Rough idle after Seafoam

[waterboot]

I have a 1977 evinrude 75 HP outboard.

After I used the seafoam treatment 1 can in 3/4 gallon. I got a lot of grey goop coming out of the prop. After this it idles poorly.
If I have the engine idle in low rpm I can pull the middle plug of the spark plug and it stays running. If I pull the lower or upper plug then it stalls. If I increase the RPM (don't have a RPM meter) then the motor stalls if I pull the middle plug but seems to run the same if I pull the bottem or top plug?

Also motor doesn't seem to warm-up even after 15 minutes in idle I can pull the sparkplug and the are just warm to the touch. Can't find thermostat in manual I don't think it has one. Have it hooked up to mufs on water.

any help would be apriciated.

Thanks,

EK

 

[Vic.S]

Re: Rough idle after Seafoam

Not firing on middle plug! Have you cleaned and rest them?


Swap plugs around to see if fault moves with the plug If it does replace plug(s)


Part 37 is the thermostat, 101 is the pressure relief valve.

 

[tashasdaddy]

Re: Rough idle after Seafoam

did you read all the directions, replace spark plugs after decarb. this take a big toll on the plugs. water hose water is usually cooler, you have remove the crud that holds heat in the motor.

 

[waterboot]

Re: Rough idle after Seafoam

Not firing on middle plug! Have you cleaned and rest them?


Swap plugs around to see if fault moves with the plug If it does replace plug(s)


Part 37 is the thermostat, 101 is the pressure relief valve.

Thanks,

Replaced the spark plugs with new ones. -

 

[gcboat]

Re: Rough idle after Seafoam

And ------------------- what happened???????????????????

 

[waterboot]

Re: Rough idle after Seafoam

And ------------------- what happened???????????????????

Same, also moved plugs around.

 

[iwombat]

Re: Rough idle after Seafoam

Probably dislodged some crud from the fuel pump or the fuel lines and now it's sitting in the carb jets or passageways. It happens a lot if the motor has never been decarbed, or it's been a long time. You may need to dismantle and blow out your carbs.

If that's the case, it was going to happen sooner or later anyway. The decarb just made it happen in the driveway instead of on the water.

 

[waterboot]

Re: Rough idle after Seafoam

Probably dislodged some crud from the fuel pump or the fuel lines and now it's sitting in the carb jets or passageways. It happens a lot if the motor has never been decarbed, or it's been a long time. You may need to dismantle and blow out your carbs.

If that's the case, it was going to happen sooner or later anyway. The decarb just made it happen in the driveway instead of on the water.

Would I need a carb rebuilt kit. Or take apart and clean?

 

[iwombat]

Re: Rough idle after Seafoam

I'd think you might be able to get by with just a cleaning on this one. But a new kit never hurt anything.

Before you go there, do a full spark test and compression check though. Let's eliminate anything else.

 

[waterboot]

Re: Rough idle after Seafoam

I'd think you might be able to get by with just a cleaning on this one. But a new kit never hurt anything.

Before you go there, do a full spark test and compression check though. Let's eliminate anything else.

what do you mean with spark test? I did take the spark plugs out one by one and turned the ignition to make sure they spark and they did.

I don't have a compression meter do I need one?

Should I take the carbs off one by one?

 

[waterboot]

Re: Rough idle after Seafoam

Not firing on middle plug! Have you cleaned and rest them?


Swap plugs around to see if fault moves with the plug If it does replace plug(s)


Part 37 is the thermostat, 101 is the pressure relief valve.

Glad I looked nothing in there no thermostat no pressure relief valve. Run boat about 8 times before with no problems. Maybe other reason why previous buyer removed them?

 

[tashasdaddy]

Re: Rough idle after Seafoam

that's why it had so much carbon. it was not running at proper temperature. you can take the off together, but keep each separate. make the center carb, as it is different than top and bottom