HELP!! 1981 70 hp Johnson outboard erratic ignition timing

I have a 1981 johnson 70 hp outboard that hasn't ran exactly right since i got it last summer. So being its cold i decided to do a little tune up. started with a compression test, cyl. 1 is 160psi cyl. 2 is 150psi cyl. 3 is about 160psi as well(being a auto/desiel mechanic I know this is very good). I noticed my carbs weren't exactly opening and shutting all the same so I synced them and got them all opening and closeing in sync. The engine has had the wierdest idle sometimes its high sometimes its low but most the time its high(I found a leaking fuel line since replaced that it hasn't idled low just high all the time) So according to my manual the base idle is adjusted by timing. So I hooked my timing light the the top cyl.(assuming that is #1) and my timing marks are about 90 degrees out and every once and a while it will jump 180 degrees from that spot and then back but primarily stays in the first spot. I can push the lever that adjusts the timing back as far as it goes and it still isn't even close. I think if I can get the timing were it needs to be it will idle right, but im at a loss as to how to get the timing moved back to where it needs to be.

Is there a way to adjust the idle timing back to were it needs to be when it is that far out? It seems that the engine might have been rebuilt before I got it but not to terribly long ago. The previous owner said that they cleaned the carbs and put them back on and that was it but Im not so sure thats all they did.

Another question I have is does this engine have a electronic timing advance for cold start and if it does how do you disable it. My manual doesn't say anything about it but wanted to be sure I don't get kicked in the foot by something simple.

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

Interesting question; deserves a ^BUMP^

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

let me preclude this with, my information is based off of 1983 15hp and 1983 7.5hp jonnys

my 1st check would be to absolutely positively without a doubt make sure that the plugs have the right wires going to them, then i would likely make sure that the timing is properly synced to the carbs...mechanically. my guess is that when they "The previous owner said that they cleaned the carbs and put them back on and that was it but Im not so sure thats all they did" they likely got the carbs both out of adjustment with ea other and out of adjustment with the timing. next thing i would suggest is to make sure when your throttle is all the way down that the carbs close fully, and that the timing is as retarded as it can possibly be mechanically speaking. That may well get you to where you want to be.

other observations, you should likely be able to disconnect the timing from the carbs, then you can manually set the timing where it needs to be and see if you have enough room to adjust to that location. And while it is disconnected you will be able to feel if there is much resistance to moving it, if there is too much resistance to moving it then it may be binding due to dirt or corrosion.

I am not sure if the 70hps were more advanced than the 7.5s and the 15s but neither the 7.5 nor the 15 has any cold start timing change that i am aware of and i have had the 15 apart to the last lil bit.

hopefully someone with much more experience than me will pop in and help you out, i am a newbie to this compared to alot of the others here.

Sean

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

Thanks for the Advice Sean,

I was using a timing light that has a tach built in and something told me to try a different tach so I went to orielly's and but a plain jain timing light and as I was reading the package low and behold the timing light I was using isn't made for marine application. Now the timing is on the money with the timing light but it still bounces around like fifty degrees almost like the coils aren't hooked up right but I checked it and it is correct as far as I know cyl. 1 or/bl cyl. 2 solid or cyl. 3 or/gr as long as the cyl. are top to bottom 1, 2, and 3. So now that the timing is better with my light decided to see why has such a rough idle and what i found was when you close the choke on cyl. 1 (the top one it dies almost imediately) close cyl. 2(middle one and I hardly hear any change in engine sound or rpm) and the same on #3(bottom one) as #2. so i pulled the brand new plugs out and cyl.1 was black like a good burn and 2 and 3 looked brand new but wet. Any ideas would be great.

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

bump! I just bought the same outboard...very interested

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

Interesting problem.
The first suspect is the woodruff key that locks the flywheel to the crankshaft.
If it wasn't properly torqued then it will certainly shear off and throw the timing all over the show.
Use no lube when reinstalling the flywheel on the crankshaft. Clean and dry is the way.

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

Not sure if this may be related to your problem or not, I have a 1980 70hp.

And I had a powerpack go intermittently bad on one cylinder. I kept thinking it was the plug or coil. It just kept getting worse, like running on only 2 cylinders when starting, then kick in when it got warm, to running OK cold & then cutting out when warm. What I finally found was that the previous mechanic had not tightened the coil or powerpack mounting bolts to the block, (which also grounded them). This arcing to ground (which I found after dark quite bay accident) apparently had burned out the windings for one cylinder (#3 in my case).

I fought this for numerous trips over 2 years, trying to cure one & then another small problem that I corrected. When I finally when found the loose parts & the arcing, bit the bullet & bought a new powerpack & runs fine ever since.

Another reason I now do my own repairs.

Re: HELP!! 1981 70 hp Johnson outboard erratic ignition timing

You need a omc manual. That thing will run on 1 cylinder. Make sure your spark plug wires are on right. Also check that the coil wires are right. should be top blue middle orange bottom green. I know because I got a basket case 1981=70hp rude and it took me a bit to get it right.