Intermittent Spark on Cylinders 1 and 4

[ckraker]

I have a 1974 135hp Evinrude. v4

I have been having hard starting issues, and idle issues. WOT there are no problems. While trying to set the timing today I noticed that my timing light would only work intermittently. Well turns out it's because my number one cylinder wasn't firing. I did a spark gap test and found cylinders 2 and 3 work well all the time. But 1 and 4 sometimes work and other times don't fire at all, When they are firing (i can tell by seeing the spark in the gap tester) the engine runs great.

I have a service manual but all their test require a neon spark tester..... whatever that is. Seems odd to me that the problem is on separate banks of the engine.

I also switched spark plugs and still had problems with the same cylinders.

Anybody have any ideas?

flywheel magnet? Sensor Gaps?

Thanks!

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

Also stator is oozing.

 

[F_R]

Re: Intermittent Spark on Cylinders 1 and 4

Oh well, you just answered your own question. That stator is junk. Ordinarilly, I would have said sensor gap, but there is no sense in even messing with that till you fix the obvious. It will probably be fine with a new stator.

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

I want to make sure that it isn't going bad because of something else. 400 dollars is an expensive experiment. Battery is charging a little, so I'm not sure it's a bad rectifier. Unless you can have a half bad rectifier.......?? Is that possible, I know a bad rectifier will melt a stator.


Maybe someone could explain to me why this would only cause two cylinders to be intermittent.

 

[F_R]

Re: Intermittent Spark on Cylinders 1 and 4

Because those two coils just happen to be the weakest ones would be one explaination. BTW, one and four are fired by different sensors, which kind of blows the first idea.

There is no need to wonder about the rectifier. Simply test it. Your manual should show the procedure. There are 4 diodes in that rectifier, and two tests for each diode. It must pass all 8 tests to be good.

If it is any consolation, nearly all of those 1974 stators went bad within the first few years. Yours has done an outstanding job to last this long---unless it is not the original.

 

[boobie]

Re: Intermittent Spark on Cylinders 1 and 4

The neon spark tester was replaced by the peak reading volt meter. You can also use a multi- meter with a DVA adapter. Go to CDI Electronics.com. They have good test procedures.

 

[emdsapmgr]

Re: Intermittent Spark on Cylinders 1 and 4

Agree on the volt test on the stator. There is a similar volt test for the output on the timer base.

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

Okay-- Last night I pulled the flywheel and visually inspected everything. It appears that I already have a newer Stator (painted Green). The ignition charge coils are definitely oozing, however the output was just over 300 volts DVA and that was just while cranking! The stator was putting out about 40. Both of these seem to be in spec. I had the same problem last night when I ran it. except that I couldn't get spark on any cylinders except #2. Then suddenly for no apparent reason they all start firing????? I also tested the rectifier (as people have mentioned that it can cause ignition problems.)

emdspmgr -- mentioned the timer base voltage... could someone further explain?

Also need to test the coils themselves, although they visually look really good (no cracks) and I hear they are rarely the problem.

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

I should also note--- I started the engine on cylinders 2 AND 4. 1 and 3 had no spark. Then I pulled the boot off of number 4 and immediately number 1 and 3 started firing.....Random to me but maybe one of you guys have seen this before.

 

[emdsapmgr]

Re: Intermittent Spark on Cylinders 1 and 4

40 volts out of the stator sounds low. I believe the minimum cranking output should be 150.

 

[boobie]

Re: Intermittent Spark on Cylinders 1 and 4

I've seen your weird firing probs yrs ago and it turned out to be the power pack. Just check all the other outputs tho' before replacing the pack. And I've also seen stators that had the melting coil prob and they still worked.

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

Boobie, nice name. Thanks for the advice. Exactly what I was hoping someone would say. What causes these packs too go bad?

 

[boobie]

Re: Intermittent Spark on Cylinders 1 and 4

Sometimes just good old quality control. LOL.

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

40 volts out of the stator sounds low. I believe the minimum cranking output should be 150.

Maybe someone needs to take me to school. but isn't the 150 volt minimum for the brown and brown yellow stator wire reading. (the wires that feed the Power Pack) The 40 volt DVA Reading I got was from yellow to yellow for the battery charging system.

Anyway-- I have 300 + volts feeding into the power pack. I have a 1.5 volt reading from the sensor wires black/white to black. So I'm getting my trigger. However----- I'm getting a max of 12 volts DVA when I take a reading from any of the orange coil wires to ground or black/white white/black to ground and I think I should be hitting 150 off of those. So I ordered a Power Pack.
I can't believe that the engine actually starts... with only 12 volts being fed to the coils!

 

[emdsapmgr]

Re: Intermittent Spark on Cylinders 1 and 4

Yes, the power pack leads from the stator are the brown, brown with yellow tracer. Your reading in the ignition side of the stator should be ok.

 

[a_kraker99]

Re: Intermittent Spark on Cylinders 1 and 4

Okay, I am ckraker's brother. I have been reading this thread along with him but haven't posted. I have a couple questions I am hoping someone can clarify for me.

1. Using the DVA adaptor we are getting a reading of 10-12 volts on the yellow output wires from the power pack to the coils. Is that something you see with a bad power pack or are we just testing it wrong?

2. We cant get the spark across a 7/16 air gap but if the engine is running and I touch the plug boot, I will get poked. How can it jump through a rubber boot but not an air gap?

 

[emdsapmgr]

Re: Intermittent Spark on Cylinders 1 and 4

The factory manual for your engine does not list volt outputs for the 1974 power pack. Later (1990) OMC service manuals list outputs from the newer power packs as 150 volts while cranking, 230 volts while running. Am not sure what the correlation of this information may be to your 74 engine.

 

[ckraker]

Re: Intermittent Spark on Cylinders 1 and 4

is the power pack output (to the orange coil wires) voltage supposed to be read by connecting my dva black lead to engine ground and the red to one of the orange output wires?

 

[a_kraker99]

Re: Intermittent Spark on Cylinders 1 and 4

We are back, that is if anyone is even still paying attention to this thread.

We just replaced the power pack and realized the for some reason we had to reverse the DVA testing wires to get the correct reading on the orange wires to the coils. So the old one may or may not have been bad.

What we did find out was that there are 2 coils that will not jump a 7/16 air gap and 2 that will. 1 on each side of the engine, so it doesn't have anything to do with the sensors. We also switched the power pack wiring and put the coils on different plugs to make sure it wasn't the power pack output or a bad plug causing the problem.

If you touch the top of the 2 bad coils while it is running you will get a poke. I would assume that is a bad sign. What causes them to short out like that and should we just replace the 2 or is it best to just replace them all at the same time?