1970 6hp johnson starts only at high throttle

[hardwater fisherman]

I bought a 1972 25hp last fall and the 6hp was a throw in..... I think the 6hp is probably the better of the 2....The motor had new coils points and condensers when I bought it..... I have put a carb kit and impeller as well as a new thermostat... I have got it to idle super slow in neutral and both gears running in a barrel..... It takes throttle and back down to idle nicely without flinching... The only problem is it needs to be on the the high part of the cam to start..... There is a mark on the cam and it will idle when the follower is on that mark... I am putting it on a boat Friday for the first time to see how it does... I think it is going to run well but it really revs while starting.... I can pull for ever until I throttle up and it catches right away.. It does not seem right to me but maybe it is normal?

 

[oldboat1]

Sounds like you've got it dialed in well. I've got a 9.9 that is perfect when warmed up, but needs the idle mix dialed a little richer for cold starting -- then back to the leaner setting after warm up. (Talking maybe 1/4 turn.)

 

[hardwater fisherman]

Yes it started better after I turned the needle out a little... But I will probably need to lean it up some.....No throttle stop or kill switch so I just need to find the starting and stopping points.....

 

[hardwater fisherman]

The first run went very well... It was a little hard to start at first and died a couple of times at idle... So I seated the slow speed needle and backed it out 1 1/2 turns... Still hard to start and died at idle.... I then turned the needle out a little and I never had to touch it again....Trolled for several hours and in and out of gear at very low speed and I never touched the throttle... But it is still hard to start.... I need to use the choke once and then it starts the second or third time... But only at a high throttle setting. If not choked it does not start within the first five or six pulls. And then if chocked it needs two more pulls... The motor once dialed in never missed a beat while trolling or at WOT.... I can idle it down super slow and put it in forward and reverse with touching the throttle.... I am just not sure what can be done about the starting issue? What can cause the motor to need a little choke even when warm? But at the same time no running issues...

 

[oldboat1]

Think you found the right base setting for the motor. Maybe you still need to go a tad richer for cold starting (with choke and high idle), then dial it back when warmed up.

 

[hardwater fisherman]

That makes sense but it does not matter if cold or if it is warmed up... The starting is the same.. On my other motors I am used to using choke in the morning and then not needed for the rest of the day... At least the fishing was good we got a 33"musky and 4 walleye between 17"and 23"...

 

[oldboat1]

Nice fish!

Nothing else comes to mind on the starting issue, unfortunately.

 

[Tim Frank]

Did you remove the Welch plugs and clean behind them?
Verify that the correct HS orifice is installed. Lots of off-the-page mods done by previous owners.
Make sure that the LS needle end is per spec and not broken or misshapen from over-tightening.

 

[hardwater fisherman]

Thanks...The water levels in the rivers and lakes are very low this year.... And the fish are 'trapped' in sections of the river, and not too hard to find.... There is one thing I never really thought about until this morning.... I forgot to mention that the starter spring is a little weak... And now I am thinking that I may not be getting a good cranking speed.. Someone in the past replaced the rope and when I bought it the rope did not retract all the way.... I installed a new rope and rewound the spring following a manual.... The spring still did not take all the rope... I took the starter apart this morning and I found the outer spring is distorted on the bottom 8 to 10 coils.... When i wound the spring I turned it CCW as said in the manual..... It appears that someone in the past has wound the spring the wrong way....Or the rope broke and damaged the spring..... The springs are not at all cheap.... Has anyone tried to reshape these springs?....... I do not know if this is causing the hard start problems..... But while pulling the rope by the time the pinion engages the flywheel more the half the travel of the rope is gone.....If I need to replace the spring I will be looking for a complete motor with a good starter.....

 

[hardwater fisherman]

Did you remove the Welch plugs and clean behind them?
Verify that the correct HS orifice is installed. Lots of off-the-page mods done by previous owners.
Make sure that the LS needle end is per spec and not broken or misshapen from over-tightening.

Yes the carb was rebuilt by me including the welch plugs and high speed speed jet removed.... The needle appears to be in good shape as well...

 

[Tim Frank]

Verify that the correct HS orifice is installed. Lots of off-the-page mods done by previous owners.

Yes the carb was rebuilt by me including the welch plugs and high speed speed jet removed.... The needle appears to be in good shape as well...

The question was "Did you verify that the HS jet was the correct one?"
When you buy a used outboard, all bets are off on OEM configuration.
What is the model number?

 

[hardwater fisherman]

Sorry no model number I am going by paint color and decals.... I do not think the high speed jet was ever changed... Someone had started by changing coils points and condensers... The carb was not touched and the last person to own said it would not start.....When I pumped the fuel bulb it went rock hard right away... I tried to start it with no luck.... I sprayed a little fuel in the throat of the carb and it started..... When I pulled the carb apart the float was rotten and throughout the carb.... The little clip that holds that lifts the float needle was rusted and crumbled, and the needle was stuck in its seat... I could not see light through any hole in the carb.... After soaking a little I could remove the high speed jet... And now just looking at the diagram there is only one high speed jet for these carbs.... I do not think the carb has ever been off until I took it off.....It does look like someone tried to get the nuts off because the one side behind the starter was rounded a little....Do you think it would idle really well ...Take throttle well and run at WOT if the high speed jet was somehow not right? Last Saturday morning it trolled up and down the river for several hours without once missing a beat...And returning and ran Wot for 20 mins.. and then back to idle no problem...

 

[hardwater fisherman]

This is not my motor but mine looks just like it.... So if I had to guess on the model number then 6R70B.....