1973 65hp johnson Problem running in water

[norman2013]

Hey guys, I created a post earler and got some questions answered but I still have one problem with the motor. I checked the compression on all there cylinders, I checked all three spark plugs, and I cleaned the carbonate. When I run the motor with muffs in my driveway it runs just fine but when I take it to the lake it idels fine but once I go to put it in forward it dies. Any suggestion? Anything at this point will work great!

 

[boobie]

Re: 1973 65hp johnson Problem running in water

What was the compression ??

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

115
115
110

 

[boobie]

Re: 1973 65hp johnson Problem running in water

Do a cylinder drop test on it to make sure it's running on all 3 cylinders.

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

How do I do that?

 

[boobie]

Re: 1973 65hp johnson Problem running in water

Pull one spark plug wire at time when it's running and see if a cyl does not drop the rpm. That's the bad one.

 

[F_R]

Re: 1973 65hp johnson Problem running in water

Hey guys, I created a post earler and got some questions answered but I still have one problem with the motor. I checked the compression on all there cylinders, I checked all three spark plugs, and I cleaned the carbonate. When I run the motor with muffs in my driveway it runs just fine but when I take it to the lake it idels fine but once I go to put it in forward it dies. Any suggestion? Anything at this point will work great!

Perhaps it simply is idling too slow???? When you shift it into gear, it loads the engine and it stalls. Try increasing the idle speed setting. And of course there is the chance that you screwed up the link & sync when you worked on the carburetors. Finally, the spark advance (timer plate) may be sticking. If the carburetors open before spark advances, it will die.

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

Well I just got done doing the cylinder drop test and I think I have bad news…. I started the motor up just fine, went to the back and pulled the top boot off motor died. Then i replaced it and started it up again, removed the middle boot ran the same and then the bottom boot and ran the same. Once again pulled the top and it died on me…. So does this mean I have two bad cylinders? And if so how can I go about fixing it? Or is it pretty much trash now?

 

[boobie]

Re: 1973 65hp johnson Problem running in water

Will the spark jump a 7/16" open air gap on a spark tester ?? If it does, take the air box cover off and squirt some fuel into the bottom two cylinders and see if they pick up in rpm.

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

Take it off then put it back on? before starting?

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

Ok, I took the air box off and sprayed gas inside of the bottom two. The rpms went up for about 8 seconds then died back down. After doing it twice i did the drop test again and the same top cylinder was the only thing working.

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

At first i wasn't sure what a spark test was but after watching a few videos i see now. so no i havent done a spark test. Could this be why they are not firing bad spark plugs? or bad coils?

 

[boobie]

Re: 1973 65hp johnson Problem running in water

The bottom two cylinders are not getting fuel as you proved when you squirted fuel into them. Take the carbs off and clean them GOOD!!

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

Ok thanks for helping me! I will do that tomorrow afternoon and see if I have time to test it out! I will let you know my results! Thanks!

 

[boobie]

Re: 1973 65hp johnson Problem running in water

Be sure to check the high speed jets in the float bowls of the carbs for being clean.

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

Where is the high speed jets located?

 

[boobie]

Re: 1973 65hp johnson Problem running in water

Remove the plug in the float bowl and it's right back of it. Run a fine piece of wire through it to make sure it's clean. It takes a special screw driver to remove it.

 

[norman2013]

Re: 1973 65hp johnson Problem running in water

Update on the boat motor, I cleaned all carbs and gas lines and re assembled everything. Replaced the spark plugs and one turn of the key started right up. Immediately I could here that it was running better! Preformed another drop test and all three cylinders are working now. Went to sears and bought a craftsman compression check kit and checked the compression and were 130,130,131. Thank you for all of your help boobie! I couldn't have done it without your info!

 

[boobie]

Re: 1973 65hp johnson Problem running in water

You're more than welcome. Glad you got it fixed.