Spark Problem - 1982 Johnson 140hp

Hi all, newbie to the forum, newbie to outboard ownership and certainly newbie to outboard mechanic'ing...

I spent the day yesterday studying the forum and studying my new service manual...yesterday evening I delved into my motor just expecting to find a faulty power pack but now I'm stumped.

Motor: J140TLCN, 1982 Johnson 140hp

Bought the boat a few months ago - have used it about a dozen times - run great - very happy.

Took the family to the lake on Memorial day - launch - hammer down -and much lack of power. It would crank (albeit more difficult than in past) and rev up but when put in gear it had no power to get up. I put in a new set of plugs but that made no difference. I noticed when changing the plugs that the two plugs on the left bank (I believe they are cylinders 2 and 4) were pretty wet while the plugs in 1 & 3 were dry. I figured this might mean getting no fire on left side of engine.

Came home (still enjoyed day on the lake by the way), studied the forum, bought an inexpensive service manual, studied it and began work expecting to find a powerpack faulty.

Checked compression - 125psi on cyls 1&2, 115psi on cyls 3 & 4 (very good).

Made a spark tester with nails and wood (very cool)...getting good spark on cyls 1 & 3...not getting spark on cyls 2 & 4...cool - just as I expected.

Next I think - I should be able to swap the location of the 2 powerpacks and the faulty ignition should move over to cyls 1&3 - so I swapped them over. But then I was still getting spark on cyls 1 & 3 and no spark on cyls 2 & 4...????

So then I think that possibly it is two faulty coils....so I move the coils that were on cyls 2 & 4 over to cyls 1 & 3 (and vise versa). Then I check fire and still getting nice fire on cyls 1 & 3 and getting no fire on cyls 2 & 4....????

Then I went to bed very perplexed.

It seems like I have good compression, two functional powerpacks, 4 functional coils, good plugs and wires, but something is preventing fire on cyls 2 & 4.

I should also mention that when warming up the motor while still on the trailer the heat horn sounded off for a short while. It did go off after about a minute or so but the motor was pumping water the whole time out of the spit holes. It never came on the rest of the day (we idled out about 100 yards offshore and anchored there for the day).

I read in a post yesterday that that the horn could be an indication of a fuel restriction / fuel flow. I may need to revisit that possibility but when I discovered the lack of spark that is where my focus has been.

Any help would be most appreciated.

Many thanks - and fantastic forum.

Trey Monson
McKinney, TX

There are two sensors in the timer base under the flywheel. One sensor fires cylinders 1 & 3, the other sensor fires cylinders 2 & 4. Cylinders as viewed by standing in back of the boat, facing the spark plugs are as follows.

2.....1

4.....3

It appears that one sensor is not firing the port (left) bank. Check the rubber plug connectors leading from the timer base to the powerpack. The pins or sockets have a habit of becoming pushed back within the plugs which results is a poor or non existent connection.

Also the wires have been known to break away from the pins/sockets but would still stay in the end of the rubber plug. This gives the appearance of having a connection when it obviously does not. Check the connections and let us know what you find.

You could also compare with an ohm meter the sensor resistance between the starboard and port bank sensors..... should be the same.

I did try to measure the resistance of the stator on each side...I was measuring at the brown and brown/yellow wires at the connector that go up into the stator on each side (I think this is what you're calling the timer base). One side measured about 380 ohms and one side measured 0 (neither of these are within the specs that I've found). This seems really strange and I think I was doing it correctly. I analyzed the stator closely and did not see any significant cracks or apparent melting as noted in other posts.

Additionally, using spare wire and alligator clips I was able to connect the output from the stator on cyls 1&3 over to the powerpack of cyls 2&4 and I got fire on cyls 2&4.

So, this tells me that either the stator output on the port side is bad (and I assume the whole stator would be considered bad), or there is a faulty connection somewhere inside the connectors on the port side as you described in your previous post.

I was preparing to go purchase a new stator but I think I'll make another attempt at making sure I have good connections everywhere as you suggested. If it turns out that my connections are good and the output of the stator appears to be faulty on one side and good on the other - is it the stator that is bad or could it be the other part that is inside of the stator (under the flywheel) - I cannot recall the name of that part at the moment.

Sincere thanks for the post and information.

Trey

The "stator" is the large ring of coils under the flywheel. The Brown & Brown/Yellow wires provide approximately 300v AC to the powerpack. The yellow wires pertain to the charging system.

The smaller unit under the flywheel (the one that moves) is the "timer base", the wires whose color escapes me at the moment (blue, white, whatever). These are the wires that lead to the sensors I mentioned previously.

If you are absolutely sure that there is no resistance between the Brown & Brown/Yellow wire on one side of that stator (open circuit), especially if it is the side that has no spark, that would make it impossible for the stator to energize the related powerpack.

I got back to testing the resistance of the stator today...the side of the motor that is not firing is reading .126 ohms. the side that is firing is reading about .300 ohms.

I'm not the most familar with reading ohms - but do these numbers translate to 126 ohms and 300 ohms?

Either way I believe that the specs are such that both sides of the stator should provide somewhere about 500-600 ohms. Is this correct?

I'm pretty certain that I'm on the verge of ordering a new stator.

Thanks for the input.
Trey Monson

I'm not sure what I was reading before - but I'm confident that I've now determined that one side of the stator is reading 594 ohms of resistence and the other side (the side not producing a spark) is reading barely over 300 ohms. Considering that the specs are that each side should provide 500-600 ohms of resistence then is it my stator that is faulty. I'd appreciate any feedback as I believe I will order the part on Monday and would like to consider any other thoughts prior to the purchase.

Thanks,
Trey monson

Your readings indicates a faulty stator.

Thanks Joe for the reply. I'll order the part tomorrow and will let ya'll know whether it gets me running again. Great forum all!

I received the new stator and installed it yesterday. Out of curiousity I tested the resistance on the new part and it measured about 550 ohms on each side. I installed it and now have a nice pretty blue spark at all 4 cylinders. We're hoping to make a lake test this weekend and I'm confident that this problem is resolved. Many thanks to all of you for your input. Great forum.

Thanks,
Trey Monson

Glad to hear that everything worked out for you. Have a good boating season.