1993 140 v4 evininrude ignition?? problem

Sitting for 8 months....it's worth the time and effort to pull the carbs, diassemble them and clean them out.

 

[wavrider]

Re: 1993 140 v4 evininrude ignition?? problem

Flywheel key sheared and slightly out of time?

If all else fails and the new gas still does not produce any better results, check the link n sync on the timing advance and carbs, check individual spark with timing light or make a spark tester where you can check all cylinders for spark at the same time to see which if any are not sparking consistently.

Try starting it after dark and look for any stray sparks jumping from the spark plug or coils. Check all your coil grounds for corrosion, cleam connections with a brush or file and re-install.

Intermittent problems can be a bear to diagnose, the above listed is just a few I have run into and the starting after dark helped me solve a bad spark plug wire problem, I would never have seen it jump spark in the daylight.

 

[reeldutch]

Re: 1993 140 v4 evininrude ignition?? problem

get a can of carb cleaner and run the motor.

when it starts coughing spray the carbspray around different spots on the outside of the carberator and intake and crankcase halves.

if there is a vacuum leak the motor will start to pick up rpms when it sucks in the carbcleaner trough the leak.

dont do it with regular premix the effect is not strong enough.

if the engine doesnt react than you have no vacuum leaks.

move on to trouble shooting.

good luck

reeldutch

 

[Chris1956]

Re: 1993 140 v4 evininrude ignition?? problem

Dusky, Is it a lean "sneeze" at idle speed? If so, richen the idle mixture a bit.

 

[dusky]

Re: 1993 140 v4 evininrude ignition?? problem

Well, I tried the gas and no change. I decided to check the firing again. This time I checked each cylinder at about 2500 rpm., the miss is worse there. it turns out that the #1 cyl. is the main culprit. When the miss happens, the timing light goes completely out on #1. The #2 is the next best with just a slight blip every now and then. #4 is almost perfect and #3 fires perfectly and never changes no matter how bad the miss gets. I swaped the coils around to see if it moved with the coils but It did not. Power pack or pickup coil?

I appreciate the help.
Dusky

 

[wavrider]

Re: 1993 140 v4 evininrude ignition?? problem

May be time to pull the flywheel, see if anything is loose or damaged wires, loose magnets, any and all potential there, the good thing is you are getting spark, so it most likely may be something simple under the flywheel, maybe a dirt dopper nest? I have seen then in idle exhaust bypass ports before, good luck