70 evinrude idle in water problems

[Spabm12]

I just bought a 15' Manatee tri hull with a late 1970's 70 hp evinrude 2 stroke outboard. She runs fine on land (on a garden hose), no idle problems or anything once the engine is warmed up. I took the boat out for the first time today and found that the engine shuts off when put it in neutral when in the water. Forward and reverse both work fine and I was able to get the boat up to 32 mph gps at 5200 rpm. If I absolutely had to put the boat in neutral I used the warm up lever to rev the engine to about 2000 rpm so that the engine would not shut off (the battery is not very good and didn't want to risk it not being able to start again). Is it possible to solve the problem by adjusting the throttle so that it will idle in neutral at around 2000 rpm? What could be causing this problem? Any help is great appreciated. Thank you

 

[Daviet]

Re: 70 evinrude idle in water problems

What is your model number, does your carbs have a slow speed adjustment? What is your idle speed set at, 700-750 RPM in the water, in gear and warmed up?
If the spark and compression are good it might be time to overhaul the carbs.

 

[Spabm12]

Re: 70 evinrude idle in water problems

The model number is 70573 E. I don't know if the carbs have slow speed adjustment or not, I'm not sure what that is. I ran CRC engine tune up and decarbonizer through the carbs a few days ago. The spark plugs look good, haven't tested the compression but I would think it would be fine since it ran great in forward and reverse gears.