Johnson 115 No spark on one cylinder

[adelainey]

Hi everyone.

I have a 1993 Johnson 115hp 2 stroke (model VJ115TLETS) that isn't firing on one cylinder. Every time I remove the spark plug it's fouled really bad. I have replaced the plugs, coil and leads but still no spark. I am going to swap the power pack today and see if that helps. I have downloaded the pdfs from CDI on troubleshooting the stator and timing base. They are well over $300 each at the local Johnson supplier so I want to be absolutely sure that they are faulty before replacing. I am just wondering if there is anything else to test/troubleshoot besides these.

The motor idles real smooth at about 1000 rpm. But at WOT I am only hitting about 4800 RPM and not getting any real speed. This motor is on a 24' pontoon and I am not expecting high speeds, but with two people in the boat I should be getting more than 10-12MPH. It also hesitates while giving it any kind of throttle. So I am assuming that being short a cylinder would cause this.

Any help is appreciated.

 

[racerone]

Have you confirmed that the bad cylinder has no spark or is the cylinder dead , as in poor compression or no fuel ?-----Compression test might be a good idea.

 

[Bob_VT]

Okay here is how to approach that............. You can check the compression but that's not the cause of the fouled plug. Take off two of the ignition coils and swap them. See if the problem follows the coil or remains in that cylinder. If the problem moves with the coil then you need a new coil which is about a 5 minute job to replace. A coil is about $30 here and I favor the CDI brands http://www.iboats.com/mall/partfind...d_poid=334774&gd_row=247&session_id=886051534

Now IF the problem remains with the same cylinder get a timing light and attach it to that cylinder and watch the light flash.........now move it to a good cylinder and watch it......... if the flases are different then you might need a power pack...... available here for about $111 http://www.iboats.com/mall/partfind...d_poid=334574&gd_row=321&session_id=886051534

Once it is running on all 4 cylinders you will absolutely know it.

Been there...... done that and yes it is frustrating.

 

[racerone]

If there was no spark then a new plug as mentioned would stay clean and porecelain would stay white !!!!!

 

[adelainey]

Thanks for all the responses. I will be doing a compression test as soon as I get out to the lake tonight. Then I will try the coil swap and check the timing. Good ideas

 

[gonefishin485]

along with that compression test i would do a spark test to it, if you dont have a spark tester, pull your plug out and hold it against the block and spin the motor over but dont try to start it, just spin it to see if it fires. it should jump a hot blue spark and youll heard a crisp snap. also if you dont have a compression tester, a cheap redneck trick i use is to remove the spark plug, put your thumb over the plug hole and spin the motor over. if it has go to decent compression, it will pop your thumb off the hole or atleast blow air past your thumb. if you can hold your thumb over it and you get nothing, you got low to no compression on that cylinder.

if you have good compression and good spark, id look at the carbs. i have an 85 v4 that acted like it had a dead cylinder, had good spark and good compression but the idle jets and part of the main jet was clogged up on the carb feeding that cylinder.

 

[adelainey]

Thanks for all the responses. I will be doing a compression test as soon as I get out to the lake tonight. Then I will try the coil swap and check the timing. Good ideas

 

[adelainey]

Well I did a compression test. 102 on the one side on both cylinders. 87 and 0 on the other 2. The piston moves basically freely in the cylinder walls. So dead cylinder. Guess a rebuild is in order. Think it might cost more than the motor is worth

 

[racerone]

This is very common on these motors.---Just bought a 1995 model that looks to be 2 years old.------One bad cylinder.--Easy to fix to make it a reliable runner again.

 

[racerone]

Simple " old time " trouble shooting is all it takes.---Seems that is becoming a lost art !

 

[adelainey]

Racerone. If this was your motor what would be your next course of action?

 

[racerone]

I would fix it with WISECO pistons and have a good reliable runner for years to come.----I am not a fan of complex 4 strokes and computer controlled motors.---------Thes older V-4 use a bit more fuel but are very reliable when properly looked after and maintained.

 

[gonefishin485]

not trying to hi jack the thread, but what causes one cylinder to lose compression like that? i see motors on craigslist all the time with one bad cylinder, im just curios as to how it happens.

 

[Bosunsmate]

not trying to hi jack the thread, but what causes one cylinder to lose compression like that? i see motors on craigslist all the time with one bad cylinder, im just curios as to how it happens.

1)Stuck thermostat, failed water deflectors, failing water pump,
2)-running lean

 

[gonefishin485]

interesting, i was figuring maybe a carb failure, cylinder ran dry and destroyed the rings.

 

[Bosunsmate]

interesting, i was figuring maybe a carb failure, cylinder ran dry and destroyed the rings.

yes thats running lean.
but i find with running lean you normally notice it not running well and the motor hesitates a lot whereas in a overheat i find it happens fast before people hear the buzzer or the overheat alarms arent working.
if i havent run a motor in a while i normally kill the spark and turn it over a few turns then i remove the plugs and check that they a all similar in wettness so i know none are running lean.
Takes me all of five minutes in a 4 cyl motor and can save a big rebuild

 

[racerone]

The top ring has a taper.---As ring wears the side clearance increases.--At full throttle 5500 RPM the ring is bouncing around in the groove.--The ring breaks.-----No mystery at all !!

 

[adelainey]

You are all on the right track. I have only had the boat a couple months and had it in the water about 4 times. The overheat alaram started going off last week. I just replaced the water pump and the thermostats. Thermostats were completely clogged as were the two water inlet hoses that lead into each head. So I am sure that would cause issues and be part of the cylinder failure. Don't think it was running lean though. Lots of blue smoke while idling. Expensive lesson learned. There is a place in Winnipeg that rebuilds power heads or will ship reman power heads. I have heard from others that's it's around $1600. That is the closest place to me that I can get the powerhead from. Local boat shop would want well over $3000 for a rebuild.

 

[racerone]

At $100/ hr most shops are reluctant to repair these things , especially in the busy season.-----------Where is your location ?-------I have well over a dozen of these motors for parts and rebuilding.--Always the same problems with them.

 

[adelainey]

In Canada. Saskatoon, Saskatchewan. Would any of these motors have a good power head? What would you want for one?