Stumped on 1975 115 Johnson

[crb478]

I have a 1975 Johnson 115 that has been running good until the last two trips out. On both trips it started normally and I took off and ran it up to WOT at about 5400 rpm. I throttled back to turn around and the motor died. On the first trip it cranked again and I limped back home. I took the lower carb off and found the float clip had come loose again so I put it back on and squeezed it tight to the needle. On the second trip it would not crank back. It was acting like it was only firing on two cylinders, but would not crank. I had to get towed back in, and loaded the boat on a trailer. When I got home it ran rough like it was running on two cylinders and would die. I suspected clip again, but when I removed the bottom carb there was fuel in it and the clip was still in place. I then took off the top carb and it was also correct. I replaced the carbs and ran out of time so I left it for the day.

Today about 5 days later I pumped the bulb to get gas to the carbs and cranked the motor over. It fired and ran rough for about 20 seconds and then smoothed out and ran normally. It was on muffs and was idling at about 1000 rpm. I had suspected a spark issue, but all four cylinders had good spark. Compession is between 110 and 120 for all four. Gas is fresh and bulb is staying hard. I have added a tell tail and it is pumping normally. The water from it did feel hotter to me when the motor was running bad, but that cold be my imagionation. The heads did not feel excessively hot, but were pretty warm after the wot runs. The carbs have recently been cleaned and still look great.

I really do not trust things that fix themselves so before I put the boat back in I am trying to get my kicker running again. Does anyone have any thoughts as to what might be causing the trouble? Any suggestions on what to check?

 

[Bifflefan]

Re: Stumped on 1975 115 Johnson

I doubt that it fixed it self...wish they did tho.
I do agree with the sprk tho, you may have something that is getting hot and shutting off. then when it cools it works again.

 

[Daviet]

Re: Stumped on 1975 115 Johnson

This sounds like one of those problems that will have to be checked at the time of failure. Take your spark checker with you, run it till it misses and check spark.

 

[crb478]

Re: Stumped on 1975 115 Johnson

Update on problem

I finally had time to take the boat out today to test it out again. I had cranked it in the driveway on muffs and it cranked and ran fine. I recently got my kicker motor back together and running so I was condfident that I could get back.

I put the boat in the water at the ramp and cranked it up, I then went to a dock about 1/2 mile away and tied the boat up so I could set the high and low speed needles on the kicker. I finished that and cranked the main motor again and opened it up for the first time as soon as I got out of the no wake zone. The motor took off as normal for about 1/2 mile and then the motor just died. It got up to about 5400 rpm before it died. It would not crank back so I fired up the kicker and headed for the boat ramp. I put the boat on the trailer and towed it about 1 mile home.

When I got home the motor was still warm and I used an inductive timing light to verify that I did not have any spark on any cylinders. Every now and then I would get a slow spark until it finally did not spark anymore. I have two batteries so the motor was spinning over fast enough. I also had no spark with the plugs out.

I checked the stator resistance from the brown to the brown/yellow wire and got 658 oms, higher than the 400-600 listed as acceptable. I do not have a DVA adapter, but I have a max button on my multi meter and I got 95 Volts instead of the required 150+ volts.

I then checked theTimer base resistance between sensor wires 1 and 3, then 2 and 4. The reading is supposed to be 10-20 oms. I got 8 oms on both.

I now need to get the flywheel off so I will be going to the store to get a socket and some bolts. I feel that the stator is probably shot, but does any one have an opinion on the timer base? Will the stator being out effect the readings for the timer base. I really would like to only put it together once, but those pieces are both expensive so I do not want to replace anything that is still working. Thanks for any help or ideas.

 

[iwombat]

Re: Stumped on 1975 115 Johnson

Before you do all that. Check and clean the ground straps on the coil mount bracket. There should be one strap for each side. The connectors should be shiny clean. It's a common (no pun intended) problem on those coil brackets.

 

[crb478]

Re: Stumped on 1975 115 Johnson

Should have mentioned that I had already checked and recleaned the grounds. I actually added grounds to the motor before just to try to avoid grounding issues.

Right now I have some used parts that I bought on the cheap just in case. They were all advertised as comming from running motors. The only problem is that one of the stators ohms out at 816 and the other one is 619. That makes all three stators outside the 400-600 range.

Two of the three timer bases show ohm readings of 8 or 8.1 on the 1 and 3, and the 3 and 4 sensor wires. The third is 8 on the 2 and 4, but has no reading on the 1 and 3.

I think my ohm meter is accurate, but those results sure make you second guess it.

Hopefully I will get to work on it some tomorrow.

 

[iwombat]

Re: Stumped on 1975 115 Johnson

Y'know you might also want to check your kill circuit in the ignition. This problem sure sounds like a bad switch, bad ground, or shorted kill wire to me.

 

[SparkieBoat]

Re: Stumped on 1975 115 Johnson

i agree with Wombat..it was my first thought when I read your original post..Check kill switch and all connections...also I check my spark with a $5 spark tester from my local auto parts store..not sure how a timing light will accurately test spark. Does that motor have 2 power packs or one..usually if I lose all my spark or lose it on one bank..I check kill switch then all wire connections, then the power pack.

 

[crb478]

Re: Stumped on 1975 115 Johnson

I will check the kill switch again, I check it a while back, but it could have been just starting to act up. Sparkie the inductive timing light fastens over the plug wires and flashes when the spark is sent to the plug. I will not tell you how strong the spark is, only that it is sending spark and of course when. Hopefully it will not rain me out this afternoon and I can get something done. I hate intermittent problems! Thanks for all the ideas

 

[crb478]

Re: Stumped on 1975 115 Johnson

Going back down my check list the first thing that I did was to disconnect the black and yellow wire to test the kill circuit. I went ahead and popped off the flywheel, mainly because I had never had it off and wanted to see under it. I also replaced the stator with one of my used ones. I went to brokeboats.com and found that they had different values for the charge coils and the sensor coils and that mine were within the values that they listed.

I put the fly wheel back on and retorqued it and then tried to start the motor it would not start. I checked for spark and found that I had spark on 1,2,4, and intermittent spark on #3. I recleaned all of my grounds including the ground from the battery cable into the block. The motor wasn't starting so I drained both carbs and switched gas from the main tank to a tank I filled up yesterday. It tried to start and I ended up manually holding the choke shut and got it to crank. (Looks like the spring to the choke lever has stretched) I ran it on the muffs for about 2 minutes and then I switched back to the main tank. I ran it for another 15 minutes or so and it would crank back and run the whole time. I cut it off for about 10 minutes and it again recranked fine. I also had consistent spark on all four cylinders.

I also pulled off the kill switch cord a few times and it cut the motor off like it should. It cranked when I replaced the cord. I also sprayed the key switch and kill switch contacts just for good measure.

I don't have time to take it out today, but hopefully I will be able to tomorrow. The real test will be tomorrow when I get it up to WOT. Hopefully it will keep running after it gets fully warmed up. It seems like it will run forever at 1000 - 1200 rpm on muffs, but dies at WOT. I still don't know that I fixed anything.

 

[iwombat]

Re: Stumped on 1975 115 Johnson

I think it's time to do a real spark-check, as in will it jump a 7/16" gap? Intermittent spark on #3 w/ just the timing light is suspicious enough to think a test might reveal something there.

 

[SparkieBoat]

Re: Stumped on 1975 115 Johnson

again I agree with Wombat...a trip to your local auto parts store for a $5 spark tester is in order..it will become your favorite tool..many times I have identified a weak coil with mine after one of my buddies said " its getting fire I saw a spark in the plug gap while it was laying on the block" . A spark tester tells the real story...I bet you a 3/8" hose clamp that you got a bad coil. That timing light trick aint worth 2 cent for me.
Sparkie

 

[crb478]

Re: Stumped on 1975 115 Johnson

Yes it jumps a 7/16 inch gap nicely. It was also intermitten with two different coils. Once it finally cranked it was no longer a problem and fired as well as the others. Hopefully I can get it out today and see how it runs after getting to wot and warming up completely. That is when it has shut off the last 3 times. Get about 1/2 to 3/4 mile from the dock and it just dies. If you idle around that far it keeps running.

 

[crb478]

Re: Stumped on 1975 115 Johnson

Took the boat out this afternoon and it was the same story, cranked at the dock and then died when it got to wot. I cranked the kicker and went back to the dock and towed it home again. This time it was barely warm, but I at first did not have spark on the #3 cylinder. I switched to another coil and got spark. Did not have time to go back to the ramp so I switched the stator back to the origional one which had the best ohm reading and buttoned it up. I checked spark on all four and opened the gap to 9/16 and it jumped it. Hopefully this is just a case of a faulty coil that fails when it gets hot.

To date the coils are fairly new, and power pack is fairly new. Hopefully I can get it in in the next few days and it will run right again.