1969 Johnson 115 HP misses

[kb]

Re: 1969 Johnson 115 HP misses

hey ya'll, i'm brand new to this board and decided to register after seeing this topic.<br /><br />I AM HAVING THE SAME PROBLEM!<br /><br />i have a 73 johnson 115 ob. i have replaced all four coils, stator, cd, all plugs and wires, so i think i have exhausted those possibilities. <br /><br />i was about to start in with a carb overhaul, but after seeing this thread, i will hold off until ya'll come to a solution.<br /><br />if there is anything i can contribute let me know as i'll be checking this board regularly this week.<br /><br />great board, thanks guys.

 

[kb]

Re: 1969 Johnson 115 HP misses

upon rereading one of the original posts, i found a couple of differences in our performance, jeff. that is, my engine runs rough at idle and off idle only after it runs for a bit( 10 min or so) and once i hit cruising speed my engine runs fine( or seemingly so).

 

[JB]

Re: 1969 Johnson 115 HP misses

Hey, Walt! Please jump in if you have an idea. My current suspect is #4 flooding, but I can't remember if we have confirmed that the #4 plug is actually firing. We do know that spark is getting to the plug, but I don't remember if we have tried swapping it out. The plugs are new, and we old timers know that new stuff fails more often than old stuff.<br /><br />Hey Jeff. If you haven't tried it, swap the #4 plug with another cyl. and see what happens.<br /><br />Red sky at night. . . <br />JB

 

[JB]

Re: 1969 Johnson 115 HP misses

Hey, Jeff. Here's a long shot, but it will cost nothing to check it out.<br /><br />In my manual on old Johnnys, up to '68, there are several places where the instructions mention a vacuum switch. It doesn't show in any of the wiring diagrams but does show up in some pictures of 2, 3 and 4 cylinder engines. I finally ran on to an explanation of what it does (on the 3 cylinders, at least). If open throttles are suddenly closed, the resulting vacuum in the intakes can create a "false open throttle" and cause engine runaway. The vacuum switch disables the ignition for the BOTTOM (!!) cylinder to prevent the runaway. <br /><br />There is no vacuum switch shown in the wiring diagram for the '68 115hp, but there is one in the picture of it, and a procedure for checking it! I wonder if there is one on your '69.<br /><br />Look for a round, black, (about 1 to 1.5") flat device with 2 wires located on the side of the engine near the starter motor. If there is one, and if it has the same function as the one on the older 3 cyl engines, it just may be your culprit. I have no idea why it is pictured, even has an adjustment procedure, and doesn't show in the wiring diagrams. It might also be used to prevent starting with open throttles. A "safety" switch does show in the diagrams, that can open the circuit to the solenoid primary.<br /><br />If you have one, where does it get the vacuum?<br /><br />Red sky at night. . .<br />JB

 

[Walter]

Re: 1969 Johnson 115 HP misses

Geez...Poor Jeff has been blasted with so much info I think he needs a few moments to catch his breath. I'm waiting on the side to see what transpires. Interesting what JB posted regarding the anti-runaway vacuum switch. While we're waiting to hear back from Jeff...I'll ask a buddy of mine who once owned a '69 Johnson 115 if he recalls there being one on his engine.<br /><br />Walt

 

[SCO]

Re: 1969 Johnson 115 HP misses

This is an interesting thread. At some point,when all ideas are exhausted, if your carbs are identical, you can switch them to see if the miss goes to another cylinder. The throttle linkages and choke baffle linkages were different on the twin carbs of my engine, but could be switched from one carb to the other or manually operated for the test. Also, an untested idea, put one of these small rotary windspeed indicators in front of each barrel with the engine at some midrange speed to see if they are all drawing equivalent amounts of air. That probably wouldn't work at idle. Be careful with the rotating parts( no tie) and suction at the barrels.

 

[rwise]

Re: 1969 Johnson 115 HP misses

Hey Jeff<br /><br />You said it "poped" then died when reconecting the number 4 wire back to the plug. You might try holding the wire about 1/4" away from the plug electrode and see if it trys to hit. This worked on fouled plugs in my dirt bikes, would then replace the plug if it hit! You will find the problem, sometimes it helps to take a break though!<br /><br />Richard

 

[Jeff Yoscovits]

Re: 1969 Johnson 115 HP misses

Hi guys, I just picked up a new plug on my way home. I'm going to screw it in and see what happens. J.B., I'll take a pee k and see if there is a switch like you described. Thanks for all the help. sooner or later we'll get this thing right. Jeff.

 

[Jeff Yoscovits]

Re: 1969 Johnson 115 HP misses

Hi all, well, I picked up a new plug and screwed it in, fired up the motor and noticed no immediate improvement. Then Mr Murphy of Murphy's Law fame stopped in. The motor stalled and while cranking to restart it kicked back and sheared the flywheel key. No other damage observed. I replaced the key today, fired it up and the motor appeared to be loaded up. I ran it just off idle for a minute or so. It now seems that #4 is working. This motor still doesn't seem 100% though. The #3and #4 cylinders don't drop as many rpm's as #1 and #2. I adjusted the carb mixture screws, and all 4 are at approx 1 1/2 turns out. Could it be that the motor is just loaded up from idling in my driveway and it needs to be blown out a little? The engine also seems to idle faster than I think it should. I don't have a tach hooked up, this is just by ear. An aquaintance suggested spraying starting fluid around the bottom of the powerhead to see if the bottom seal was leaking. I know that starting fluid isn't a good idea, but what about WD-40? By the way, is there a certain type of tach that must be used? The wiring is there to the dash. Thanks for all your help. I think we may be getting close to success. Jeff.

 

[Liam]

Re: 1969 Johnson 115 HP misses

have you performed a compression test on all four cylinders? It sounds like 3 & 4 aren't contributing as much power as 1 & 2. Glad to hear that 4 is firing again but remember things that go away by themselves can always come back by themselves.<br /><br />keep smiling,<br /><br />Liam

 

[Jeff Yoscovits]

Re: 1969 Johnson 115 HP misses

Hi again everyone. Well, I finally had time to fire this motor up today. It's still running rough. I adjusted and then readjusted the mixture screws. Then, I sprayed a fuel mixture into each throttle bore. Enrichening the cylinders had the same effect on all cyls. Then I pulled the spark plug wires. Each cylinder now drops about the same. This tells me i don't have a fuel or spark problem anymore. Could I have a timing problem. My manual says the timing is adjusted at 4500 rpm. The motor does stall at times and it just seems that it's not firing at the right time. I think we've almost got it solved. Thanks, Jeff.

 

[Walter]

Re: 1969 Johnson 115 HP misses

Jeff...<br /><br />Well, I finally spoke to my buddy who once owned the same year/hp etc. engine as yours. He doesn't recall a vacuum switch to prevent runaway...but he sure recalls the numerous power packs he had to replace during the years he owned it. He said the power pack never failed in the same manner. One time it wouldn't allow any spark whatsoever...the next time it failed, it ran rough as though it were a fuel problem. Sound familiar? <br /><br />Anyway, if you haven't resolved the problem yet...and have access to a known good power pack that you could bolt on and try...I'd suggest you consider the possibility.<br /><br />FYI...<br /><br />Walt

 

[Jeff Yoscovits]

Re: 1969 Johnson 115 HP misses

Hi all, today I'm posting as a very happy boater.After replacing the flywheel key with the proper size key the engine is now running fine. It turns out that the key that sheared was thinner than what should have been there. This, I believe caused slop between the flywheel and crank and threw off the timing.I fired the motor up in my driveway and it appeared to be running ok, so I decided to drop it in the Detroit River this PM. The motor just purred. Accelleration was excellent. One problem I noticed was a hard pull to the right and the left side seemed to dip down at higher throttle. Any suggestions on that concern? Other than that, I would like to thank everyone for their help. Perhaps someday I can return the favor. Thanks again, Jeff.

 

[Walter]

Re: 1969 Johnson 115 HP misses

Hey...that's great she's running well for you! I guess your shop teacher was right!<br /><br />Keep it simple!!!<br /><br />Congrats...Good job!<br /><br />Walt<br /><br />PS I'll bet that flywheel key was a bit cheaper than a new power pack too!!

 

[Jeff Yoscovits]

Re: 1969 Johnson 115 HP misses

Does anyone have any ideas about the pulling problem? The tab on the lower unit above the prop was turned approx 10 degrees toward the port side at the rear of the tab. Could this need adjusting? Thanks again to everyone, Jeff Yoscovits.