1978 Johnson 6hp Runs great, Pain in the A$$ to start!!!

Average_azn

Seaman Apprentice
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Aug 17, 2014
Messages
34
Hi guys,
I've had my 1978 Johnson 6hp for about a year now. You guys helped me get it started last year. I used it almost every weekend last season, but
I'm fed up with how hard it is to cold start! Its so bad that i spend 10 mins cranking on it at home in a bucket to start it before any outing and let it run for 30 mins so that its hot when I hit the lake. I hear these motors are supposed to start first or second pull and I'm at the end of my wits with this motor.

Here's what I've done to it so far:
-Pulled flywheel, inspected woodruff key and mag packs - do they look okay to you? http://imgur.com/a/TFOv3#sJ1V97G
-Carb kit including new float
-New Plugs
is J4C a hot enough plug for this motor?
-New fuel pump
-Link and sync -
fairly certain I did this right, ill add pics of the alignment tonight.
-Low speed idle jet adjustment got it to the point where it runs very well at idle.

Symptoms:
-Hard to start
-Has trouble transitioning from low speed to high speed. Usually only when still cold, It sometimes dies if throttled up too quickly. You have to baby it to high speed immediately after starting it or it will start coughing and die. Once warm, it transitions normally.

Starting procedure:
1. Pump primer bulb until firm
2. Pull out choke knob
3. Quickly pull starting cord.
-At this point it usually starts for a half second and dies. Even if i quickly or slowly disengage the choke.
4. Push in choke completely
5. Yank on it 5000 times.
6. Thank the lord when it finally starts and stays running.

Anyone have any advice on what to try next. I'm willing to throw money at this motor if i can get it to start reliably. It cant get my boat on a plane but I dont care very much as I usually just put around the backs of the lake. I got so frustrated I bought a 1964 9.5hp Evinrude in rough shape on CL for $100. that motor starts every time now, but needs lots of work. It's also so old I would have trouble relying on it when on the water. Anyways that motor will have to wait for another thread.

Any ideas on next steps to get this motor to be reliable?
Thanks everyone!
 
Last edited:

bspeth

Senior Chief Petty Officer
Joined
Aug 30, 2013
Messages
758
Advance the throttle more on start up and see if that does it. I was not using enough at initial start but it starts first pull now.
 

Average_azn

Seaman Apprentice
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Aug 17, 2014
Messages
34
Thanks bspeth!
I usually start it with the cowling off and I advance it as much as I can before the plastic thing it slides on prevents it from starting. Sorry I have no idea what the terms are for these things. Basically it's as advanced as it can go and still allow me to pull the rope.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Make sure the carb throttle butterfly starts to open when the follower is aligned with the mark on the cam. And don't be afraid to choke it when cold. Other symptoms strongly suggest the high speed jet orifice may be dirty. It must be absolutely, positively, squeaky CLEAN without a trace of any varnish or contamination in it. Finally, it must be the correct one.
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,438
Compression test results are ?------Does spark jump a gap of 3/8" on this motor , yes or no.-----With the low speed needle set too lean it will idle very nicely but will stumble on acceleration.---So open that needle 1/8 turn at a time and see how it behaves.---You might have to disable / modify that feature on the recoil to prevent cranking.---------More throttle will definitely help in starting this motor.
 

Average_azn

Seaman Apprentice
Joined
Aug 17, 2014
Messages
34
Compression test results are ?------Does spark jump a gap of 3/8" on this motor , yes or no.-----With the low speed needle set too lean it will idle very nicely but will stumble on acceleration.---So open that needle 1/8 turn at a time and see how it behaves.---You might have to disable / modify that feature on the recoil to prevent cranking.---------More throttle will definitely help in starting this motor.

Compression was 75/75 psi. It jumped more than 1/2" on my spark tester both plugs. I never thought of disabling that "feature" i could give that a try tonight.
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
You've got the wrong plugs, for starters. Your motor has a CD ignition and should be running Champion L77JC4 plugs. Some books might show it as using an L78V, but I tend to avoid the surface gaps plugs as too cool.
 

Average_azn

Seaman Apprentice
Joined
Aug 17, 2014
Messages
34
You've got the wrong plugs, for starters. Your motor has a CD ignition and should be running Champion L77JC4 plugs. Some books might show it as using an L78V, but I tend to avoid the surface gaps plugs as too cool.


Are those the same as Champion 828M plugs? If so, ill pick some up on my way home!

Anyone know the best way to disable the starter stop without breaking it off?
 

Average_azn

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Aug 17, 2014
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Update! I picked up some new spark plugs on my way home. This time I made sure they were the right kind. Apparently autozone screwed me over when I brought in my last set of plugs to find a replacement. I have been running with RL86C plugs for the last year!

When I removed them they were both very fouled. Is this an indication of something? pics attached:

I removed the anti start "feature" as Racerone suggested. Now i went to start it with the new plugs and the throttle between start and fast position; choke fully out. It tried to start after a few pulls and then died. Although it ran longer tan it usually does with the choke out.

I dont fully understand what you are supposed to do when in starts with the choke out. Do you immediately push it back in? Is it supposed to keep running even when choked? Mine just quits after less than a second.


I pushed the choke in fully and this time it started in about 10 pulls. Better! but still not ideal when you're on a boat with no leverage. Even advancing the throttle to "fast" didnt help it start, It almost felt weird when pulling the rope in the fast position, like the flywheel wasnt moving with as much resistance. What else can i try?


Finally, it still has the low speed to high speed transition problem, can anyone tell from this video if the carburetor butterfly is properly synchronized? https://www.youtube.com/watch?v=va8jPveFrRE
 

pro-crastinator

Chief Petty Officer
Joined
Dec 12, 2013
Messages
453
Regarding choke "use" on cold start. (This is what I do, may be right and may be "wrong" but it is how I get through life)
Cold motor, pull choke, adjust throttle to "start" - pull starter rope - when motor stumbles to life, push choke in. I don't wait for anything to unchoke the engine.
That being said, I wont be pulling on the cord 14 times with no indication of life of the engine - without looking at something else like if the plugs are wet.
PS - your plugs did not look bad at all.

WHere are you located in GA?
Good luck.
 

bspeth

Senior Chief Petty Officer
Joined
Aug 30, 2013
Messages
758
Set the throttle to 1/4.Choke it and pull it.When it starts and then dies quickly,push in the choke and it should start on the next pull with no choke. I think you may need to have another look at the carb. Still learning this, I am no expert.
 

Average_azn

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Joined
Aug 17, 2014
Messages
34
Thanks everyone! The new (Correct) spark plugs seem to make it dramatically easier to Start. Now it starts within one to two pulls once i got the low speed jet dialed in. I think the carb needs to be looked at again to get over the low to high hiccup, but I'm happy with it for now.

Thanks for your help guys!
 
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