Does this sound like a carburetor problem?

[alanfox55]

1993 Johnson 70 HP with fast and slow without VRO. Runs good on fast idle then at slow idle rpm goes up and down then drops down enough to stall.two videos how It was running and how it's running now. Cold engine start please excuse the warning horn not working properly.

 

[alanfox55]

Second video

 

[desertratz]

sounds like you are running on 2 cylinders intermittently. i would check spark on all 3 then check for fuel problems like plugged carb orifices.

 

[alanfox55]

Thanks I will do that

 

[oldboat1]

seems to idle at about 1000k. Put the l.u. in a large trash barrel -- fill with water and let it idle. Look for about 700 rpms with some back pressure. Pull off plug boots one by one and see if you get a change in rpms. No change means the cylinder isn't firing. It sounds pretty good to me, but easy to test for a dropped cylinder.

 

[alanfox55]

seems to idle at about 1000k. Put the l.u. in a large trash barrel -- fill with water and let it idle. Look for about 700 rpms with some back pressure. Pull off plug boots one by one and see if you get a change in rpms. No change means the cylinder isn't firing. It sounds pretty good to me, but easy to test for a dropped cylinder.

Thanks I bought a spark plug boot puller tool a while back to do just that. I did put new spark plugs in and that seemed to help. One of the old ones had to big a gap. They were all wet and black. I had it in the lake a couple weeks ago and it I ran in gear about 700 RPM. It would do the same thing idol fine then the RPM would drop down and it would stall. Once I advanced the throttle a little bit it was fine and it ran good at speed.

 

[Joe Reeves]

Check that the throttle butterflies are synchronized..... that all open and close at the same time. If just one butterfly is slightly open while the others are closed, weird surging problems will occur.

 

[flyingscott]

You need to idle in neutral around 1000 rpm with the lower unit submerged. About 800 in gear and warm.

 

[alanfox55]

Thank you Joe and Scott I will work on those things