Cleaned the carb and now won't start? '73 Johnson 9.5hp

[aamyot]

Hi Forum,
A while ago I ran down to the bottom of the tank and found plenty of old, bad gas down there.
My '73 Johnson 9.5hp has since been given a clean tank with fresh fuel and seafoam.
It got back into good shape, but would only start on 3-4 pulls, where it used to start with less than one full pull.
I ran it this way about 3 times a week for a couple months, but decided a carb cleaning was in order.

I pulled the carb and saw nothing of concern, but flushed it with carb cleaner anyway. All the passages and jets are totally clean, but once I installed it, I can't get it to start! Nothing changed other than flushing the carb.

Out of maybe 100 pulls, I got it to start twice, but ran low and rough and stalled out after maybe 30 sec. This was only after pulling the plugs and drying out the cylinders.

I have plenty of spark, the plugs are wet when removed, what the heck has happened?

Thanks,
Alex

 

[boobie]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

How did you check your spark ??

 

[aamyot]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

Just visibly with the plugs against the block. I have a spark tester that I should pull out, but was ruling out spark issue since the motor had started reliably right up until about an hour before I pulled the carb.

 

[Tim Frank]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

How did you clean the carb?

 

[aamyot]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

How did you clean the carb?

I used carb cleaner sprayed through all the passages.
I removed the float and jets and made sure they were all clear.

I also just put the gap tester on it and I have great spark across 3/8".
Check compression and both cylinders are at 50psi.

 

[boobie]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

Your compression sounds low. Borrow or rent another gauge and recheck. If it's still that low, you may have internal probs.

 

[aamyot]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

Your compression sounds low. Borrow or rent another gauge and recheck. If it's still that low, you may have internal probs.

I would normally agree with you, but since it ran well right before I cleaned the carb, I am pretty sure that the compression is at least adequate.

I haven't found a listing of spec compressions for motors. Its not in the repair manual that I have.
Anyone have a good source?

 

[aamyot]

Re: Cleaned the carb and now won't start? '73 Johnson 9.5hp

Problem Solved!
It was the carb float. I guess it got tweaked while I was cleaning it.
It was allowing no or very little fuel in. Kinda weird since the plugs were wet. I guess just not enough fuel.
It took me quite a lot of trial and error to fine tune it again.
I had no idea there was so little wiggle room in the bowl.
Anyway, its back to normal, starts on the first pull, I'm pretty happy.