'74 135 charge coil test

[patagoniapete]

I have a 1974 Evinrude 135 Strangler. The tach on this boat doesn't work and so I tested the rectifier which tested bad. I ordered the rectifier but, after reading some posts here, it made me think that I should test the charge coils on the stator as well. The book calls for some kind of "neon test" and I have no idea what that is. Do they go by another name? Is it an outdated test or is there just another way that we test them now?
I read on one of the forums to test the resistance of the charge coils using #7 & 8 leads off of the power pack. They said the ohm's should read between 550 and 700. I got a reading of 749. Is that too far out of range?
Are there symptoms that the boat should exhibit if the charge coils are bad? The problem that I have been having with the boat recently is that it takes a good 30 seconds for it to accelerate at WOT, but once it gets up there it does great. I rebuilt the carbs and have ordered a fuel pump but haven't had time to check the results on the water yet. I'm just worried about the charge coils because they're $300 and I really want to make sure its necessary before I throw that kind of money at this thing.

 

[emdsapmgr]

These old factory service manuals have a lot of overcomplicated ignition troubleshooting techniques. Some, involving neon testers and other stuff that most of us don't have. In the mid 80's they updated their ignition troubleshooting logic, but never re-engineered it to these older units. This current website has specific troubleshooting that has been re-engineered back into these old units. cdielectronics.com Instead of ohms testing, they provide condemning voltage requirements for cranking tests. Armed with the specs in this guide, a special "peak-reading" voltmeter, you can test for cranking (250 rpm's) output voltages on both the timer base and the ignition side of the stator. If the output voltages are low, replace the part. If they meet minimum output voltages, then the power pack becomes prime suspect #1. Voltages expect might be something like this: stator- minimum of 150 volts, timer base-minimum of 0.3 volts, but check the website for your engine's specific numbers. Coils are generally pretty reliable and they can be swapped in order to test them. The problem with this commentary is that you say the engine runs fine at WOT. Usually, it won't run WOT if any of these ignition components are not in tip top shape. Hopefully, you are basing your running issues on actual water tests, and not how the engine runs sitting on the trailer in the back yard.

 

[patagoniapete]

Thanks for the feedback. I actually took a look at the cdielectronics website today. I plan on running some of the tests when I get a chance.
As far as the WOT, here is what's happening. It runs a little rough when I have to creep through the no-wake zones. When I push the throttle all the way down, it will take about 30 seconds before the boat accelerates to top speed. Once at top speed it does great and it planes right out, but it just takes forever to get there. I'm hoping that rebuilding the fuel filter fixes this issue (When I squeeze the primer bulb it never really gets rock hard). I only bring up the charging coils and stator components because the rectifier is bad and I have read that they can take out the charging coils when they go bad.
As far as the stator goes, does it perform more than one function? Is it possible that part of it goes bad (ie. the charging coils) while the rest of it still functions properly?

 

[emdsapmgr]

The stator has two sets of coils. One set makes ignition voltage, the other set makes current to recharge the battery. These two systems are independent of each other and don't interact. The latter set sends current to the rectifier which then sends charging voltage to the battery. It also sends a pulse signal count through the grey wire which is left stubbed out inside the contorol box. That wire is actually the signal wire for the addition of a tach. There are two different methods to verify these two stator coil systems. The cdi website has good troubleshooting information on the ignition problems. The factory service manual should have a procedure to verify current output on the charging (battery) side. Unlikely the ignition is bad if the engine gets up to WOT. If you have not disassembled and completely cleaned the carbs, you may want to do that. Your carbs have idle and main jets. I'd pull them out and visually inspect them for any dried up gas gelatin. You will need some aerosol carb cleaner, as that's the best thing to clean any dried fuel inside the carb passages. (Bombardier's aerosol Engine Tuner also works.)

 

[patagoniapete]

The amount of knowledge shared by the people in these forums never ceases to amaze me. Thank you for the clarification. Unfortunately, this means I may have two different reasons to replace my $300 stator. Like you said, my ignition side is probably fine, it's the charging side that I'm worried about. I do want to have a functional tach so if the rectifier doesn't work, I'll just bite the bullet. Thanks.