1970 60hp Johnson

[Tourtney]

1970 60hp johnson. I’ve got a rough running engine at idle and at high idle (not pushing it because it is not out on the water). The rpms are surging up and down sometimes it will achieve a high rpm for a while before getting bogged down. At idle it seems like it shakes (more of a jerk) every once in a while. I tried adding a quarter can of Seafoam to the 1 gallon of gas mix but that seemed to make it worse. I know I have good 1/2 inch spark at the coil. At the plugs is is a bit less Than it probably should be around 3/8 inch but looks good color to me and steady when cranking on all three. Compression hasn’t been checked in a little while but it was good when checked all 3 around 120psi. Starts right up after turning off. I noticed a lot of white smoke when running today, I mean a lot. Checked temp with heat gun seemed even near each spark plug around 105 after 5 minutes off. I noticed white liquid in carb throats which upon a google search is actually water? It was hot and humid today but never noticed that after running before. My next step is to replace the gas with fresh gas because I know it’s been at least a year. it’s ethanol mix with oil. Just wanted you alls opinion on this thanks.

 

[F_R]

That cough/sneeze/jerk at idle is often called a "lean sneeze"---not enough fuel mixed with the air. Might be cured with a simple adjustment of the slow speed needle valves. If that doesn't work, you probably are going to have to go the next step,, which is checking out the whole fuel system.

 

[Tourtney]

Thanks I’ll give that a shot. I drained the tank and I found a white liquid in the Bottom. Could this be due to additives? The only thing I’ve added was Seafoam.

 

[oldboat1]

Clean tank, fresh gas, no additives. Start and warm up in the lake or in a barrel, water half way up the leg. Adjust air mix to dial out lean sneezing.

Standard advice is to get current compression readings, and current spark measurements with an open air adjustable tester.

 

[Tourtney]

Fresh gas, no additives. Adjusted carbs started at 1.5 turns not any better moved back to recommended setting of 3/4. Still “lean sneezing” at idle and high idle. I tried the sea foam “can and hose method” and ran through a gallon of it. I started noticing a light brown smoke after running it for 15 minutes and letting it heat soak for 15 minutes. I ran it after heat soaking it for 5 more minutes before switching to regular gas with no additives. It was still smoking brown but seems to be running a bit better. Continue the sea foam treatment? Smoke is mostly white about 90% with the brown smoke a little bit every once in a while.