1979 johnson 35 horse

ok. I got everything back together. Started and ran fine at home. Took it to river and cranked up fine. Eased out to deep water and after a bit increased throttle. She was smooth but not as much power as it should have. So I started tweeking the lean/rich screw, at about half throttle. Then throttle it back up. Did this 3 or 4 times. Once when I did this after getting to full throttle, she all of a sudden went full bore, and was everything I could hope for. I mean she just took off. After a minute or 2 of straight wide open running and grinning like a cat I let off throttle and she died. Tough to start so I went back to 1 1/4 turns from closed and she fired right up, but no real power like before and no amount of adjusting did any better. Filter is super clean, put all new gas lines, new tank, rebuilt carb. She runs smooth so hard to believe one cyl. is not doing it's thing. Lack of spark etc. Compression good in both. Any ideas?? Trying to figure what changed for that brief time where she ran like new. Fuel pump? pressure in fuel bulb stayed consistent. New gas can and air valve open. Haven't had time to pull plugs but I will, and replace them with oem. I checked them both though when I started working on her and they both threw a good spark.

Probably should do a correct spark test and see if you get a good strong 7/16" or so arc.....nice and blue/white color. If that checks out then put some new Champion plugs in. Takes an L77JC4, I do believe. Doesn't that motor have a fixed high speed jet? If that's the case, your adjusting is only effecting low speed running and starting. So maybe you need to look at the carb again and there could be a restriction in the main metering jet area.

Hey Tim
I hear this 7/16 arch test often reading forum. I assume this is measured from wire to top end of plug. Not sure. am I supposed to hold plug 7/16 from ground and arch it? How does this work? Please explain. Tag on plug wire says L78v champion. Has this been replaced with this plug you mention. I will check carb, but just rebuilt it, and cleaned and blew carb cleaner through all ports, and had good flow. I think your right on the high speed jet. only one is accessible while running for lean and rich. It is behind carb cover and hole in cover allows access to screw. I screwed the other one in till it bottomed out then 3 turns out. Does that sound about right, or is that to much. maybe high speed jet is letting in to much fuel and not enough air to let it run at top speed. Thanks for the response, and advise. I will check these when I can and get back to you.

The high speed jet ( orifice plug ) is in the bottom of the float bowl.------It is screwed in tight and is NOT adjustable.----Sparkplugs are not used to test maximum ignition voltage output.

O.K. Racerone
If it isn't to much trouble, and time please share the correct way to check my ignition voltage. You seem knowledgeable on outboards from what I see you sharing on forum. I am not familiar with outboard motors, but am wanting to learn. I've already learn a lot from what I have done so far. I could just take it to a shop, but I am one of those who enjoys the doing it myself, and learning something new. Also the challenge of finding and fixing older things. Just because it's broke doesn't make it worthless is a common saying of mine. I appreciate your input.

Racer is highly experienced, probably one of the top guys on ANY outboard forum. He wants you to check the spark directly to a ground and not to the top of a spark plug. This will insure no outside influences to let spark be disturbed.

Get an adjustable spark tester that can be set to different gaps NOT one of the inline lights. Local auto parts stores sell them for around $10. Set the gap to 7/16" and plug it into the plug wire and attach it to a good ground on the motor. The spark should be able to jump that gap easily. The high speed does not work the way people think it works as a fuel restrictor. Have you tried pumping the primer ball while running to see if it makes a difference.

The high speed orifice or jet in this motor is engineered to supply the correct amount of fuel without any adjustments, as Racer spoke. Mr. Scott has explained the spark test very well too. When cleaning the high-speed orifice or jet it is important to make sure there are no deposits on the walls of the opening. In some cases the cleaning procedure is incorrect and does not get the deposits which can restrict flow causing a lean operating condition.

O.K. Guys
Thanks for the info. I will get a tester on way home, and check that. Then I guess I'm going to have to pull carb and check that jet. Thanks a lot for your input. I figured it was fuel or spark, wondered if had restriction in intake or exhaust manifolds so she couldn't breath. All these things can cause same effects on engines power, and running smooth, as they should. I found engine on craigs list. Laying in a sand pile. It didn't look to good, but had good compression, so I decided to risk it, after he came down on price. I ask for no discount but when he saw I was checking things out he came down 150 bucks. I think I have a good strong motor. Once i get her running right I will pull lower end off again and rebuild water pump, and paint her up, and get some new decals. The cover needs new seal and has a few spider web cracks. Thanks again for your help. I will keep you posted on progress.

I got a tester, and set at 7/16 grounded to head and had brother pull her 3 times on each cyl. Nice blue arch on both. Plugs seem to have real good arch as well. previous owner put NGK in there. Good plugs but ordered some champion L78V, which is what is oem. So Coils seem to be doing their job. Tomorrow I will try and pull carb and see what's up in there. I will keep you posted. Thanks again for your help. I did check bulb several times while running and pressure seemed good. Should I go ahead and rebuild the fuel pump and get that out of the equation. Now that I know the engine is solid I will be ordering the water pump anyway, just so I know that is in top shape. No idea how old it is. Seems to work well but don't want to risk that issue.

Don't put too much faith in "OEM" plugs. There is a reason evrybody abandoned them and put in QL77JC4, including OMC in later years.

You don't actually have to pull the carb if your only goal is to check the high speed jet. But it does take a special screwdriver to get it out without damage, either way.

Thanks for that info. Wasn't aware of the champion issue. I'll bet that special screw driver is special. Things are a little offset and tight, down there. one of those things you do by feel more than sight. I am going to go ahead and pull it and get it on a bench with a lot of light and some magnification to inspect all the ports again. Especially that high speed jet. I am pretty sure that this is the issue. I didn't understand how it worked, and thought it was a plug sealing that part of carb off, but kind of like a clean out access when carb needed cleaning. Or a port not used on this model that didn't need as much gas. I didn't realize it was the high speed jet. So I sprayed it down but didn't remove inspect and clean. So now I have learned something, which is why I enjoy the forums. There are those in the know, sharing with those who are not. The amount of time and frustration this eliminates is huge. Thanks for responding. Keep you all posted.

We all all here to help, keep up the good work.