Help! no spark. '72 50hp johnson

[choretime]

ugh! new to boats and motors. this boat and motor were supposed to be ready to go fishn but its one thing after another! got motor to run great then put it in the lake and would not start, got home and had intermittend spark. saw both ign. coils had craks in them and got 2 new ones from napa, installed and still no spark. what do i check or FIX now? by the way this forum has helped me solve all the other issues that have appeared. Thanks for the past info and any new. donnie

 

[Basher]

Re: Help! no spark. '72 50hp johnson

choretime,

please post model #. Someone will be along to help.

Basher

 

[jay_merrill]

Re: Help! no spark. '72 50hp johnson

The best thing you can do for your own sanity is to buy a factory service manual. Troubleshooting your motor can be done from advice but its just much easier to go through the systematic steps in the manual. You can get one here at iboats.

I believe that you have a magneto CD ignition system, similar to that in the 3 cylinder 1972 65hp Johnson. If you are not getting spark at all, the most common reasons are a bad ignition switch, a bad powerpack or a bad stator. You could have a bad timer base (both sensors bad), but it is more common for this item to cause problems with less than all of the cylinders.

BTW, one other common issue with these motors is exhaust leakage from the lower unit into the cowl via the port where the gearshift wires run into the exhaust tower. This really has nothing to do with your current problem, but is worth mentioning because it will degrade engine performance if it is present. To fix, remove the ring cowling around the lower cowl/exhaust tower, and seal with heat resistant silicon.

 

[choretime]

Re: Help! no spark. '72 50hp johnson

thanx ordered a serv. manual and should be here in a few ill chk that wire hole and seal if needed. Having fishn withdrawls

 

[choretime]

Re: Help! no spark. '72 50hp johnson

50 esl72c model # thanks basher!

 

[choretime]

Re: Help! no spark. '72 50hp johnson

jay i got the serv. manual. what a great tool! ran tests on stator - no volts- ohms were 840 (within range). chkd base - ohms- book says 15 +-5 my reading was 63! pulled flywheel and saw that there was arcing on crank shaft. so does this mean that both stator and base r shot? tests on ign. were neg. so that seems good. power pack seemed to be in spec.

 

[jay_merrill]

Re: Help! no spark. '72 50hp johnson

Did you get bad readings on both of the sensors in the timer base? If so, that would be an explanation for no spark at all.

Also, any idea where the arcing was coming from? That sounds more like a stator issue to me. I don't know what sort of voltage the 50hp puts out but the 65hp is 300 VAC from the stator, which is then converted to DC in the power pack. The sensor system is low voltage, so I'm thinking that an obvious arcing issue is more likely to be from a high voltage source. All of this would also, of course, be a pretty good reason to be having major ignition issues.

While we all must address budget issues in our boating hobby, this information would be pointing me in the direction of just replacing all of the ignition components. I guess I would start with the stator and timer base and then see if the motor wanted to run. With all of that other stuff going on though, your power pack might be bad too.

 

[choretime]

Re: Help! no spark. '72 50hp johnson

yes both sensors were bad. and the arc ing lines up with the sensors. one other thing i noted was that one of the charge coils had leaked a gel or goo out of it so my geuss is that it was under some serius heat or voltage. if you feel that the best course of action would be to replace the stator,timer base and sensors where is the cheapest place to get the parts,(napa,iboats,my johnyrude dealer?). money is a little tight so what order should i do them in?

 

[jay_merrill]

Re: Help! no spark. '72 50hp johnson

The stock stators do get pretty hot and some people recommend replacing them just for that reason. I bought my ignition parts from a couple of sources, after shopping for price. Even though I try to support my local dealer, I don't recommend buying directly from OMC/BRP because their pricing is very high, and rumour has it that the parts are rebranded aftermarket parts anyway. I did make an exception on the coils (I replaced all three of mine) because they are the OMC part and I like the way they are made. They also aren't all that expensive. Be aware, however, that while I was able to buy three of the stock OMC coils, BRP appears to be selling aftermarket coils for the older motors too, so there may not be any value in paying a higher price at the dealer.

Sierra and CDI are your best bet and there any many retailers selling their parts. Some say CDI products are better, and I recommend that you surf the net for the best price, taking reseller reputation, longevity and credit card security into account. IBoats may be a source, as well as others.

If you have two bad sensors and a bad charge coil, you are going to have to replace both units. Unfortunately, they are also the two most expensive parts in the ignition system. The only alternative that I can offer you is to replace the sensors in the old timer base, if you can find a pair that are within spec. These sensors are no longer made and the new timer bases are sealed units, so finding serviceable sensors for the old, metal timer bases is difficult.

 

[choretime]

Re: Help! no spark. '72 50hp johnson

thanks for the help and advice. i looked on the web and found a website that was 50 bucks cheaper than iboats. napa didnt even carry them. ordered the big 3 STATOR,TIME BASE,POWER PACK. just bite the bullet and save on shipping,(break it up into a couple of payments on my discover card) ill let ya know sometime next week if she purrs to life. oooohhhh one last thing the arc pitting , should i file or emery cloth to smooth it out.

 

[jay_merrill]

Re: Help! no spark. '72 50hp johnson

I think you did the right thing. I went through this with my 1972 Johnson 65hp and tried to get by with some used parts for a little while. I had purchased a complete ignition assembly from another, J65 on EBay, and scavaged some parts off of it to use on the motor that I had in use. The used powerpack worked for some time just fine, as did a coil and a timer base, but eventually things started breaking down.

I do a little SAR here and there and ended up with a hunk of junk in one of my carbs (obviously not related) and the ignition problems at the same time, while trying to find someone. I made it back to the launch OK with my kicker but it sort of "inhaled" not to be able to complete the mission. I also tend to be out in the bayou sometimes late at night, for both SAR missions and personal boating, so I just decided to replace everything. The money tends to be a bit much all at once, but its still a heck of a lot cheaper than buying a new motor and, as long as the rest of the motor is in good shape, restores the kind of reliability that gives confidence. Its also sort of fun to go rescue someone in the middle of the night, who is in a $40,000 boat, with my 36 year old motor!

Let us know how it all works out - I think you should be back out on the water soon!

 

[choretime]

Re: Help! no spark. '72 50hp johnson

sorry its taken sooo long but there was alot of baling and spraying to do. its rainy today and i had time to install all the parts. checked all the readings on my tester and they looked good so i put the muffs on and she fired right up! I let it run on a fast idle for about 12 - 15 minutes. let it sit for a minute or two and then restarted and ran it for another ten. hope to take it for its madien voyage soon and then after i get home do a decarb on it. thanks jay for your help. by the way you doing the s & r thing is way cool, i tip my hat to ya.