1969 Johnson 115 HP misses

Jeff Yoscovits · Aug 16, 2001

This motor is missing and has no power. To date I have rebuilt the carbs, replaced distributor cap and rotor and replaced the wiring to the CD sensor in the dist due to the wire insulation rotting and the two blk/wt wires shorting together. Problem seems to be an ignition miss but I'm not sure. #4 cylinder does not seem to be working. Can it be possible that the sensor wiring problem caused a problem with #4 cyl only. I would have thought that the motor would not even run w/ these wires shorted together. I've heard a pinhole in the fuel pump diaphragm could also cause this. I disassembled the pump and don't see any holes in the diaphragm. Am I missing something? Are there any quick tests for the power pack to isolate this problem? The tests in the manual I have are somewhat vague.Any help would be appreciated. Thanks, Jeff.

JB · Aug 16, 2001

Re: 1969 Johnson 115 HP misses

Howdy, Jeff. You've made a good try to explain your problem in detail, but it still seems a little vague. Lets clarify a few things. Does "missing" mean that one cylinder does not fire at all, or does it mean the engine intermittently skips a cylinder? Does this happen at any particular speed range? Does "no power" mean reduced power? Reduced how much? Does this happen at idle, under no load or only under load? What did you see or do to make you believe that #4 is not working? Does it happen when the engine is cold or only after it is warmed up? Standing by. JB

Jeff Yoscovits · Aug 16, 2001

Re: 1969 Johnson 115 HP misses

The engine seems to run rough at idle and off idle. On the water I could only get approx 10 mph in my 17 ft Performer. I pulled the wires one at a time to isolate the miss. This appears to happen hot or cold. One thing I left out was that I also replaced the L77JC4 plugs w/ QL77JC4's. I don't know if that makes any difference or not. I just installed this motor on this boat. The previous owner states it ran fine for him last in JUly 2000. Thanks, Jeff.

Rex · Aug 16, 2001

Re: 1969 Johnson 115 HP misses

CHECK THE BOTTOM CARB. AND THE WIRE FOR SPARK. NEED MORE INFORMATION.

Jeff Yoscovits · Aug 16, 2001

Re: 1969 Johnson 115 HP misses

Rex, the motor has 135 compression in all cyls. I pulled the wires one at a time to locate miss. I hear spark from all wires, but I haven't checked strength of spark. As I stated in first post, the carbs have been rebuilt. I didn't see anything unusual when they were apart, actually they were exceptionally clean inside.The wiring to the CD sensor was deteriorated and shorted together. I would have thought that the motor wouldn't even start. Could this affect the power pack? The tests in my manual say to use a neon test light and an ammeter connected in series w/ the power pack wiring, but the diagram is vague. Do I have to disconnect the pur/blk wire from the panel to connect the ammeter? I am an auto tech and I have never used a neon test light. Can anything else be used? The manual is also vague about the synchronisation adjustment. Can you shed any light on that,and if so, what is the easiest way to do it? Can a power pack problem affect just one cylinder? Is there any easy way to check for a hole in the fuel pump diaphragm? I took it apart and didn't see anything. also, there was no fuel in the vacuum hose. Any help is greatly appreciated. Thanks, Jeff.

JB · Aug 17, 2001

Re: 1969 Johnson 115 HP misses

Top o' the morning, Jeff. I now have a much clearer picture of your problem. Unfortunately, you have the one year for which I don't have diagrams between 1922 and 1989, so I am working with the diagram for the '68 115 and know there may be differences. Just to summarize: I believe you have a CD ignition system with a single powerpack, a pulse transformer (coil) and a distributor which provides spark to all 4 cylinders. As I understand it, if you pull the plug wire for #4 there is no change, but you think there is spark there. You need to verify that. Can you get a 1/2" arc from that wire to the block? I don't see anything in the ignition system that would take out only one cylinder before you get to the plug wire and the plug. Assuming, for the moment, that you have spark to #4 but it still doesn't make power, you have confirmed good compression, and cylinder #2 is making power (you overhauled that carb). . . you might have a bad reed, a leaky bypass cover plate or a blown bottom crank seal. Let me know if my above assumptions are correct. If they are, inspect the reed plate and bypass cover plate for the bad cylinder. If I have assumed wrong, straighten me out and we'll start over. Good luck. Red sky at night. . . JB

Rex · Aug 17, 2001

Re: 1969 Johnson 115 HP misses

I AGREE WITH "RED SKY IN THE NIGHT" CHECK THE PLUG WIRES WITH A OHM METER TO SEE IF #4 IS BAD. IF NOT I WELL GO WITH CHECKING THE SPARK ON IT. IF YOU HAVE SPARK PULL THE PLUG AND CHECK FOR GAS ON IT. IF NOT YOU KNOW WHERE TO START. THE PUMP AND THE CARB.

Jeff Yoscovits · Aug 17, 2001

Re: 1969 Johnson 115 HP misses

I tested the spark. Got about a 3/8 in arc. comparable w/ other cyls. replaced the # 4 wire anyway. No change. Plug was fuel soaked. I'm leaning toward a hole in the fuel pump diaphragm. Was told repair kits are available, but my manual says the pump must be replaced. Any info on that? Thanks again, Jeff.

JB · Aug 17, 2001

Re: 1969 Johnson 115 HP misses

Hi, Jeff. Whatever is causing only one cylinder to fail to fire almost has to be unique to that cylinder. When OMC fuel pumps give trouble it is almost always going to affect all cylinders, unless it is the cylinder that drives the pump. I don't remember which cylinder drives the fuel pump on your engine and none of my books mention it, but if it is mounted on the crankcase for #4 it could be the culprit. There should be overhaul kits available, though my manual agrees with yours. . . "serviced as an assembly". Cursed nonsense, as though the castings are going to fail! Y'know, #4 could be failing because of flooding. . . not loss of spark or fuel or compression. If the fuel pump were leaking into the crankcase that runs it, and that crankcase is for #4, that would explain it. That would also explain why you got the "hole in the diaphram" advice. BTW, I don't like your spark strength. You should be able to get 1/2" from that CD unit, but I don't think that is your current problem. While you are overhauling the fuel pump and have it off the block, cycle the crank a few times and see if you are getting good pressure/vacuum cycles at the hole that runs the fuel pump. This would verify that the reeds are seating well. I think you are on the right track, Jeff. Go for it! Red sky at night. . . JB

Jeff Yoscovits · Aug 18, 2001

Re: 1969 Johnson 115 HP misses

I replaced the fuel pump this morning and also disconnected and cleaned every wire on the engine per the Johnson dealers advice that these motors were very sensitive to any poor connections. After doing all this I fired up the motor and it ran worse than ever. Quits for no apparent reason. restarts ok and then will just die. Fuel pump seems to have had no impact at all. I have inspected nearly every wire on this thing. Everything looks ok. Any other suggestions? Thanks, Jeff. P.S. The part # for the fuel pump that I was given is 348559. The dealer only had a #348557. Looks identical. Swapped back old pump. No change. Still quits and runs terrible. I'm thinking wiring.

Rex · Aug 18, 2001

Re: 1969 Johnson 115 HP misses

IS #4 THE ONLY PLUG THAT IS FOULED? THE MORE INFO THE BETTER.

JB · Aug 23, 2001

Re: 1969 Johnson 115 HP misses

Hi, Jeff. Saw your other post. Did you check out the pressure/vacuum in the crankcase for #4? The bypass cover is the trapezoidal plate bolted to the side of the cylinder. I can't do anything with "runs worse" and "runs lousy", true as they may be. Could it be that more than one cylinder is not making power?? Usually those V4s seem okay running on three with no load. Do the, "Pull each plug wire and does the engine slow or not?" test again. Also do the "spray WD-40 into the bottom carb while it's running, what happens?" test again. Though you and I may reach the same conclusions from what you see, don't tell me your conclusions, tell me what you did and what you saw. Standing by... JB

Jeff Yoscovits · Aug 25, 2001

Re: 1969 Johnson 115 HP misses

Hi J.B., I had pulled the reed block out to inspect and the reeds look like new. I also pulled off the bypass cover. The gasket was in excellent condition.Johnson dealer suggested to inspect the piston for galling through the bypass openning. The piston skirt looks like new. From what I could see, therewas very little carbon on the piston top.After reassembly, I fired it up. The motor was still missing immediately. Sprayed WD-40 in carb. Nothing happened in #4 cyl. Sprayed each carb bore, idle rose when #1 and #2 sprayed. Nothing in #3 and #4. I pulled the wires one at a time and each cylinder had an even drop except #4 which was dead. I had a good near 1/2 in spark. I may be wrong on this, but it seemed like when I went to reconnect #4 the motor popped then died. Again, it always fires right back up. Where can I get a diagram of the dist firing order. I know it may sound stupid but when I was in auto shop 25 yrs ago, the instructor always reminded us to "Keep It Simple Stupid".I would just like to reverify that I didn't do something stupid like misrouting my plug wires. Thanks again, Jeff.

JB · Aug 25, 2001

Re: 1969 Johnson 115 HP misses

I sympathize with your frustration, Jeff. I think a plug wire switch would have dropped two cyliners, rather than one. From what you have done and seen so far, I have few ideas. One possibility is still a blown seal at the bottom of the crankcase, preventing adequate scavenging. I would have thought that the WD-40 treatment would have gotten it to at least pull its own weight. Because you got good, and even, compression I don't think the problem is in the cylinder. It seems to have to be in the crankcase or carb throat for #4. AHA!! OKAY!! I just got a surprise. I was thinking that your engine had two, 2 barrel carbs and that #2 and #4 shared carb circuits. They don't. You have the four barrel carb that is really four carbs in one casting and #4 has its own circuits . . .right down to the float. Problem. This is a very complicated carb (even though it is just four simple carbs in one unit). If you dismantle it, be sure to keep all of the parts for each barrel seperate, don't let them get mixed. You mainly want to examine and clean the parts for barrel #4, but if in doubt do 'em all. If you decide to switch parts from some other barrel into #4 for troubleshooting purposes, swap the parts as a set, not piecemeal. I sure hope this fixes it, Jeff. You've earned it. Red sky at night. . . JB

Jeff Yoscovits · Aug 25, 2001

Re: 1969 Johnson 115 HP misses

Hi J.B., you were right with your first thoughts about the carbs. I do have two 2 BBL carbs. In your earlier post you mentioned checking the crankcase vacuum and pressure. How would I go about doing this? I feel that I'm going to kick myself when I do eventually find the problem. For some reason I just know it's going to be something basic that I'm overlooking. Thanks again, Jeff.

JB · Aug 25, 2001

Re: 1969 Johnson 115 HP misses

Oh, rats! I forgot I was looking at the '68 115. Sorry 'bout that. Well, let's see if we can figure a way to assess the pressure/vacuum in the #4 crankcase. But first, examine the bottom carb to see if you can see a way that it could be flooding #4 without flooding #2. Do the 2 barrels feed #2 and #4 seperately? Could a circuit for #4 have a loose part, permitting too much fuel flow? Does the fuel pump run off #4, or one of the other cylinders? Is there any fitting, hose or other access to the inside of #4 crankcase where you could at least stick your finger over it and feel the pressure and vacuum when the engine turns over? I am getting groggy with this thing. Try those ideas out and I will sleep with my crystal ball. If I have any new ones I will post in the A.M. Red eyes tonight. . . JB

Walter · Aug 26, 2001

Re: 1969 Johnson 115 HP misses

I like your shop class instructor's advice! Keep it simple. Jeff, I've yet to understand why a plug that's been fuel fouled can fail to spark afterward...but try this. Swap your #4 spark plug with one from a cylinder you know is firing. See what happens. Walt PS I can certainly appreciate your frustration here. Just remember...it's only a machine and ANYTHING can be fixed. BTW. You say the carbs have been rebuilt. You also say the engine ran fine last year. Exactly when did it start to run poorly? Was it prior to any of the repairs you described in your above posts? And these repairs were in response to it's running poorly? OR, did the poor running issue surface AFTER the above mentioned repairs began? Just trying to get a perspective here... Good luck...hang in there. Walt

Jeff Yoscovits · Aug 26, 2001

Re: 1969 Johnson 115 HP misses

Hi Walt, I just purchased this motor on another boat. It ran ok when I looked at it before buying it. I swapped it onto my boat and that's when the trouble seemed to start. It is possible, of course that I may have missed the problem when inspecting because the lower end was in a barrel of water and w/ just a pair of rabbit ears on it the exhaust isn't muffled like it is in the water. The carbs were rebuilt by me after the dealer suggested it was necessary. All other repairs were performed by me trying to solve this concern. Hope this gives you a little more insight. Thanks, Jeff.

Jeff Yoscovits · Aug 26, 2001

Re: 1969 Johnson 115 HP misses

J.B., the fuel pump does run off of the #4 cylinder. I haven't had a chance to check the vacuum/pressure there yet. As for the barrel for #4 it does appear to supply only that cylinder. It would seem though that turning the mixture screw in all the way would have at least some effect on it. I will try to check that vac/pres this pm and let you know how I make out.Thanks, Jeff.

Walter · Aug 26, 2001

Re: 1969 Johnson 115 HP misses

I should probably just stay out of this 'cause it sound like Jeff and JB are slowly going through the process of elimination...and that's what it's gonna take to resolve this. However, I'm still puzzled by a comment Jeff said in his fourth post...cylinder #4 plug was fuel soaked. Later he said spraying WD into #4 carb didn't raise the RPM...and finally he said pulling #4 plug wire didn't lower the rpm. That's telling me that #4 plug is not making a spark...for whatever the reason. I'll shut up now...and wait to see what you guys figure out! Definitely keep us posted...this is an interesting one. Walt

1969 Johnson 115 HP misses

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