Johnson 70 dies when advancing throttle

[Filmblanc]

Hi,

I have what I believe to be a 1983 Johnson 70. Idles great in neutral and in gear, but once I advance the throttle, it dies. Once I finesse it past the kill zone, the engine runs great.

Any ideas?

 

[Daviet]

Re: Johnson 70 dies when advancing throttle

Has the motor been sitting for awhile, did it just start running poorly?
Have you checked compression, spark and fuel delivery?
Could you post your model number so we know what we are working on.

 

[jtexas]

Re: Johnson 70 dies when advancing throttle

to determine the year, find the model number on the port side of the engine mounting bracket and cross-reference it here: http://www.shop.evinrude.com/media/document/ModelNumberReference.pdf

Fact that you can nurse it up to full RPMs implies a spark timing/carb syncronization issue. Refer to the picture below. Idle speed should be about 850-900 with the motor in gear in the water. If you're setting the idle speed on the muffs, make it about 1100-1200, then fine tune it after launching. RPMs will be lower when the motor's submerged.

The idle set screw should be neither all in or all out, but it has to be butted up against that throttle lever there. There's a black thumbwheel that adjusts cable length if needed.

Then observe the linkage as somebody advances the throttle...the cam should hit the roller right on that mark. Otherwise, the spark doesn't start advancing until its too late and she just falls flat on her face.

If that doesn't work, you'll have to rebuild the carbs.

Keep us posted.

 

[Filmblanc]

Re: Johnson 70 dies when advancing throttle

jtexas, your picture closely resembles my set up--very helpful.

Daviet, I just purchased the boat. It came with a mixture of old and new gas.

Thanks to both of you.

 

[Filmblanc]

Re: Johnson 70 dies when advancing throttle

jtexas,

Made the idle adjustment and she's running fine.

Thanks