Tow of shame!! 1972 Evinrude 65hp no spark

[tx1961whaler]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

You can use the o'scope to measure peak voltage. It's kind of difficult to explain quickly how to use it, but here goes:
hook it up using a BNC cable (scope side) with 2 alligator clips on the end (engine side). One alligator clip is ground (shield), and the other is the signal (center conductor of the BNC).

The big knob on the left is the vertical scale control. It controls how many volts/division are on the scale. Set it according to the maximum voltage you would expect the signal to be, like you were using a voltmeter. Set to coupling button to AC.

The big knob on the right is is the horizontal scale control. It controls the amount of time/division that the scope trace is traveling at. If you set it for a longer time, the scope trace travels more slowly, and you can capture a longer pulse, but it may miss short pulses.

The trigger level control determines the voltage at which the scope's horizontal trace will "trigger" and start reading when you move that know, a flat trace or arrow should show up on the screen to show wjere the trigger level is.

To see if the scope is working hook the "signal" alligator clip to the calibration lug on the front of the scope. There should also be a ground lug. The cal lug has a preset signal coming out of it (probably printed below the lug) and you should be able to get the scope to show the signal, normally the first time by randomly twisting the vertical and horizontal and trigger knobs until something shows up

If you can never get a trace line going across the scope, then it may be broken.

 

[jay_merrill]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

Here's why you don't ever want to hold a spark plug wire while testing -

Your stator puts out 300 Volts AC, sends it to the the power pack, which then converts it to DC voltage and sends it to the ignition coils. The ignition coil then steps the voltage up to 30,000 volts. While the amperage is low in relationship to the voltage, if there is a break in the insultation, or the spark arcs from the open end of the boot to you, while looking for a ground, you are going to get zapped! I've never done this but I'm told that it isn't exactly fun!

The advice to get a spark tester is good too. You can test with just a grounded plug, but the tester shown in the above pic works really well, and is very inexpensive. If I remember correctly, I paid a few bucks for the one I have now, at Autozone.

As for the test equipment detailed in the manual that I sent to you, bear in mind that most of it is pretty much obsolete. I have been able to troubleshoot my motor pretty well by just doing the ohms tests, but the tests that you can do with a DVA meter are probably better. Some of the guys here can help you with what to do in this regard.

While you are doing all of this, you might want to do a compression test, just to see where your powerhead is from a mechanical standpoint. If the motor has been well taken care of, and doesn't have thousands of hours on it, it is not unusual to see readings of 130 - 140 psi, sometimes even more. If you see such numbers, and your gearcase is good condition, this motor can last you a long time, so putting some money into the ignition could be a good investment.

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

tx1961whaler, thanks for the info on the oscope! Now I think I have some old cable at work with bnc connectors I can solder some alligator clips to...

jay_merrill, thanks again. That's a good point to do a compression test just to see if the motor is worth putting $$ into. So what did replacing almost your entire ignition system end up costing you, if you don't mind me asking?

 

[jay_merrill]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

I have to answer this from memory, but I think the three coils were about $100, the power pack was about the same, and the timer base was about $230. As I mentioned previously, I still haven't replaced the stator, but I see them advertised for about $160 - $170. You can also get all of this stuff from your local OMC/BRP dealer but with the exception of the coils, you'll probably be getting aftermarket parts anyway, and you will pay a lot more for them.

My advice is to shop around because CDI parts are distributed through quite a few retailers. I have seen a pretty broad range in pricing and shipping costs, so a bit of time surfing the net for the best deal, is a good investment. As always, pick your internet retailer with care to avoid scam artists and unsecure CC transactions.

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

So I pick up a compression gauge and a spark tester on the way home from work yesterday. First evening I have some time to work on the motor. Decide to check compression first-- turn the key, nothing. Turns out I stupidly left the key in the on position last time I was testing the motor. Hope I didn't damage the battery-- took all night to charge it back up.

So I take the time to get the oscope working-- figured out how to do voltage checks with it. And I familiarized myself some more with the ignition system. I plan to do the ohm tests listed on 4-11 of the manual tonight. A few questions--

The manual says to use a neon light tester to check the power pack. An online search I did found a question on another forum about a non-starting 72 Evinrude 85HP. Joe Reeves said to check the power pack with a 12v light bulb, connected to each coil terminal on power pack and ground. Steady light on all 3 means the pack's ok. Would this work to check my powerpack?

Questions about the key switch-- jay_merrill said my problem is likely the key switch or the power pack. This might be a dumb question, but if the key switch is cranking the starter successfully, how would it cause no spark? Isn't engaging the starter its only purpose? I'm guessing current needs to flow through the key switch all the time, and that can fail while the switch still works to crank(?) And in the manual it says in order to test the key switch, remove black/yellow wire from power pack terminal 6 and crank key switch to see if there's spark. But the wire on terminal 6 is the key switch wire. Wouldn't that disable the switch entirely?

 

[tx1961whaler]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

With the o'scope, if you're making regular DC voltage checks (not looking for pulses), the set the coupling to DC. You probably already figured that out already.

 

[jay_merrill]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

Here's how I understand the issue of the key switch - if I'm off, I hope Joe or some of the other guys will chime in.

The start circuit and the "on" circuit in the key switch are distinctly separate. When the key is in the off position, the circuit going to the number 6 terminal grounds the output side of the power pack. When the key is in the "on" position it is not supposed to ground, but if the switch is defective, it does. By removing the wire at the number 6 terminal on the power pack, you eliminate the ground in a defective switch. Since the alternator (made up of the stator and the flywheel) will put out current as soon as the motor cranks, once this problem is eliminated, spark will be present on all three cylinders, if the power pack is good.

The start circuit in the switch merely serves to send voltage to the starter solenoid to engage it. Whether the "on" circuit is functioning properly or not is not a factor in the ability of the solenoid and starter to engage.

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

Here's how I understand the issue of the key switch - if I'm off, I hope Joe or some of the other guys will chime in.

The start circuit and the "on" circuit in the key switch are distinctly separate. When the key is in the off position, the circuit going to the number 6 terminal grounds the output side of the power pack. When the key is in the "on" position it is not supposed to ground, but if the switch is defective, it does. By removing the wire at the number 6 terminal on the power pack, you eliminate the ground in a defective switch. Since the alternator (made up of the stator and the flywheel) will put out current as soon as the motor cranks, once this problem is eliminated, spark will be present on all three cylinders, if the power pack is good.

The start circuit in the switch merely serves to send voltage to the starter solenoid to engage it. Whether the "on" circuit is functioning properly or not is not a factor in the ability of the solenoid and starter to engage.

Okay, I think I understand. In that case, by leaving the key in the 'on' position and draining my battery, didn't I accidentally perform a very stupid test to determine the key switch is not defective? I will still do the switch test, in any case.

I noticed a small hairline crack in the casing of one of the ignition coils, so whatever else tests bad, looks like I'll be replacing them.

 

[jay_merrill]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

I don't think leaving it on does prove the key switch is good. When the key switch is on, the ground that I mentioned is supposed to be interrupted, but that is not the only thing going on.

Remember that the powerpack gets its voltage from the alternator directly. The black/yellow wire (#6) is a "ground/no-ground" circuit only. When the motor isn't running, what the key switch is doing with respect to this circuit is irrelevant because there is no voltage being delivered to the power pack.

On the other hand, there is a red wire feeding 12 VDC to the key switch from the alternator (via the rectifier) and the battery, which feeds other circuits when the key switch is in the "on" position. I believe that those circuits are the hot horn (no factor because it is an open circuit unless the temp sensor closes it), and the neutral solenoid. I think the neutral solenoid would engage, even though the motor won't actually shift to neutral for lack of hydraulic pressure, and complete a circuit to ground.

I think the bottom line is that you should just go ahead and do the test. Also bear in mind that the problem with the key switches when they go, is mechanical wear, so sometimes the problem is intermittant. I replaced my key switch before total failure just because I noticed intermittant problems. If you get into a rebuild program, you might want to do the same, unless the switch looks like it has been replaced already.

On all of this information, bear in mind that I offer it based upon studying the manual multiple times, and tinkering with my own motor. My local OMC/BRP dealer is also very good about giving me advice. But, the bottom line is that I am still a "backyard mechanic," so if anyone reading this has a different understanding, I will not be in the least bit offended if they correct me. In fact, I hope they do because I want to get to the point where I understand these motor thoroughly, and will gladly accept all the info I can get!


PS: If you have a tach installed, which also receives 12 VDC when the key switch is in the "on" position, I think you would have an additional ground.

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

jay_merrill, can't thank you enough for your help, man. Otherwise I'd still be waiting, frustrated and annoyed for the manual to show up in the mail, while these last days of boating season ticked away...

So I did a compression test, which came up with some really good numbers-- 145, 140, 140. I guess that means the old motor is worth fixin' up.

I did another test on spark to the plugs with the spark tester I bought just to make sure-- nothing.

So I tried the key switch test, removing the #6 wire and checking spark from all three coils when cranking-- nothing.

I did the Joe Reeves lightbulb test for the power pack, connected to each of the 3 coil connections on the pack & ground-- nothing. Here's the link to the forum I got that idea from if anybody's interested-- (I hope it's ok to post links from other forums):
http://www.marineengine.com/cgi-bin/discus/show.cgi?tpc=12478&post=35920

Then I tested the sensor coil with a meter. Manual said ohm readings should be 8.5 +/- 1, 8.5 was pretty much on the money. continuity test was also ok. Charge coil-- manual said 900 ohms +/- 30, I got 895.

The manual also says about ignition coils, "the coils can be checked with a conventional ignition analyzer, using ignition info given in 'Specifications' page 2-2." Is that where I'd need a DVA meter, or an oscope? I think I should probably replace the coils in any case, because of j_m's advice to replace it all, and because I have a crack in the #1 coil casing (see pic). That can't be ok, right?

So I'm feeling a little more optimistic about my motor-- compression is good, sensor and charge coils *seem* to be ok--that stator assembly probably costs a bit 'o $$. Also, I don't want to try to remove the flywheel and then reset the timing if I don't have to. Does it really take special tools to remove the flywheel like the manual says or can you improvise?

I'm hoping if I replace the power pack, ignition coils (and maybe the key switch just to be sure), I'll be back on the water. Does this sound like a good plan or am I forgetting to check something?

 

[jay_merrill]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

You can do an ohms test of the sensor coils to ground - one lead of the multimeter to ground, the other to each of the sensor coil leads, one at a time. The reading should be infinity.

Also, if you replace the coils, be careful not to pinch the hot horn to temp sensor wire, when you replace the center coil. If you look at your photo, it is the tan wire than is running to what looks lile a plug in the head. It is very easy to pinch that wire and tear the insulation, which will cause it to ground and make the horn sound.

PS: Watch for another post - I want to check something on my motor because Joe's light bulb test has me wondering if I am wrong about the #6 post to key switch circuit being a ground. I'm going to go put a meter on my motor with the key on to see if I get any voltage at the #6 terminal.

PS #2: OK - no voltage at the #6 terminal in the power pack, with the key switch on. I think that verifies my understanding that this circuit is about grounding the output side of the power pack, not providing voltage to it.

At this point, my opinion is that you have bad power pack.

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

SHE RUNS!!

You were right jay, it was the power pack. I didn't want to wait to get one I ordered online, so I found a store nearby that had one. Put it in and got spark! Put the muffs on and she fired right up!!

I do plan to get new coils too, and maybe a new ignition switch. Hey, I think I also read in another post that a weak battery can cause a power pack to fail. My battery has always held a charge really well, but maybe I need a battery with more cranking amps...anybody have any opinion on that?

Anyway, big thanks to everybody who helped me out, especially jay_merrill. If you ever get to this part of Michigan jay, stop by and beers are on me!

 

[jay_merrill]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

Glad to hear that it is running! Now go fishing! Don't worry about the beers, we wanna see fish pictures!

Your right about the battery issue - the minimum specs for this motor are (page 7-2 of OEM manual):

70 amp-hour, 2 minute cold cranking @ 300 amps discharge & zero degrees farenheit, 10 second voltage reading of 7.5 volts.

I have also been told by my local OMC/BRP dealer that a weak stator will eventually cause the power pack to go bad, as well.

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

Glad to hear that it is running! Now go fishing! Don't worry about the beers, we wanna see fish pictures!

Your right about the battery issue - the minimum specs for this motor are (page 7-2 of OEM manual):

70 amp-hour, 2 minute cold cranking @ 300 amps discharge & zero degrees farenheit, 10 second voltage reading of 7.5 volts.

I have also been told by my local OMC/BRP dealer that a weak stator will eventually cause the power pack to go bad, as well.

Yeah, I should check the voltage coming from the stator.

And see about my battery.

And check/replace the oil in the lower unit, make sure there's no water in there. Guy I bought the boat from said it should be checked/replaced 1/2 way thru the boating season, but I don't take her out every day.

And probably clean the carb. The old plugs were pretty fouled. I dialed back the lean/rich at slow speed dial. Does that seafoam stuff work? Hopefully I can get by with that for the next month and maybe take the carb apart this winter.

But for now I'm taking the rest of the night off. Think I'll crack a beer and drink to ya, jay...

...and as for going fishing, don't hold your breath for fish pics. My fishing skill/luck is so bad it's almost legendary. Maybe I'll open a post about that in the fishing forum

 

[mike64]

Re: Tow of shame!! 1972 Evinrude 65hp no spark

Tested out the motor couple more times over the weekend, continued to start up instantly and run fine on muffs. I want to do a couple more things before I take her back out on the water though, and I have a few more questions.

Going by jay_merrill's advice that once parts of the ignition system start to go, it's time to replace most/all of it-- I'm planning on replacing the coils which I don't think should be a problem for me. But is there a way to test that the stator is putting out adequate voltage? The stator assembly is basically the charge coil and sensor coil together, right? What voltage should they be putting out? The manual's way of testing is with a neon light tester with different load settings that's probably obsolete.

If I do replace the timer base and/or stator, how difficult is it to remove the flywheel? The manual mentions a couple special tools for that-- a flywheel puller and stop. Can conventional tools be used? Like for the stop, can you wedge a screwdriver or something to stop the flywheel moving so you can get the bolt off? And do you need a puller, or just a big wrench?

And when you remove the flywheel, you need to reset the timing. How difficult is that? Do you need the "piston stop" special tool or can you improvise that? (I guess a lot of this post is asking which special tools are actually needed, which are obsolete so you need something else, and which can you improvise with regular tools).

And as for the battery, jay_merrill posted the minimum specs for my motor: "70 amp-hour, 2 minute cold cranking @ 300 amps discharge & zero degrees farenheit, 10 second voltage reading of 7.5 volts.". My battery is a Stowaway 27DP-6. From what I could figure out on the internet, the "DP" stands for "Dual Purpose" or a cross between a deep cycle and starter. I don't know about the amp-hour rating, but it's supposed to crank 750 amps at 32 degrees F. Which would probably be 600 at 0 deg. F. which would be twice min. spec. Should I get a dedicated starter battery, despite the specs?

Sorry about all the detailed questions here. I thougth about breaking these up into a few new posts, but I decided these questions were still related to this post. The first power pack lasted 36 years, for all I know this one will last another 36, but I want to do everything I can to avoid another "TOW OF SHAME!!"