1970 Johnson 9.5hp list of problems

[Mr_Toogie]

Hi,
I'm new to the forum but I've gotten a lot of useful information form other threads I figured I'd start one for myself with my list of minor problems. I have an old 1970's Johnson 9.5 hp outboard that I've been using for years. It's been a great work horse for getting me around the lakes I fish. This year I had to do some carburetor cleaning and replace my gas line, but after reading up on the motor I've learned that it has never really running at it's full potential and still isn't. I'd like some suggestion on what i can do to get it there. So here's the list of minor problems I've been having and if anyone have some answers i'd like to hear them.

The first issue is, I have problems with it idling, or slow speed operation. It'll start and run good as long as i don't bring the throttle all the way down. When i make the idle speed and mix adjustments i can get it to idle great but after i get going and get to my fishing spot and bring my throttle down it sounds like it's running out of gas and dies. when i try to get it started up again it take a little bit of effort but once it's running again it run good. Any thought's

The second issue is, I could use a new propeller for my motor, I know it's an 8 1/8 X 8. What i would like to know is what replacement propeller i should look into to get the most out of my little motor. The propeller I have on it now has seen better days but it still works... for now.

The third issue I've been having is Top speed, Although my little motor runs like a champ it never seems to sound like it's hitting it's max RPM at WOT. from the first day I've used it, it's always seemed to me that it just wasn't giving me all it had. I have a 12' alumcraft and according to my GPS i never get the boat over 7 MPH. Now before I did my researching i just assumed that was the best i was going to get out of it and on the lakes i fish i really didn't need much more... but If i could get a little more out of it would be fun.

The fourth and last issue i have The lever and pin on the end of the throttle shaft had come lose recently and I tighten it back down but i know the placement has moved so I've been trying to figure out exactly what position it should be in. I'm guessing the throttle valve should be closed all the way with the pin just touching the cam follower. Is that right? Also, I'm pretty sure this isn't what's been causing all my problems... It's still running exactly the same as it did before i tighten the lever and pin.

Well, these are the issues I've been having, If anyone have any idea's let me know. The issues I'm having, I've been having for years but didn't really think much of them. The little motor has always done it's job for me. I can always get it started, It has always gotten me to where i wanted to go and it's always gotten me back to the dock again. I'd just like to see what It could really do.

 

[Daviet]

Re: 1970 Johnson 9.5hp list of problems

1 & 3, Start with some basic checks, spark, should jump a 3/8" air gap and be bright blue. Compression, check both cylinders, I would think you should have somewhere around 70-90 lbs and be within 10% of each other.
2, normally the engine is propped to the boat size to get the proper RPM at wide open throttle. I would get the engine running properly first and then worry about the prop.
4, you are correct, the throttle plate should be closed at idle and the roller should contact the cam at the mark on the follower.
It sounds like you might need to do some carb work if the spark and compression are OK.
Check the spark and compression first, easy and cheap to do.

 

[Mr_Toogie]

Re: 1970 Johnson 9.5hp list of problems

Thank you for your response Daviet. Well, a little update to what been happening with in the last few days. I took the boat out and it started up fine like it always did. I played around with the trim a little and was able to get the boat up to 14 mph for the first time. After a few hours of stopping to fish then jumping to the next spot the motor began to become harder and harder to start. It also started to bog down and run rougher. by the end of the day and for the first time since I've gotten the motor i wasn't able to get it to start and i noticed that gas was coming out of the vent hole at the top of my float bowl. I figured my motor was flooding out. I got it home and took off the carburetor. I had plans to go fishing with a friend the next day, i was hoping i could do a quick carb cleaning and let the float dry out over night just to get it to work for one more day until i could do a full carburetor rebuild and complete going over. I know better... If you want it done right, then do it right, don't take short cuts. Anyways, I put the carb back together the next morning, got the boat out to the lake, got it started and it ran rough, smokey, with a strong gas smell. took it for a quick run and it was only running on one cylinder and i could smell the gas/oil mix pouring out somewhere. I open the hood to find i forgot to put the drain plug in the float bowl back in. So... I got to plug put back in and after that the motor flooded it's self out right away. It was a bad day all around with the trolling motor battery dying on me halfway across the lake form the landing, the tie down strap braking and not catching any fish. So the lesson i learned and the lesson i already knew was if your going to do something do it right the first time.

Anyways, Right now I've got the carburetor off and I've been giving it a very thorough cleaning. I'm waiting on a rebuild kit that should be here with in a few day. I've check the spark, the compression, pulled the fly wheel, check the points and everything there is good. it looks like who ever had the motor before me replaced the everything under the fly wheel, I replaced the spark plugs, all the hoses and wires are in great shape with no cracks, almost look new. That's as far as I've gotten at this point. really can't do much more until the kit gets to me. So again thanks for the reply and your information Daviet. I've put it to good use so for.

 

[Daviet]

Re: 1970 Johnson 9.5hp list of problems

Keep us informed on your progress, might help others with the same style engine.

 

[Mr_Toogie]

Re: 1970 Johnson 9.5hp list of problems

I finally got my rebuild kit, and finally got my motor put back together. Got it out to the lake and after finding out i didn't tighten my fuel pump cover... I tightened it up and it ran great. While i was waiting for the rebuild kit i did dig into the motor a little more to make sure i wasn't going to have any other issues. I cleaned up and re gapped the points, checked the impeller, and got some new spark plugs. The motor runs better then it's ever ran. even got it up to 14 mph (with the wind to my back) The only thing that came up the whole day was when i had it at low idle every once in a while it would... the best way i can explain it is the motor would "hiccup" and seem like it was going to cut out. All i had to do was give it a little throttle, it hesitated for a second, then it perked right back up. other then that it started every time with one pull, and at WOT it never missed a beat. Like i said before, if your going to do something, don't half *** it, do it right the first time. Now I need to find a new propeller and I'll be set.

So... Anyone have any idea's why the motor would "hiccup" like it does?
Also, any advice as to witch brand or type of replacement propeller I should get? I know it's an 8 1/8 X 8 propeller I have now and what I'm looking to get.


Thank you Daviet for you help and information, it really helped me out.

 

[Rick.]

Re: 1970 Johnson 9.5hp list of problems

Hiccup is a good description of what is referred to as a sneeze. Richen your slow speed needle about an eighth of a turn wait 30 seconds and see if it goes away. Keep repeating until it's gone. Glad to hear your liking you 9.5, I think they are neat old motors as well. Can't help with the prop. Mine still has the original plastic one in excellent shape. Best of luck. Rick.

 

[Haffiman]

Re: 1970 Johnson 9.5hp list of problems

If your ignition works, before starting carb jobs, check out the engine running temp and water circulation.
Impeller 5 years or more - change even if looking good.
Head gasket 10 years - change and check for clean passages in the block and head.
Thermostat: check in 'boiling' water for function and replace or install with new gasket.
Decarb the engine with Engine Tuner of Sea Foam. I prefer Engine Tuner as it is more effective to remove carbon build-up in the exhaust system as well.
With working ignition and working temp, you may start adjusting the carb.
As for propeller, it does not seem to be any other options available for your engine.