Mystery cylinder problem, HELP needed! 1971 Evinrude Misfire on idle

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Thanks Bonair, I hope someone can throw more ideas at me - I am just stuck right now.

 

[Daviet]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Just a few thoughts. If you are sure it is #3 giving you a problem, I would pull the flywheel and check the dist cap and rotor, making sure the contacts are clean with no carbon build up. Remove #3 wire and check it carefully and make sure there is not a spot where the the insulation is worn, maybe at a clamp. Check the wire at both ends for corrosion. Clean and check point adjustment.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Just a few thoughts. If you are sure it is #3 giving you a problem, I would pull the flywheel and check the dist cap and rotor, making sure the contacts are clean with no carbon build up. Remove #3 wire and check it carefully and make sure there is not a spot where the the insulation is worn, maybe at a clamp. Check the wire at both ends for corrosion. Clean and check point adjustment.

Have not tried that yet, thanks for the input Daviet. Will get on it today.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

As I am waiting on my old man to try Daviet's suggestion, I found some irregularity while checking out throttle cam adjustments. Here are the photos of my findings, the nut is good, however the washer is all bent up, and it seems like the plastic casing inside is cracked. Take a look, tell me the importance of this and if it could cause a problem.

Also note, that the top scribe mark on throttle cam does not align with center of cam follower roller as roller makes contact with cam.

Could this be a way to even partially resolve my problem? Improper cam adjustment?

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Just a few thoughts. If you are sure it is #3 giving you a problem, I would pull the flywheel and check the dist cap and rotor, making sure the contacts are clean with no carbon build up. Remove #3 wire and check it carefully and make sure there is not a spot where the the insulation is worn, maybe at a clamp. Check the wire at both ends for corrosion. Clean and check point adjustment.

Daviet, without taking the flywheel off I can tell that there is some kind of leak going on connector for #3, while others are dry. Also while removing my motor cover off there is a large black spot on the foam, precisely where the #3 rests. This was not present before.

This investigation it taking me somewhere, but I am not sure where yet!

Is this an indication that the #3 is getting flooded?

Observe :

 

[emdsapmgr]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

The wave washer is ok. The factory used that type of washer to take up slack-the bolt bottoms out, but does leaves a little slack in the throttle cam. The wave washer is designed to reduce the slack, yet permits the cam to move freely on the stud. The bushing normally has a factory crack cast into it. It lets you slip it over things and provides a channel for the lubricant. The black spot on the inside of the cowling foam is very interesting. It's possible the #3 plugwire is bad and is shorting (arcing) to ground inside the hood at that location. It's not far for spark to travel to the cowling latch bracket, where it could go to ground through the aluminum lower cowling cover. A new plugwire may solve the problem. You might be able to duplicate the arcing with the cowling off. Ground a screwdriver on the lower cowl and move it within an inch or so from the spark plug wire while the engine is running. See if you can get the wire to go to ground on the screwdriver.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

The wave washer is ok. The factory used that type of washer to take up slack-the bolt bottoms out, but does leaves a little slack in the throttle cam. The wave washer is designed to reduce the slack, yet permits the cam to move freely on the stud. The bushing normally has a factory crack cast into it. It lets you slip it over things and provides a channel for the lubricant. The black spot on the inside of the cowling foam is very interesting. It's possible the #3 plugwire is bad and is shorting (arcing) to ground inside the hood at that location. It's not far for spark to travel to the cowling latch bracket, where it could go to ground through the aluminum lower cowling cover. A new plugwire may solve the problem. You might be able to duplicate the arcing with the cowling off. Ground a screwdriver on the lower cowl and move it within an inch or so from the spark plug wire while the engine is running. See if you can get the wire to go to ground on the screwdriver.

Thank you for the info on the wave washer, and the plastic casing! I will put them back in - I will go and buy a new plug wire tomorrow. Will let you know the results Emd! Thanks again.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Got a bit of confusion again, and a really newbie question : when you say plug wire, you mean this? For some reason I think I am mistaking it with Coil.

Also, why are the two on cylinders #2 & #4 shorter than the ones on #1 & #3??? Take a look :

 

[dc095]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

yep, thats a plug wire

 

[Faztbullet]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Does number 3 have a heli coil in spark plug hole??? Also are you running the L76v or L77jc4 plugs?

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

The bushing is a split bushing and that is a wave washer all factory. Does number 3 have a heli coil in spark plug hole???

Hey Faz, what is a heli coil? Running on Champion L76V plugs.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

I'm sure you guys cant tell much from this video I made, since the sound DB is overpowering. When it bogs a little, it vibrates the motor. Will do another with the drop test.

But here it is anyway :

http://www.youtube.com/watch?v=leTsAZf9vHc

 

[jigngrub]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Diagnosis through trial and error/process of elimination is going to take a while.

Instead of replacing just one plug wire, replace them all... and while you're at it go ahead and replace the distributor cap, points, condenser, and coil too. Then if the problem still persists you can pretty much rule out ignition/electrical. Your motor is old and replacing these parts is only a good thing. These parts aren't that expensive and if it fixes your problem you're money ahead.

Did the guy that sold you the boat just happen to say that all the motor needed was a tune-up?

btw, a helicoil is a threaded insert at the spark plug threads. When someone strips the threads for the spark plug in the head, they drill and tap the hole and install a helicoil to repair the stripped threads.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

New things for tonight :

Main coil had a loose spark (did a test in complete darkness) fixed it and its good now.
Performed the drop test again on #3 and still the same problem. It would not drop at all. Checked for spark again - spark was good.
Tried swapping plug wires to see if they were faulty, same problem on #3 again. Wires are good.

While all the other cylinders droped the #3 would not. This is still quite a mystery to me.

 

[Daviet]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Just a few thoughts. All it takes for your cylinder to fire is timed spark, which you should have because the other cylinders fire properly. Compression and fuel, which one is missing?


You can use a timing light to check the cylinder is firing.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Just a few thoughts. All it takes for your cylinder to fire is timed spark, which you should have because the other cylinders fire properly. Compression and fuel, which one is missing?


You can use a timing light to check the cylinder is firing.

Compression is good, and spark is good...fuel problem is my only thought.

I will borrow a timing light this week, can I just put it on #3 and than check? My pops adds : So far we suspect it is indeed a fuel problem. Most likely carburetor.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

An important element I forgot to add :

The #3 plug wire was not screwed in at all, on the distributor side! Could this lead to distributor cab contact for #3 failure? Any way to check the cap, without taking the flywheel off???

Thanks for all the input so far Gentleman.

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Giving it a lot of thought today...

Guys, COULD a dirty carb cause ONE lower/bottom cylinder that has spark to FAIL?

 

[Sander]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

I guess nobody can confirm my question, or perhaps I am asking too much

Ok, I am going with my instinct and enter a no mans land of carburetors. Going to start taking it apart, and take pictures as I go along...with me luck.

 

[jigngrub]

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

Re: Mystery cylinder problem, HELP needed! 1971 Evinrude

I guess nobody can confirm my question, or perhaps I am asking too much

Ok, I am going with my instinct and enter a no mans land of carburetors. Going to start taking it apart, and take pictures as I go along...with me luck.

When you're done with that you'll want to take it to a shop and have a certified mechanic do it right.