Cough coming out the Carb 120 hp Evinrude

R

rustyscrew

Petty Officer 2nd Class
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Mar 29, 2006
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I have a 120 hp Evinrude Outboard 1994. I fired it up to check on it before the fishing season. This thing always has run a little rough and especially coughs a lot on startup. I had the carb covers off and I noticed on at one point that exhaust or fuel spray came out of the carb during a cough. It only happened once in the 3 minutes I had it running.

Curious, is this indicative of a catastrophic failure about to happen?

thanks
 
H

Haffiman

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Re: Cough coming out the Carb 120 hp Evinrude

Is your 'quick start' working?
Double check the temp on each cylinder bank. it might just be a case of defective thermostat.
The 'cough' is caused by lean burning, the combustion goes down into the crank case. If it happens in the crank case (cylinder) powering the VRO pump, you run the risk of killing the air-pump membrane and valve.
Of course a compression test might give you some indication if anything more serious is on its way.
 
R

rustyscrew

Petty Officer 2nd Class
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Mar 29, 2006
Messages
141
Re: Cough coming out the Carb 120 hp Evinrude

Thank you. I will check the compression and hope that it doesn't do anything to the VRO which I think is already having trouble by leaking oil into the fuel line while it sits.
 
H

Haffiman

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Re: Cough coming out the Carb 120 hp Evinrude

'Leaking' oil into the fuel lines/pump/carbs when not used is normally caused by:
- Overpressure in the oil tank - faulty ventilation in the fill cap.
- The VRO tank is mounted ABOVE the engine and a siphon effect occurs.
 
metriccrescentwrench

metriccrescentwrench

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Oct 22, 2007
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2,598
Re: Cough coming out the Carb 120 hp Evinrude

If it's "lean sneezing" you can actually see a flash of flame in the carb throat when it sneezes (best viewed in low light such as at dusk).

If you're seeing fuel/air mixture spitting out the front of the carbs it could be bad reed valves, which will also make it run rough, especially at idle. If you hook up a timing light and point it at the front of the carbs (again in low light) it will help you see that.

If you determine that it is lean sneezing you'll want to take care of that since running lean can damage the engine. A good place to start would be a carb rebuild and cleaning.
 
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