Do I have Weak Spark caused by a bad stator?

[jstatham]

Hello everyone. I am still fighting my 1994 Johnson 120 TLERC. It is a long story but I have replaced the lower Crankshaft bearings, New upper and lower seals,Plugs, New fuel Pump,Rebuilt carbs, WaterPump etc. SO basically I am at the point now where I believe I have fixed all the previous problems and I am now down to what I believe to be a bad stator. Here is what I did today.

1. I performed a spark test and from what I am seeting it looks like I have a very low spark. See video below. I made the spark tester out of a Aluminium can lid and a ford Distributor cap. I was expecting to see a much brighter and wider/larger spark.

http://www.youtube.com/watch?v=i7gkkxyFUiU

I fired it up and it is missing and after you check the plugs they all seem to be getting enough fire but the top right plug (standing behind the motor is always wet). All the others seem ok.
Here is the video of it running.

http://www.youtube.com/watch?v=Ugn0rInIhJU

I swapped coils, Plug, Wire on that cylinder and it is always soaking wet like it is just not firing hot enough to ignite. Is it possible that the carb could be flooding that cylinder?

top right bottom right

top left bottom left



1. I then followed the OEM rapair manual and checked the ohms on the stator and it showed 580 ohms and the manual said it should be 480 +/_ 50 ohms. So the max is 530 and I am at 580 so that is 50 ohms over. I then test the volts output with a homemade DVA adapter that I made follwing the specs I found online. I am assuming it is working properly but not sure of how to test it. If anyone knows how please let me know. Anyway it showed 162 volts and the book says it should be putting out 175 or higher. So once again I am assmuing that the stator is bad. I would really like to know 100% before I drop that kind of cash.

Here is a video of the test. I say hooked to the power pack but meant stator.
http://www.youtube.com/watch?v=XbOGkv2NE5A



I then tested the timing trigger and it all tested out fine to spec.

I did not test out the power pack because I did not have the Stevens Instruments PL-88 tester or a 10 watt resistor.

So I guess the bottom line is can you see anything I am missing or should try before I buy a stator or did I diaganos everything correctly and a new stator should solve my problem. They only other thing I can think of would be to swap that carb to another cyclinder but I don't think it is a fuel problem. Thanks in advance for all your help.

 

[Bosunsmate]

That top left plug looks awful, carboned up, Are you running the VRO still?
Hard to say about the top right plug, ive never tried a ford distributor cap. Have you checked it can jump a 7/16 gap on that cylinder? If it can and the plugs still wet then id be putting a match to it to check its not water mixed with fuel and if that checks out then id be checking timing

 

[Bosunsmate]

Have you checked compression? Just wondering why that plugs so dirty

 

[jstatham]

I have checked the compression and all 4 cyclinders are at 120 psi. That top left plug is so dirty because I had an upper seal leak. Believe it or not these wre brand new plugs a few monts ago. Like I said I have had problem after problem. I am running fresh gas directly out of a temp can. I have tried several spark testers and it will barely make the 7/16 jump and in fact the tester I made is a hair under a 1/2 and it is not as bright as I think it should be. Here is the link that gave me the idea for the tester and as you can see his is firing much hotter and brighter than mine,

http://s691.photobucket.com/user/snapc33/media/boat/MVI_1450.mp4.html

 

[racerone]

Spark looks good.-----------Have you looked for an issue with the crankshaft sealing rings.----------------Not the same as the upper and lower crankshaft seals.-------------Your motor is actually 4 seperate motors with a common block and crankshaft.------------Each cylinder has it's own crankcase and it is sealed from the others as far as the air is concerned.--------------Looks to me like that cylinder is running cold and will not keep the plug " clean and dry " so to speak.

 

[F_R]

First, I don't see anything wrong with your spark. Second, what motor is the other guy using his dist cap tester on? His spark looks unusually blue and fat----not characteristic of a OMC/BRP mag CD ignition. BTW, that is a cool idea for a home made tester----never saw that before.

You ask if the carburetor can be flooding that one cylinder. Yes, of course it can. So can a defective spark plug.

Your stator would be the LAST thing I would suspect. Just my opinion.

 

[Tim Frank]

What plug are you using?

 

[jstatham]

I am using the Champion QL16v plugs that it calls for but I have also tried ql77jc4 all the plugs behave the same. I plan on getting a set of new ones once I get this figured out. What are your thoughts on the stator being out of spec per the oem manual on Ohms as well as voltage output? I have swapped the carbs in the past while fighting other issues but have not done it recently. If I remember correctly it was the same results a wet plug. Also if the sealing rings were bad wouldn't the compression be low?

 

[WrenchHead]

It looks to me like either a rich carb mixture to that cylinder or the cylinder has a problem. It would be unusual to have a weak spark to one plug. As a test, switch plugs with another cylinder and switch carbs with another cylinder. Now if the plug fouls you know it's the cylinder. Bad seals?

 

[racerone]

Crankcase compression and compression in the cylinder are totally seperate things.--A bad seal ring will not show up in a cylinder compression test.

 

[jstatham]

I can swap the carbs and plugs no problem. The plugs where brand new in July when I bought this motor. Is there another way to test for bad ring seals or is it just process of elimination? What really stinks is I had this motor completely torn apart to install the lower bearing. I could of changed the rings seals easy.

 

[daselbee]

If it were me, I would do the following free testing:

1. Put a timing light on each cylinder in succession. Look into the light with engine running. Look for inconsistencies in the spark...erratic flashes, missing flashes, etc. All four should be the same, even flashing.
It may be my imagination, but on the dist cap test, some of the sparks look erratic and missing, in particular, the one at the 2:00 o'clock position. But it may be just how I am seeing the video. Hard to tell. But it is easy to tell when looking into the timing light.

2. Index the flywheel, and check timing when running on all four. For your debugging purposes, and for this particular test, idle timing at or near TDC is fine.
You want to verify absolutely that when #1 is at TDC, the plug for #1 fires, and that #1 is not firing at any other time but TDC. TDC and TDC only, I guess is a way to put it. Same with the other three.

Those two tests will tell you if there is double firing of the pack, if you have the ignition system wiring hooked up correctly (orange coil primary wires right), stuff like that.
In my opinion, the DVA voltage of 162 is low. It should be upwards of 190. Just for grins, read the stator brown pair WITHOUT the DVA.....just direct AC volts on the meter, and report back what it reads.

You can test your homemade DVA adapter by setting it all up, and reading the voltage from the home wall socket. It should read about 170v using the DVA.

 

[jstatham]

Thanks I will give all this a try. I also just talked to my buddy and he told me to also check and my sure the fuel primer is not constantly dumping fuel into the cylinders. The one at the 2:00 position is the #1 cylinder that's always wet.

 

[daselbee]

If it is not firing consistently, it will look wet. Also, is it just me, or do the other plugs look sooty...gray soot? They look weird to me too.

You can test primer solenoid leaking by clamping off the incoming fuel line to the primer solenoid. I use needle nose vice grips, adjusted perfectly so as to clamp off the line, but not smash it flat. The incoming fuel line to the primer solenoid is the bigger one of the three. The two little lines go out to feed the cylinders.

 

[jstatham]

I will give that a try and see if I get any change. I hope it is something simple.

 

[daselbee]

I happened to see your other video. It is about 1:30 mins long, posted yesterday. I think you have ignition problems...sparks occurring out of proper time.

Are you sure you have the orange primary wires hooked to the correct coils? On a V4, and I think this is right.....the top coils have the orange/blue stripe, and the bottom coils have the orange/green stripe. The other possibility is that the top coils have a plain orange wire. But I know for sure the bottom coils have orange/green.

As an example, it is very easy to swap #2 and #4 on a V6 looper. And it will run like crap. Sort of sounds the same to me. Usually, tho, when the orange primaries are swapped, the engine will backfire loudly out the prop. I do see some backfiring/kicking when it is idled up.....you got ignition problems, and I don't think it is simply weak ignition....something is sparking out of time. Indexing the flywheel will prove this out.

 

[jstatham]

The video you saw was before I found that the ground wire on the power pack was almost severed. I repaired it and it did run better. If you look at the attached picture I am pretty sure it is wired properly. The orange wire will almost only fit 1 way. With one be short and 1 being long.

 

[Bosunsmate]

I dont think its crankcase compression because if it wasnt sucking fuel in, the plug wouldnt be wet
I would light that wetness to check its pure fuel/oil and thus burns instantly, to make sure its not a small exhaust or head hasket water leak spraying on to it.

 

[jstatham]

Hopefully this weekend I am going to have some time and I am going to do the following.
1. Install 4 brand new Champion QL77JC4 plugs
2. Swap the top 2 carbs and quadruple check the floats
Fire it up and see what happens
3. Check out the fuel primer and make sure it is not just flooding the engine. Pinch it off as well as pull the lines and see if it is constantly pumping.

4. If I still have the same problem I will get a timing light and see if I am hitting on all the cylinders
If all this checks out fine I guess it is time to open the head gasket up and do some looking around?

How does this sound?

 

[Faztbullet]

Dont know where you got info on plugs but they are wrong type, all V-4 loopers from 1986-2001 use QL78YC. Try correct plugs first......