2 black black spark plugs, 2 nice ones. What gives?

[BigB9000]

origional thread here:

Can't get a good RPM to get a decent speed
http://forums.iboats.com/showthread.php?t=269672

boat/engine in question is a 1967 holms, 15' flat bottom, bearing a 1978 115hp johnson outboard.

the left side side is nice and BLACk, the right side looks normal (both sets of plugs)

both left pugs: (the cleaner parts is where I touched them)

looks like a problem on the left bank no?

 

[ezeke]

Re: 2 black black spark plugs, 2 nice ones. What gives?

The black ones are the cylinders that are firing.

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

whatttt

really?


they are oily though. like, looks like it just dipped them in used motor oil out of my crappy old car.


keep in mind these plugs have 40 minutes of life on them

 

[Ezrider_92356]

Re: 2 black black spark plugs, 2 nice ones. What gives?

does your motor have 2 carbs or 1?

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

does your motor have 2 carbs or 1?

2. both working.

but, its both left cylinders that are like this, not one cylinder on each side

 

[Dhadley]

Re: 2 black black spark plugs, 2 nice ones. What gives?

If the two port plugs are black and sooty, the wires may be crossed. Either the primary wires or the plug wires.

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

If the two port plugs are black and sooty, the wires may be crossed. Either the primary wires or the plug wires.

checked, seems ok

 

[CharlieB]

Re: 2 black black spark plugs, 2 nice ones. What gives?

In your original thread I recommended that you test for spark on ALL cyl's.

Do you have a 7/16 bright blue SNAP? A lazy yellow arc, or nothing at all on the clean plugs?

You could have an ignition problem and be running on only two cyl's.

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

bright blue (and hurts)

I dont have a spark tester, I do the ground plug to block test.

all cylinders and plugs fire

 

[CharlieB]

Re: 2 black black spark plugs, 2 nice ones. What gives?

You are only running on the two left side cylinders, the right side is NOT running.

You say you have a HOT spark on ALL cyl's.

Then something has to bee wrong with the timing on the right side.

The timer triggers BOTH sides, the left is running correctly so that isn't the problem UNLESS there is faulty trigger wiring to the right side, in which case, you would NOT have spark.

Switch the power packs to see if the problem switches sides, if so then you will know that there is a problem within that pak.

Has there been any recent work done to this motor before you developed this problem?

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

You are only running on the two left side cylinders, the right side is NOT running.

You say you have a HOT spark on ALL cyl's.

Then something has to bee wrong with the timing on the right side.

The timer triggers BOTH sides, the left is running correctly so that isn't the problem UNLESS there is faulty trigger wiring to the right side, in which case, you would NOT have spark.

Switch the power packs to see if the problem switches sides, if so then you will know that there is a problem within that pak.

Has there been any recent work done to this motor before you developed this problem?

Power packs- isnt the wiring reversed on the 2 sides?

And they fire out of the water, any reason they wound not fire in the water?

 

[dajohnson53]

Re: 2 black black spark plugs, 2 nice ones. What gives?

bright blue (and hurts)

I dont have a spark tester, I do the ground plug to block test.

all cylinders and plugs fire

Buy a spark tester - the kind you can adjust the gap. I've been fooled by the ground the plug to the block test- it only shows you that you get a spark across the electrodes of the spark plug. You can see what appears to be a good spark on the plug, but it is not strong enough. You could easily think you're cylinders are firing, but they aren't. A spark tester will show you how big a gap it can jump with a sharp blue spark. Someone above mentioned 7/16 - that's what your spark should be able to jump, not just the plug gap.

If your local autoparts store doesn't sell it, call your local Snap On vendor. They always have them on their trucks and you can either have them stop by, or meet them at one of their regular stops. That's what I did - $10 bucks and you're good to go.

Also, within these forums there are instructions and photos of home made gap testers, which are also easy to make and use. I never made one, so I can't give you instructions though - but I saw it in here somewhere. Maybe search for spark tester or something.

 

[ezeke]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Follow the wire from cylinder number two; the wire should enter a two wire amphenol on the way to the powerpack. For that wire, what is the color between the amphenol and the powerpack?

 

[HighTrim]

Re: 2 black black spark plugs, 2 nice ones. What gives?

I agree with DaJohnson53, Ill bet when you install an inline adjustable tester, you will find an absence of spark on the cylinders in question. Plus this way is much easier on the brain cells.

The cheap single cylinder ones are good...



but for the 4 or 6 cylinders, I have found that the multi cylinder testers are nice to compare the spark between cylinders....



BTW, the pics of the plugs are gone, at least I could not access them to view?

The following is Joe Reeves method for making a spark tester.

(Spark Tester - Home Made)
(J. Reeves)

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas the!y could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:


..........X1..........X2

.................X..(grd)

..........X3..........X4

 

[Joe Reeves]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Attempted to view those s/plugs...... no longer there.

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Ill get myself a gap tester thing...

Also, I did a compression test again, heres what I have:


Left Right

top cyl 108 110

bottom cyl 90 60


Thats about right. hard to tell slight differences because the gage doesn't have ever number on it, just increments of 20

That ok? or good enough to run decently for the time being?

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Attempted to view those s/plugs...... no longer there.

Yeah, I think photobucket yanked them because of there massive size

Ill get them back up soon

 

[HighTrim]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Sorry, but you may have some seized or worn piston rings. Others will verify, but due to the compression readings, and the condition of the plugs, that is what I would lean to.

May need to pull the head to have a look.

 

[BigB9000]

Re: 2 black black spark plugs, 2 nice ones. What gives?

Sorry, but you may have some seized or worn piston rings. Others will verify, but due to the compression readings, and the condition of the plugs, that is what I would lean to.

May need to pull the head to have a look.

Yeah......

my friends 110hp johnson had a completely dead cylinder, like 3psi dead.

It was a little hard to start, but lasted for year and years (10+) like that. untill a nother cylinder died, while lower unit went. now he has himself a 2008 115 (?) oil injected johnson. Really really nice running & sounding...

So Im woundering if the low cylinder is really THAT big of a problem

 

[HighTrim]

Re: 2 black black spark plugs, 2 nice ones. What gives?

A decarb may bring up the bottom port cylinder, but the starboard is pretty low. I would imagine it has a worn ring, but could be wrong. You wont know until you pull the head.

These others guys helping you have alot more experience than me, and will be able to guide you.