72 Johnson 50 No spark DOA!

I have a 1972 50hp Johnson Anniv Ed with very low hours on it and it has run great up until today. The only problem I have had was gunked up carbs, which I rebuilt a couple years ago. I started with the muffs 1 month ago and it fired first crank after sitting all winter(WI). Today I took my wife and son to go fishing on a local lake and all it would do is crank over with no sign of firing. Fuel was getting to the plugs and carbs. I bought a fresh tank of fuel filling my other empty tank, no luck. I pulled a plug and grounded it and there was no spark. Usually it puffs exhaust if it takes a few revs to start, but no exhaust, just fuel smell and some leaking down into water.

Anyway, I have had issues with the muffs and starting and cranking long, but I wrote it off to an old battery and after trying later it started. I never had it die at a lake, but only use it a couple times a year. I did replace one coil that was cracked but working fine, and checked the stator and it has no leaks and looks like new. I'm wondering if it is the power pack like yours, and how do you tell.

I would describe my issue as a no spark intermittentlyin the past and now there is no spark after several attempts.

Power pack? How do you tell? Other electrical parts?

Thanks,

Steve

Re: 72 Johnson 50 No spark DOA!

Go to the FAQ and follow the steps provided by JB in the thread "Outboard Wont Start" If in fact you find that it complete spark failure, follow the testing provided by the CDI Troubleshooting Guide below.

NO SPARK ON EITHER CYLINDER:

1. Disconnect the black yellow stop wire and retest. If the engine's ignition has spark, the stop circuit has a fault-check the key switch, harness and shift switch.

2. Check the stator resistance. You should read approximately 500 ohms from the brown wire to engine ground.

3. Check the DVA output from the stator. You should have a reading of at least 150V or more from the brown wire to engine ground (while connected to the pack).

4. Check the timer base?s resistance from the black/white wire to the white/black wire. Reading should be 10-20 ohms (or 30-40 ohms for CDI Electronics 133-0875K1). Note: The original factory specifications was 8-14 ohms, this was changed around the mid 1970?s in response to the change in SCR?s triggering requirements.

5. Check the DVA output from the timer base. A reading of at least 0.5V or more from the black/white wire to the white/black (while connected to the pack) is needed to fire the pack. If the output is low, you may try to reset the air gap between the timer base sensor and the triggering magnet.
a. Loosen the two mounting screws on the sensor and the nut located in the epoxy on the outside of the heat shield of the timer base.
b. Slide the sensor in toward the crankshaft approximately 0.005? at a time.
c. Coat the face of the sensor with machinists bluing or equivalent.
d. Install the flywheel according to the service manual and crank the engine over.
e. Remove the flywheel and check to see if the trigging magnet struck the sensor face.
f. If the ignition fired, finger tight the nut on the outside of the heat shield and coat it with RTV.
g. If still no fire, slide the sensor in another 0.005? and repeat steps c through f.

6. Check the DVA voltage on each trigger wire to engine ground. You should have a reading of at least 150V or more from the black/white wire and the white/black wire to engine ground (while connected to the pack). If the reading is low, disconnect the trigger wires from the pack and recheck the terminals on the pack. If the voltage jumps up to an acceptable reading, the timer base may have a problem in it?s internal wiring (A thin spot in the insulation on one wire).

7. Check the cranking RPM. A cranking speed of less than 250-RPM will not allow the system to spark properly.

Re: 72 Johnson 50 No spark DOA!

Thanks High Trim,

I had it down to no spark at the lauch pier, but will verify out of water today and move on to the "no spark on either cylinder" check procedure if no spark on either cyl verified. I will report back on what I find. Thanks for the great troubleshooting resource(s).

Steve 72 Johnson 50hp Anniv Ed, 14' Glass Lund CCP

Re: 72 Johnson 50 No spark DOA!

Also, keep in mind this is an intermittent problem. It starts fine most of the time but there are times where all it does is crank with no spark. This is just the first time in the water it would not start. I would always get it to start after charging the batter, cleaning terminals, etc.. thinking that might have been the issue. But now I'm seeing a pattern of the spark just not being there. That is why I'm asking for what might be causing these symptoms. I may be troubleshooting and everything will be fine. Then next time, no spark. Any clues on my intermittent symptoms in case the spark magically comes back? This is a very clean motor with low hours but use once or twice per year in Wisconsin freshwater.

Steve

Re: 72 Johnson 50 No spark DOA!

If I had to guess I would bet on your stop circuit having an intermittent fault OR you are not getting the proper RPM to have the system spark properly. If disconnecting the black/yellow wire produces spark in a no spark situation, you will have it narrowed down. Otherwise, I would voltage drop test to isolate a section of faulty wiring or poor connection.

Re: 72 Johnson 50 No spark DOA!

OK, I verified no spark out of water on both cylinders. I fully charged my battery (new last year) and used a inductive pickup timing light that I know worked on the engine when I had checked the timing 2 years ago. Anyway, I then moved on to step one on the "no spark on either cylinder" troubleshooting list. I disconnected the black/yellow stop wire from the top right powerpack connection screw, cranked the engine and again no spark either cylinder. I then replaced the black/yellow wire and checked the other powerpack screws finding the top coil wire screw maybe a half turn loose but still plenty of contact. I replaced the power pack cover and prepared to move to step 2. I cranked the motor just to make sure I didn't mess something up and it fired right up. (don't worry, muffs on with water running as always when cranking). I shut it down and started it at least 2 more times barely touching the key to the start position. I then let it run out of fuel, since I didn't have the tank hooked up.

Anyway, I still didn't find out what was wrong, yet the motor fired right up as it usually does (except when it just cranks?). The only items I could have affected were the power pack (vibration/contact) or tightening the screw to the upper coil (although I would still expect the lower coil to fire).

It seems like I have an intermittent issue here and it may be with the power pack since that is what I was affecting in step one. Does anyone have any suggestions at this point? I can keep going down the troubleshooting list, but the motor now runs?

Steve 72 J 50

Re: 72 Johnson 50 No spark DOA!

Im going to go on what you stated, "Anyway, I still didn't find out what was wrong, yet the motor fired right up as it usually does (except when it just cranks?). "

You may have faulty wiring or a poor connection from the battery to the solenoid, or from the solenoid to the starter, or from the battery to ground. Try the following.

First set your DVM to the 20 Volt scale

Put your POS voltmeter lead on the battery POS terminal and the voltmeter NEG lead on the large incoming solenoid/battery terminal post and give her juice. If the meter reads more than .3 volts, the battery cable is bad, corroded or you have a faulty connection (loose).

Next, connect the POS lead to the incoming large solenoid post and the NEG lead to the outgoing large solenoid post while giving her juice. If the voltmeter reads greater than .2 volts, the solenoid is bad, corroded or has a faulty connection.

Next, connect the POS lead to the outgoing large solenoid post and the negative voltmeter lead to the starter positive post and give her juice. A reading of over .2 volts indicates faulty wiring between the solenoid and the starter.

Finally, connect the NEG lead to the NEG battery post and the POS lead to the engine block and crank the engine. A reading greater than .3 volts indicates a faulty negative cable, corrosion or a faulty connection.

Re: 72 Johnson 50 No spark DOA!

I've been sitting back on this thread because, while I know the 1972 Johnson 65hp well, this motor is likely to be somewhat different. That said, enough information is coming to light to give me a few ideas.

This problem strikes me as being either wiring related, or start switch related. The fact that you ended up with consistent spark again, after manipulating wires on the power pack, makes the wiring suspect. I think I would put the motor on muffs again, run it, and use some insulated pliers to gently move all of the wiring on the starboard side off the motor around. Move the yellow plug too. If you get no noticeable problems, "jiggle" the key switch, without turning it to the off position, to see if the problem might be in the switch.

If none of these things reveal an obvious problem, try cleaning all of the wire connections - ring terminals and contact points. I would do them one at a time, so that you don't forget what goes where.

PS: Edited this because I had a flaw in logic in regard to the ground circuit to the start switch. If you read the previous comment about the terminal coonection being the potential problem, please ignore.

Re: 72 Johnson 50 No spark DOA!

Thanks for the ideas HT and Jay,

Here's where I'm at right now. I On the "No spark either cylinder" list #1 black/yellow wire disconnect, no spark also with wire disconnected. #2 The resistance reads 860 Ohms from the brown wire to engine ground instead of the 500 Ohms it should red (bad Stator?) I don't have a DVA so I cant do 3&5 yet but I checked #4 and get 17.8 Ohms so that's O'K. The cheapest DVA I found is $65 plus $12 shipping, are there any less expensive options?

HT, sorry about the bad definition of the current status but let me try to accurately describe it. The engine either has spark or does not. Ususally it does and starts right up and runs great. Once in a while it does not have spark and just turns over and won't start. It turns over very fast so I will say it easily exceeds the 250rpm minimum for spark generation. Another issue I have on/off dying of the motor on the water which I attributed to lack of fuel because I pumped the fuel bulb and it seemed to work, but another time it didn't and later just went away. The motor didn't die, but just dropped way down in speed and speeds back up again (this may be related to no spark). Right now the engine fires right up and runs again, at the dock the other day it just kept turning over with no spark.

I am going to check the battery wiring today per HT and clean up and check the connections(most have already been checked but I will make sure). Since Check list item #2 reading is 860 VS optimal 500 Ohms I would like to know what that indicates since the trouble shooting list does not say.

Thanks,

Steve 72 J 50

Re: 72 Johnson 50 No spark DOA!

I didn't mention this before because I didn't want to sound like I was questioning the generic troubleshooting list provided earlier, but I'm not sure your stator should show 500 ohms on the ohms test. For the 1972 65hp motor, the value that you are looking for is 900 ohms, plus or minus 30 ohms. At this point, I really think you need to get your hands on a service manual for your motor.

Also, my bet is that the ohms test for the timer base sensors should be 8.5 ohms, plus or minus 1 ohm - not the 10 - 20 ohm value detailed in the generic troubleshooting guide. I say this because that's what the correct value is for the 65hp motor, and I think that OMC most likely used the same sensors on the 50hp engine. The sensors can also be tested to ground - you should get a reading of infinity.

BTW - see the comment in the notes that the values were 8 - 14 ohms until the mid 70s. Your motor is an early 70s motor, so it would be among the lower value motors.

The fact that removing the black/yellow wire made no difference tells me that the key switch may not be your problem. What this circuit does is to ground the output side of the power pack (hence the mistake in my logic referred to above), when the key is in the off position. When the key switches go bad, the ground remains when the key is turned to the "on" or "run" position - which is why you disconnect the circuit to test the switch .. no connection, no ground, regardless of what is going on in the switch.

The business about the motor slowing down and then coming back to life could be one of the two cylinders cutting out. One way to confirm this is to rig up an inductive timing light in a way that you can watch it while underway. What I do is to tape the trigger shut, hook up the battery connections to power the light, snap the sensor onto one of the spark plug wires, and go for a run in the boat. If that particular cylinder is misfiring or cutting out completely, the timing light will flicker irregularly or will stop flickering entirely. Once one cylinder has been tested, you simply come to a stop, shut the motor down, and move the sensor to another spark plug wire, to repeat the test. Please do not try to move the sensor with the motor running! That's a good way to lose a finger in the flywheel, get zapped, or fall out of the boat!

If I were sure that both your cylinders were always losing ignition, I would be inclined to say that you have a bad power pack. That said, I'm not sure that you aren't getting loss of ignition in one on occassion, which might suggest timer base problems.

My advice at this point is to get that service manual, so that you can test the sensors and the charge coils in the stator properly. Until you know for sure what values you should be looking for, you are really shooting in the dark.

Re: 72 Johnson 50 No spark DOA!

Here's where I'm at now:

I tried to start the motor today just to get a baseline of where I'M at and it would only crank ( on a fully charged very healthy battery on the muffs). I checked for spark and found none on both cylinders with the inductive timing light. I then proceeded to clean all the connections including grounds, terminals, also checking wire continuity. The connections were amazingly clean and I brushed them up anyway. All wires were good from point A-B even when wiggling using a probe tester. This is a really clean low hours well kept motor, but I went through it to make sure. At each step along the way I cranked it over and no fire. My feet got pretty wet though from the muffs.

Anyway, I never did get it to fire today. It cranks over fine with no spark, and plenty of rpms to generate a spark if it could. Plenty of fuel, as the plugs are all wet (with fresh fuel that worked yesterday). I don't have a DVA so I can't check the specs that require one, but since steps 1, 2 and 4 from the trouble shooting guide are withing specification and check O'K, where should I go next?

I might add that the boat and motor are in excellent condition having been well cared for and very seldom used, so I am willing to put more $$ than some might think it's worth into making it right. Since it would cost a lot more to buy something new to replace it and I only use it 5-7 days/year it makes sense to me to keep it going.

Steve 72 J50

Re: 72 Johnson 50 No spark DOA!

You could always try this test by Joe Reeves on the Power Pack

(Battery Capacitance Dischage Powerpack Test)
Various OMC Engines - 1968 to 1972)
(J. Reeves)

Purchase a small 12v bulb at your local automotive parts store (the 12v bulb is to look like a flashlight bulb, not a headlight bulb). Solder two wires to that bulb, one to the side of the bulb (ground), and the other to the positive point. You might use a bulb of a somewhat lower voltage to obtain a brighter glow... just a suggestion.

Remove the spark plugs. With the key in the on position, make sure that you have 12v going to the pack at the terminal block (purple wire). Now, connect the ground wire from the bulb to any powerhead ground. Connect the wire from the positive point of that bulb to the powerpack wire that is connected to the coil wire on the terminal board (blue wire).

Crank the engine and observe that bulb closely (CLOSELY!). If that bulb glows even the slightest bit, the powerpack is okay. It may be a very dim glow... just so it glows! If it doesn't glow, the pack has failed.

Keep in mind, that type powerpack (Battery Capacitance Discharge) demands a top notch battery of at least 70 amp hours. Any less will, in time, cause powerpack failure.

Re: 72 Johnson 50 No spark DOA!

I have had problems with my 73 50 hp. Almost exactly like yours. I thought I was reading about my own motor for a second.
I have a power pack I can send you if you want to try it. I ask you to send me shipping costs and if it fixes your problem, send me 25 bucks for it. If it doesn't, send it back.
The power pack is used but it works. I have a brand new one installed on my boat and a brand new one for a spare so I really don't need this one.I almost guarantee that you do. I've been at the exact same spot.
I have a good stator and a couple of coils and a timer base if you find you may need some parts in that area also.
Let me know at fillupd@yahoo.com

Re: 72 Johnson 50 No spark DOA!

Fillup - that is a really nice offer and a case in point on why this is such a great community of people.

Rebmo, I went through some similar problems with my motor at one point. Like yours, it was a very low hour motor for its age so I felt OK about putting some money in it. I ended up replacing everything in the ignition system with a combination of OEM parts (coils) and CDI parts, with the exception of the stator. The motor has been rock solid ever since.

Re: 72 Johnson 50 No spark DOA!

Using the Powerpack test method that HT posted, the power pack appears to be dead on the output side. There is power to the pack, Very healthy battery, but no spark to either plug, no flicker on the 12v light bulb when attached to either coil output on the PP. At this point I am assuming the Powerpack is bad.

Replacement options for Powerpack:
1) OMC Johnson original new, rev limiter? (expensive, hard to find)
2) CMC Aftermarket cheaper than OEM, no rev limiter.
3) Sierra Aftermarket (least expensive, does not mention rev limiter
4) Used on from member of group, cheapest, getting back to me on used/new spare, past issues, etc..

What are the recommendations on the above assuming #4 is not 100%. Are the aftermarkets OK? Does the OEM have a Rev limiter and is it necessary?

What's the best way to go for reliability? I want to do it right since I will be keeping this boat/motor for a long time into the future and reliability overrules cost.

Steve J50 1972

Re: 72 Johnson 50 No spark DOA!

Also,

Regarding the Powerpack,

Is the original P/N 384986 OMC more desireable than the OMC replacement P/N (don't have at my laptop)?

Steve

Re: 72 Johnson 50 No spark DOA!

CDI Electronics makes one for your motor -the part number is 113-1397. I don't think it has a rev limiter in it They can be purchased on various websites & I have seen them for about $75.00.

Re: 72 Johnson 50 No spark DOA!

rebmo check your Private Messages....

edit that, cant seem to send private messages at this time for some reason

Re: 72 Johnson 50 No spark DOA!

After installing a good OMC powerpack2 I received from FillupD the engine still did not start and had no spark either cylinder as measured with my timing light. I then re-checked the black/yellow wire removing it from the powerpack, no start/spark. I then closed up the powerpack and checked the wiring connections and found the fuel supply to be on the weak side and fixed that by switching tanks and snugging up the fuel pump cover It then started and ran great, and started a few more times with just a click of the starter. I also verified the timing light spark check and got a solid flash off both plug wires with the inductive pickup. Even though I didn't have spark, I thought the fuel issue may have been a factor (optimistic foolishness). I went back out a while later and no start, spark.

After sleeping on it, it still seems like a wiring problem from the key switch. It dawned on me that the starts occurred after RE-connecting the black/yellow wire from the powerpack. So I went out this morning and tried to start it and it just turned over no spark. I then disconnected the black/yellow wire from the powerpack and tried to start it and still no start/spark. Then, I reconnected the black/yellow wire to the powerpack and it fired right up?

OK is this a starter switch problem? This does not match the logic of the troubleshooting, which does not explain why it would start when re-connected? It does seem to start repeatedly for a while after reconnecting the black/yellow but later will not start and no spark again.
At least I'm getting somewhere, but can't figure out what would cause this?

Steve 72 50hp Johnson

Re: 72 Johnson 50 No spark DOA!

That sounds weird, I feel for you. How about testing the continuity of the black/yellow wire from the switch to the power pack, when you have no spark.

When in a no spark situation, when everything is hooked up normally, unhook the plug and jump it, try the spark test then. do you have spark when the red plug is disconnected?

How about running a wire from your switch to the power pack and replace the black/yellow wire to see if that wire may be bad. You can just run a temporary wire to test it.

When you do not have spark, jump #4 to the engine ground and and crank it. Check to determine if maybe a ground is the problem. Have someone crank it and then jump the # 4 on the power pack. It may sound funny but mine did that. I found it when I had someone cranking, and on a whim, I had the meter on the engine ground and when I touched # 4 it cranked up and started. Scared the spark out of me. I let go of # 4 and it died.
If I can think o anything I'll let you know. Good Luck!