Topic: 1970 Johnson 9.5 nightmare. – Antique Outboard Motor Club,Inc

This topic has 13 replies, 8 voices, and was last updated 3 years ago by crosbyman.

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April 15, 2022 at 10:05 am #258312
russ
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This motor will not idle. New points.o20 gap.New coils wires and condensors.Carb has been cleaned and recleaned.Have synced cam and throttle on mark and a half inch on either side. Starts ok will run at higher throttle but still sneezes.Low speed adj started at 1 1/2 tried it in and back out no difference.Went 10 turns out still no difference when turning back in.Have plenty of spark both cylinders.Will start and run if wire is one cylinder or the other.Looked in reeds and looks like a couple of them are slightly open.Covered intake with one hand and turned motor over.They were blowing back on my hand and no sucking in. Could this be part of my problem. Russ
April 15, 2022 at 10:27 am #258315
frankr
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US MEMBER PAY BY CHECK
Not a very scientific test, but blowing back on your hand certainly sounds suspicious.
April 15, 2022 at 10:58 am #258319
crosbyman
Participant
Canada Member
to what extent did you clean and reclean the carb….did you remove the idle chamber cover plug and clean all orifices. these 9.5 9.5 carb must be 100% clean .

mine ildles all day long. did you try to raise the idle speed a bit by turning the side knob because you could be simply to low on the RPM setting of the throttle handle.

do the easy stuff first . there are 2 good videos part 1 & 2 on 9.5 carbs on utube.

(1500) 9.5 Hp Johnson Evinrude Outboard Carburetor Rebuild – 1of2 – YouTube

(1500) 9.5 Hp Johnson Evinrude Outboard Carburetor Rebuild – 2of2 – YouTube

Johnson (leeroysramblings.com)

“Quote”

On this carburetor, there is a 1/2″ core plug on the outer part of the carb that is inline with 3 small holes in the carb throat. These holes had to be drilled through the access hole this core plug covers up. However INSIDE and under the core plug is a plastic filler plug #0312909 that is not included. On the one I repaired, it would be impossible to remove this plastic plug without destroying it. Oh yes, this kit also included a old style fuel pump cover gasket and filter screen.

Instead of buying a new core plug (even if it is still available) I have used a icepick, drive it into the plug kind of sideways and pry It out. You can blow anything out of that cavity with compressed air and replace the plug by lightly peening the hole shut, reshape and replace it with the hole not totally filled with the metal, Then use a drop of JB Weld to reseal the hole/plug.

There could be many things to cause a poor or no idle situation, the high and low speed jets for this model must be absolutely clean. Good enough won’t cut it on this carburetor, it has to be SUPER CLEAN, and not just spraying it with carb cleaner.

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- This reply was modified 3 years ago by crosbyman.
- This reply was modified 3 years ago by crosbyman.
- This reply was modified 3 years ago by crosbyman.
- This reply was modified 3 years ago by crosbyman.
- This reply was modified 3 years ago by crosbyman.
April 15, 2022 at 11:03 am #258322
crosbyman
Participant
Canada Member
see pict on 9.5hp

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Monte NZ
April 15, 2022 at 11:54 am #258329
russ
Participant
Have removed the plugs on carb cleaned everything in the carb soaked it blew it out everything on carb that could come off did. New carb kit installed.Have linked and synced cam and throttle at every possible place to do so.Reed leafs looked to me that there were 3 that had a very small gap at bottom edge. Taped a piece of paper on one edge on intake turned motor over and paper lifted up. Put my hand over intake turned motor over could feel air blowing on my hand. Does not matter the rpm that I try to sync too it still does the same thing.
April 15, 2022 at 1:02 pm #258331
Mumbles
Participant
Excessive blow back like that indicates the reed petals are not closing properly and they may have some dirt lodged in them or one may be broken. Being a down draft style carb doesn’t help much keeping crud out either as the screen on top will let small stuff into the carb throat and reeds.

I’d suggest pulling the carb and the plate under it to gain access to the reed block. Once it’s in your hand, you should be able to inspect it more closely. Generally the reeds can be open no more than 0.010″ but I like to see them just closed as this seems to improve idle quality. A small amount of spit back is normal on most two stroke motors and can be expected.

As for the motor sneezing, that could be caused by worn crank seals allowing air to enter the crankcase and leaning out the mixture. Here’s how I check for leaky top seals.

https://youtube.com/shorts/cXt6fV6Z5rc?feature=share
April 15, 2022 at 1:52 pm #258336
russ
Participant
Did manage to see small bits of dirt when I got a better view with light. There were 3 that had a very small opening .Got them all cleaned out will try again tomorrow in setting cam and throttle. Thanks all…Russ…
April 16, 2022 at 5:55 am #258375
billw
Participant
US Member
Look really closely at the joint where the crank case attaches to the block. If need be, clean it with Simple Green, let it dry thoroughly and run the motor. Look for fuel and air spitting out from the joint, with a flash light and small mirror, as the engine is sneezing. If fuel leaks out, air can leak in, causing the sneeze. This is only after checking your reeds, of course.

Long live American manufacturing!
April 16, 2022 at 9:43 am #258382
fleetwin
Participant
US Member
The roller cam set up on these engines can be confusing. Be absolutely sure the carburetor is actually closing at low speeds.
April 16, 2022 at 1:34 pm #258389
russ
Participant
Yes it is closing all the way. Have my finger on the pin that goes thru the throttle shaft when I am turning the throttle.When it starts to move I can see in the carb at the throttle plate that is just starting to open.Thanks again all for your help. Will keep at it…….
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