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1968 Johnson 9.5 will not stay idle

J

Joshs

New member
Paid 20$ for the motor
Compression test 2x66 lb
Carb cleaned with forced air and carb cleaner
Fuel lines new all the way to the gas tank with new primer bulb
Cleaned the little fuel pump I believe is vacuum?
Fuel is non ethanol (90) mixed @50-1 or as close as possible

So I can get this motor to run, but for the life of me I can not get the motor to stay running.
It seems to want to run (rev up) when I close the choke. I'll make a 1/4 turn on the low speed needle, open choke wait a few seconds to see if it will idle. It chokes spirits sputters and dies. Over and over again.
I've started with the low speed needle from 1/4 turn out from seat and gone all the way to 3 full turns out. Do I keep turning? Is it still not getting enough fuel? Spark, compression?
I'll stop there. What is my next step guys!? Please help I want to get this Jon boat in the water!

Ohh and it does smoke like a bandit. But I've always been told they should be "Skeeter killers"
 
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Did you take the carburetor apart for cleaning , yes or no ?-----Does spark jump a gap of 5/16" on both leads on a test device, yes or no ?----Perhaps spark is jumping to ground from plug wires under the magneto plate.----A problem spot at a 90 degree bend there.-----Perhaps throttle plate is opening to early too.
 
racerone said:
Did you take the carburetor apart for cleaning , yes or no ?-----Does spark jump a gap of 5/16" on both leads on a test device, yes or no ?----Perhaps spark is jumping to ground from plug wires under the magneto plate.----A problem spot at a 90 degree bend there.-----Perhaps throttle plate is opening to early too.
Click to expand...



Yes Ive had the carb completely apart twice for cleaning. I wouldn't have any issues doing it again. It probably the easiest carb I've ever worked on. I took out the Jets and blasted with compressed air and carb cleaner both times.

As far as spark goes I only have the spark tester with the light. And tested them gapping from the head. What does this said gap tester cost?

If said test doesn't show me spark of 5/16 or better, where would you look first? The plugs? Or wires? Or something else?
 
You just have to do a proper test.-----Make something with wires ( even speaker wire ) glued to a piece of carboard or stapled to plywood.-----Have a 5/16" gap between the wires.-----Stick the end of one wire in the plug boot.----Ground the other wire on block.----The little fuel pump is operated by a positive pressure pulse.----Not so much by vacuum.----Compression is a bit low but that could be the gauge.
 
racerone said:
You just have to do a proper test.-----Make something with wires ( even speaker wire ) glued to a piece of carboard or stapled to plywood.-----Have a 5/16" gap between the wires.-----Stick the end of one wire in the plug boot.----Ground the other wire on block.----The little fuel pump is operated by a positive pressure pulse.----Not so much by vacuum.----Compression is a bit low but that could be the gauge.
Click to expand...

It gets spark it ran great for 2 days then out of nowhere started acting up
 
OH well------I have about 10 of the 9.5 HP motors for parts.-----Bring it over I think I can fix it without glancing at a manual.
 
I got about 10 of them around too. Great fishing motors. I think Racer is in Florida, or is that Joe? Wow 641 visits to his page. You serve coffee and donuts?
Good starting point for needle is about 2 turns I think, not sure. I work on so many carbs including GM Quadrajets. They are 3.5 turns to start.
 
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racerone said:
You just have to do a proper test.-----Make something with wires ( even speaker wire ) glued to a piece of carboard or stapled to plywood.-----Have a 5/16" gap between the wires.-----Stick the end of one wire in the plug boot.----Ground the other wire on block.----The little fuel pump is operated by a positive pressure pulse.----Not so much by vacuum.----Compression is a bit low but that could be the gauge.
Click to expand...

Ohh okay. I will do that next. In the event I'm on the + side of this test, what avenue do I take next?

And where do you suppose is a good start for the low speed jet? I'm getting 1/4 to 2 full turns out from seat for answers.
My first thought when it would rev up with choke closed was that it wants more gas.
 
Thanks Joe, gotta come see you sometime, you are on my wish list, remind me of my mentor here from years ago. So incredibly wise and talented.
Racer, too.....without you guys I just can't imagine how this forum would survive.......
Josh, run with choke most certainly means lean.....probably too lean to make it up with a low speed jet adjustmrnt alone.
 
Does the fuel primer bulb get hard when you pump it?
Does having someone constantly pumping the fuel primer bulb (acting as a manual fuel pump) make any difference?
 
My brother lives there. The whole family bailed out of Minnesota. The land of cold, mosquitoes, and taxes.
 
Did you remove the Core Plugs or Expansion plugs they're called which is item #39 and #42 on the carb diagram for the 1968 9.5 hp and clean behind them? They put new ones in the carb kits and sometimes people fail to remove them when they clean their carb. I might have been guilty of that one time and after I cleaned my carb a couple of times I finally removed the plug and got the trash that was behind it out. Motor ran great after that.
http://www.marineengine.com/parts/j...manufacturer=Johnson&section=Carburetor+Group
 
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Rook66 said:
Did you remove the Core Plugs or Expansion plugs they're called which is item #39 and #42 on the carb diagram for the 1968 9.5 hp and clean behind them? They put new ones in the carb kits and sometimes people fail to remove them when they clean their carb. I might have been guilty of that one time and after I cleaned my carb a couple of times I finally removed the plug and got the trash that was behind it out. Motor ran great after that.
http://www.marineengine.com/parts/j...manufacturer=Johnson&section=Carburetor+Group
Click to expand...

No I have no taken those off. But I haven't bought a carb kit via this carb and all its parts looked bran new. Is there a way I can remove and clean behind those and put them back or should I buy a carb kit? I did do the spark test. Passed no issues with either plug. I don't want to give up on this motor.. but it's now August and I haven't been on the water yet
 
timguy said:
Thanks Joe, gotta come see you sometime, you are on my wish list, remind me of my mentor here from years ago. So incredibly wise and talented.
Racer, too.....without you guys I just can't imagine how this forum would survive.......
Josh, run with choke most certainly means lean.....probably too lean to make it up with a low speed jet adjustmrnt alone.
Click to expand...

So what other way is there to provide more fuel to this motor besides the low speed adjustment?
 
The only way I've ever been able to remove them is by tapping a small punch in the center of them with a hammer to make a small hole or deep indention and then pry it out. Then of course you have replace it with a new one. In the link I provided in the post above item #42 is available for $5.67 plus shipping. As for me I would just buy a carb kit and replace all the old stuff including the float.

You have to be careful and not drive the punch all the way though the plug and damage something.
 
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There is a high speed jet ( orifice plug ) screwed into the bottom of the float bowl.----brass and about 5/8" long.----Did you find that item ?----Is that item confirmed clean and clear , yes or no.
 
I’m trying to get some info from this thread also. My 72 Johnson 9.5 will not run unless a continuously spray gas in the throttle body. Rebuilt the carb. New fuel pump. New plugs. Fresh gas. I’m lost at this point and need help
 
Just 2 things you must do.----Find and clean the high speed jet that is screwed way inside the float bowl.-----And remove the flywheel to inspect the coils.
 
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Are you sure it's getting fuel all the way into the float bowl? If so, then follow the lead of Racer and make sure the main jet is open. These are ultra simple carbs.
 
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