1975 Johnson 9.9 has no power

[ss_rider]

I picked up a 1975 Johnson 9.9 a few weeks ago. Owner said it was runing good last year when he put it away. When I got it home I took the carb off and gave it a good cleaning and it all looked good. It started good after that but when I took it out on the water it had no power and was "surging." I pulled the plugs and the lower cylinder looked as though it wasn't firing and was fouled. It has good compression and both plugs are sparking. So I picked up some new NGK B7HS plugs and installed them today and took it out on the water again. It seemed to run a bit better with less "surging" but it still had no power. I'm stumped on this problem, the motor is getting fuel, spark, and has good compression. I should also note i have to have the idle set rather high to keep it from stalling. Any ideas?

 

[OptsyEagle]

Re: 1975 Johnson 9.9 has no power

When you say it has spark, how did you determine this. I would do a proper spark test with an external spark tester to ensure both cylinders can jump a 3/8" gap. Second, I would start it up and with insulated plyers I would remove one spark plug boot at a time. That motor should run fairly well on one cylinder. If the motor dies when one boot is removed it will confirm my suspicion that you are running on only one cylinder and also confirm that the other cylinder is the one that is dead. If a cylinder does die when a boot is removed, I would hook up the spark plug boots to the opposite cylinders. Althernate the coil clips as well and start it up and do the boot removal test again and see if it moves to the other cylinder. If it does, the problem was most likely electrical (a coil or point) and if the problem stays at the same cylinder it is something else (blown gasket, crankcase seal, water in cylinder, etc.).

A compression test could be useful as well.

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

When you say it has spark, how did you determine this. I would do a proper spark test with an external spark tester to ensure both cylinders can jump a 3/8" gap. Second, I would start it up and with insulated plyers I would remove one spark plug boot at a time. That motor should run fairly well on one cylinder. If the motor dies when one boot is removed it will confirm my suspicion that you are running on only one cylinder and also confirm that the other cylinder is the one that is dead. If a cylinder does die when a boot is removed, I would hook up the spark plug boots to the opposite cylinders. Althernate the coil clips as well and start it up and do the boot removal test again and see if it moves to the other cylinder. If it does, the problem was most likely electrical (a coil or point) and if the problem stays at the same cylinder it is something else (blown gasket, crankcase seal, water in cylinder, etc.).

A compression test could be useful as well.

Thank you for your reply. I determined it has spark by pulling out the plug and holding it against bare steel on the motor for a ground, then having somebody pull the motor over. It looks to have a strong spark. I will try pulling off one plug at a time and see if it dies, which i suspect it will when I pull the top plug. Also I have checked the compression and I can't remember the exact numbers but both cylinders were around 100 pounds.

 

[Rick.]

Re: 1975 Johnson 9.9 has no power

There is a difference between spark and good spark. If she stalls when pulling the plug wires you will need to pull the flywheel and check your points. They need to be in good condition, gapped to .020 and very clean. Best of luck. Rick.

 

[ultra353]

Re: 1975 Johnson 9.9 has no power

Surging sometimes indicates an vaccuum leak, start motor and spray wd-40 around all the gaskets and crankcase half`s of motor. If rpms pick up you`ve found a leak. Also check your fuel pump for a leaky diaphram, if its getting its pulse off the bottom cyl it might be flooding out the bottom cyl.

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

Okay so I tried pulling the plug wires while running and the motor stayed running for each plug. It seemed to run the same on each cylinder so I'm guessing spark is not my problem. I also sprayed carb cleaner around the motor while running and my idle did not speed up so there doesn't appear to be air leaks. The motor seems to run a bit better if I lean out the fuel screw almost 3/4 turns (I previously had it backed out 1.5 turns from all the way in) but it still is not running right. The plugs were pretty wet when I pulled them out after running it again. When I cleaned the carb the needle and seat seemed to be in great shape but maybe it is leaking and flooding the motor? I pulled the fuel pump apart and the diaphrams didn't have any tears in them. I'm wondering if I should buy a proper spark plug tester or maybe a complete carb rebuild kit

 

[OptsyEagle]

Re: 1975 Johnson 9.9 has no power

OK, so it is still not running right. What exactly do you mean by that? Difficult to keep going at idle, or surging, or mis-firing? Originally you indicated that the motor had little power and was surging. If this condition was spark related, surging would be the symptom of spark intermittently failing and killing a cylinder (that's the low power) and then it coming back (that's the surge). So the fact that both are firing right now is not necessarily an indication of dependable spark or the elimination of spark as an issue.

I am also not sure what you mean by leaning out the carb adjust 3/4 turns. You had it out 1.5 turns and then turn it clockwise 3/4 so that it is now only 3/4 out or turned it counter-clockwise and now it is 2.25 turns out? You probably should ensure that it set properly if you can. The procedure would be to turn it out 1.5 turns (from seated), warm it up, reduce the idle to just keep it going and then turn it in (clockwise) about 1/8 of a turn at a time. Leave it for 5 seconds, reduce the idle to just keep it going, etc. When it start to cough and sputter, turn it back out (counter-clockwise) about a 1/3 of a turn and that's where you want it. Mine is usually only out from seated about 1/2 to 3/4 of a turn. Yours maybe different.

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

OK, so it is still not running right. What exactly do you mean by that? Difficult to keep going at idle, or surging, or mis-firing? Originally you indicated that the motor had little power and was surging. If this condition was spark related, surging would be the symptom of spark intermittently failing and killing a cylinder (that's the low power) and then it coming back (that's the surge). So the fact that both are firing right now is not necessarily an indication of dependable spark or the elimination of spark as an issue.

I am also not sure what you mean by leaning out the carb adjust 3/4 turns. You had it out 1.5 turns and then turn it clockwise 3/4 so that it is now only 3/4 out or turned it counter-clockwise and now it is 2.25 turns out? You probably should ensure that it set properly if you can. The procedure would be to turn it out 1.5 turns (from seated), warm it up, reduce the idle to just keep it going and then turn it in (clockwise) about 1/8 of a turn at a time. Leave it for 5 seconds, reduce the idle to just keep it going, etc. When it start to cough and sputter, turn it back out (counter-clockwise) about a 1/3 of a turn and that's where you want it. Mine is usually only out from seated about 1/2 to 3/4 of a turn. Yours maybe different.

It was having difficulty idling and also missing. I decided to check the points and they were a bit dirty and way out of spec. They were set at like .012 but should be .020. So I cleaned them and set them at .020 and it seems to idle much better now. I haven't had a chance to try it on the boat yet but running it in a barrel it seemed to still have a slight miss when reving higher, but its hard to tell without trying it on the boat.

I also bought a spark tester and both plugs have no problem jumping a 3/8 gap. I did notice the bottom coil has a hairline crack in the rubber coating. Coiuld this pose a problem?

Sorry for the confusion, my fuel screw was initially turned out 1.5 turns from seated. I turned it clockwise and it is now 3/4 turns out from seated.

 

[nphilbro]

Re: 1975 Johnson 9.9 has no power

The gap should make a big difference. I run mine between .30 and .35 usually (but it's just a trolling kicker).

If you still don't like how it runs check the carb jet from the float bowl. If it's partially clogged it will severely starve your motor. As others have said before use the bare wire from a twistie to unplug it.

This motor also has a metal float bowl and ethanol can really mess it up. I picked one up ('77-9.9) a couple days ago that hadn't been run in 5 years and took the carb apart before even trying to start it. There were pieces of rust and "resin" on the bottom of the bowl that probably clogged the jets - giving me a cheap motor. This resin is residue from old lines.

I added a new gasket where it mates to the block too since the original was pretty worn - air leaks will also cause heck with it if there's even a tiny leak in the gasket. I didn't add any other new parts and it started right up and ran well. I cut my own gasket (be sure to get fuel rated) for this since it's pretty simple. I'm a big proponent of doing the cheap and simple to start. It's also a very common problem since many haven't been converted for ethanol.

While you're at it. Replace the 2 fuel lines (if they're old) to make sure they are ethanol safe too or you'll be cleaning the carb out every time you turn around.

A clogged jet could possibly explain why it runs better tuned so lean - more steady fuel, albeit, a small amount.

Good luck. Let us know what works.

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

I finally got it out on the water last night. Runs WAY better now with the points adjusted. Does 25km/h (16mph) on my 12' v-bottom aluminum with me (185lbs), a full tank, and about 20lbs of gear. The miss appeared to be completely gone when I first started cruizing, however after cruizing wot for about 10 min it missed intermittently for a period of about 5 min, then seemed to go away again. It was still maintaining speed but you could definatley feel it was missing. It did this a couple times in the hour long ride. I'm not sure what could be causing this. Plugs also look good, jetting is right. Any ideas?

 

[Daviet]

Re: 1975 Johnson 9.9 has no power

Could you use a timing light to check the spark on each cylinder when it misses, maybe you have a coil or a set of points acting up when hot. At least you will confirm or deny if it is an ignition problem.

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

Could you use a timing light to check the spark on each cylinder when it misses, maybe you have a coil or a set of points acting up when hot. At least you will confirm or deny if it is an ignition problem.

I'm not too familiar with using a timing light, how would I do that? Could I use it while I was driving the boat. There is a hairline crack in the rubber coating of my bottom coil. I sealed it with RTV but I suppose that coil could be my problem

 

[Daviet]

Re: 1975 Johnson 9.9 has no power

Question, what plugs are you running?

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

Running a NGK B7HS

 

[Daviet]

Re: 1975 Johnson 9.9 has no power

You might want to try running the champion plugs that are suggested for your engine. I don't think there is a direct conversion for the champion plugs and the heat range might be a little different and causing your problem.

 

[ss_rider]

Re: 1975 Johnson 9.9 has no power

You might want to try running the champion plugs that are suggested for your engine. I don't think there is a direct conversion for the champion plugs and the heat range might be a little different and causing your problem.

I tried getting them but nobody carries them and they are special order apparently (for a ridiculous price). I had read on Leeroy's Ramblings that this NGK actually performed better with this engine.

I just had the boat out on the water but with two people in it this time. It was missing really bad when trying to accelerate again. If I held it wide open for 5 to 15 seconds it would eventually stop missing and run smoothly, although I feel it was lacking top end power. I'm wondering why it would miss much worse with 2 people vs just myself. Must have something to do with the load on the motor. Would a bad coil cause a problem like this?

 

[AlTn]

Re: 1975 Johnson 9.9 has no power

yes